Symposium 1: ERP and MEG studies on phoneme discrimination,
and semantic and syntactic processing: Basic and clinical research
Symposium 2: Delayed cardiovascular recovery: A possible alternative to reactivity models of disease
Symposium 3: The psychophysiology of emotion: The role of stimulus relevance, motivational congruence, and coping potential
Panel Discussion 1: Entering the domain of the dense electrode array: Conceptual and methdological problems
Symposium 4: Ambulatory psychophysiological assessment: Methodological challenges and clinical opportunities
Symposium 5: Psychophysiology in the clinic: The anxiety disorders
Symposium 6: Ten years after: Paul Obrist's legacy to cardiovascular psychophysiology
Symposium 7: ERPs to subliminal stimuli: Markers for unconscious processes
Panel Discussion 2: Review and funding of psychophysiological research: Perspectives, opportunities, and strategies
Symposium 8: Psychophysiological studies of biobehavioral mediators of risk for alcohol abuse
Symposium 9: Synthetic Emotion
Symposium 10: Steady-state evoked potentials: New methodological approaches and applications
Symposium 11: The role of cortisol in memory, attention, and emotion
Special Panel Discussion: Psychophysiology: The Shape of its Future
ERP and MEG studies on phoneme discrimination, and semantic and
syntactic processing: Basic and clinical research
Chairs: John F. Connolly & Kimmo Alho
Participants: Kimmo Alho, John Connolly, Myong Yoon, Ryan D'Arcy
The intent of this symposium is to present new findings of ERP and MEG studies in language comprehension in basic research contexts and in clinical applications. The goal is to present studies that move along the continuum of complexity of processing beginning with basic pre-attentive processing of speech components, moving to phonological and semantic processing of simple sentences, then to neural mechanisms involved in the processing of compound sentences that have semantic and/or syntactic violations in the first and/or second sentence segment, and finishing with a presentation of the clinical applications of this basic research. The first presentation deals with ERP/MEG findings demonstrating MMN responses to phonemes that reflect pre-attentive processes that are lateralized to the left hemisphere. The second talk will briefly review the phonological mismatch negativity (PMN) and present recent findings demonstrating its temporal sensitivity to the "uniqueness point" and work conducted in Helsinki (Connolly, Alho et al., in preparation) demonstrating its lateralization to the left temporal cortex. The third presentation reports recent findings using compound sentences to study the manner in which semantic and syntactic processes interact in the comprehension of text and the importance of sentence context on these effects. The final paper describes recent advances in the application of knowledge derived from the basic research exemplified in the first three papers to the investigation of clinical syndromes characterized by language dysfunction or to the assessment of intellectual functioning in non-communicative individuals.
Mismatch negativity reveals hemispheric lateralization of preattentive
speech processing: Recent electrical and magnetic recordings
University of Helsinki
The mismatch negativity (MMN) is an event-related brain potential (ERP) elicited by deviant sounds occurring in a sequence of repeating sounds. Recent studies from our research unit indicate hemispheric lateralization in processing of unattended speech sounds reflected by MMN and its magnetoencephalographic (MEG) counterpart (MMNm). Naatanen et al. (Nature, 1997, 385, 432-434) found that MMNm is generated with a larger amplitude in the left than in the right auditory cortex by deviant vowels when they are prototypical phonemes of the subject's native language. Tervaniemi et al. (in preparation) observed a stronger MMNm in the right than in the left auditory cortex to a change in a musical chord whereas the opposite was true for a vowel change. Alho et al. (in preparation) found a left-hemisphere dominant MMNm also for changes in a consonant- vowel syllable. Moreover, source activity modelled by Rinne et al. (in preparation) for electrical MMNs to changes in eight types of sounds ranging from sinusoidal to phonetic indicated a left-hemisphere dominance for MMNs in the phonetic end of the stimulus continuum and a right-hemisphere dominance in the other end of the continuum. While positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) have shown a left-hemisphere dominance for attentive processing of speech sounds, the aforementioned MMN studies indicate hemispheric lateralization already at the pre-attentive level of speech processing.
Sensitivity of the phonological mismatch negativity to phonemic violations
and its lateralization to the left temporal cortex: ERP and MEG findings.
John F. Connolly
The phonological mismatch negativity (PMN) is an event-related potential component that has been shown in several studies (e.g., Connolly & Phillips, J. Cognitive Neuroscience, 1994, 6, 256-266; Connolly et al., J. Clinical & Experimental Neuropsychology, 1995, 17, 548-565) to be sensitive to the initial phoneme of a word that ends a spoken sentence incongruously or congruously but unexpectedly. The PMN has been temporally and functionally separated from the N400 and has been shown to be specific to the auditory modality (Connolly et al., Electroencephalography & Clinical Neurophysiology, 1995, 94, 276-287). More recently, the additivity of these two components was evaluated (Kutas & Hillyard, Biological Psychology, 1980, 11, 99-116); results suggested the two components are additive and lend further support to the independence of the PMN and N400. Also, recent work is described that manipulated the point at which sentence-ending words became contextually incongruous; unexpected/incorrect phonemes occurring at word onset (The piano was out of leaves.), at word midpoint (The gambler had a bad streak of luggage.) or at a late position in the word (He mailed the letter without a stampede.). This manipulation in point of phoneme deviance resulted in a progressive delay in the occurrence of these components (Connolly & Randhawa, in preparation). Finally, recent work conducted with colleagues in Helsinki (Connolly, Alho et al., in preparation) using both electrical (ERP) and magnetoencephalographic (MEG) techniques has replicated the electrical results from earlier work and localized the PMN to the left temporal cortex. In sum, these findings support both ERP and MEG techniques in the identification of the functional components of speech comprehension as well as their neuroanatomical localization.
Distinctive neural responses to semantic anomaly and/or inflectional
number-disagreement in compound sentences: An ERP study
Myong G. Yoon & John F. Connolly
We studied neural responses to semantic anomaly and/or inflectional number disagreement in compound sentences during reading by normal subjects.  The ERPs of semantically anomalous (but inflectionally correct) verbs in the final clauses of the compound sentences showed negative shifts (N400) between 350 and 600 ms (peak; 450 ms) with respect to those for appropriate correct verbs. When the semantically anomalous verbs appeared in the first clauses, their ERPs showed the negative shifts (N400) about 100 ms earlier between 250 and 450 ms (peak; 350 ms).  The ERPs of inflectionally incorrect (but semantically appropriate) verbs in the first clauses showed positive shifts (peak; 600 ms: P600) with respect to those for correct verbs.  The ERPs of semantically anomalous and inflectionally incorrect verbs were either P600 type or N400 type, depending on the locations of recording electrodes.  The ERPs of semantically anomalous and inflectionally incorrect verbs showed large positive shifts (P600) compared with the ERPs of semantically congruous and inflectionally incorrect verbs. This result reveals that neural responses to the inflectional disagreement are greatly enhanced by the semantic anomaly of the verbs.  The ERPs of the object words (located at the ends of sentences) of semantically anomalous verbs showed very large negative shifts during a period between 300 and 750 ms. These results reveal the prominent influences of various sentential contexts on the human brain's neural responses to linguistic stimuli.
The application of event-related potentials (ERPs) in the assessment
of receptive language functions
Ryan C.N. D'Arcy, John F. Connolly, Joseph M. Byrne, & Christopher A. Dywan
Dalhousie University & Izaak Walton Killam Hospital
While there is a long and distinguished history of basic research with event-related potentials (ERPs), more concentration on the clinical applications of this technique is paramount. Language is well suited for investigations of an applied nature because various ERP components associated with linguistic processing have been identified. Further, receptive language dysfunction is frequently noted in aphasic individuals suffering from stroke, but due to communicative limitations, may not be assessable with traditional psychometric measures. Accordingly, we have explored the feasibility of adapting standardized neuropsychological measures of language for computer presentation with ERPs. These investigations have demonstrated that components related to speech perception and recognition memory (e.g., N400 and P300) can be elicited by standardized test stimuli and thus utilized to evaluate language independent of behavior. Specifically, studies of vocabulary and comprehension have demonstrated that: 1) test items within an individual's ability, but not beyond, can be differentiated on the basis of their neural responses; 2) subtle increases in difficulty do not influence behavioral responses, but reliably attenuate neural responses; and 3) these results exist at the individual level, thus maintaining clinical applicability. The potential implications of this novel technique will be elucidated and some recent experimental findings with the Token Test (De Renzi & Vignolo, 1962, Brain, 85, 665-678) and the Psycholinguistic Assessment of Language Processing in Aphasia (Kay et al., 1992) will be presented. The objective of this work concerns the development of an electrophysiological aphasia battery and the extension of this approach into other realms of cognition (e.g., memory/amnesia).
Delayed cardiovascular recovery: A possible alternative to reactivity
models of disease
Chair: William Gerin
Participants: David Sheffield, Laura Glynn, Julian Thayer, Paul Mills
Discussant: Nicholas Christenfeld
Cardiovascular reactivity remains the predominant psychophysiological model of stress effects on cardiovascular disease. However, several studies now suggest that cardiovascular recovery of pre-stress resting levels may provide important prognostic information, independent of that provided by reactivity-testing. As with reactivity, it is important to understand the determinants of delayed recovery at several levels, as well as to examine the effects of delayed recovery prospectively. This panel covers a broad range of issues related to recovery. Paul Mills describes the role of adrenergic receptors in regulating blood pressure recovery, and Julian Thayer reports on a model of anger inhibition and cardiovascular recovery that may shed light on mechanisms underlying blood pressure regulation, with a focus on vagal influences. Both authors report on Black-White differences which may help us to understand the greater prevalence of hypertension in Black Americans, as well as the role of individual differences in anger expression (Thayer) that may contribute to delayed recovery. Laura Glynn describes the role of situational factors, specifically distraction, that may prolong blood pressure elevations in response to stress; and David Sheffield reports on a prospective study in which cardiovascular recovery accounted for a greater proportion of variance than did reactivity in blood pressure 5 years later, thus providing validation for the clinical importance of measuring recovery. Nicko Christenfeld will discuss the papers, with reference to methodological and measurement issues, and will provide an integration of the issues raised by the presenters.
Does blood pressure recovery from an active mental stressor predict future
blood pressure? A comparison with blood pressure reactivity
David Sheffield1, George Davey Smith2, Douglas Carroll3, Martin J. Shipley4, & Michael G. Marmot4
1University of North Carolina, 2University of Bristol, 3University of Birmingham, 4University College London
The evidence linking the magnitude of cardiovascular reactions to stress and future blood pressure status is mixed. Few studies, though, have examined recovery in this context. We report on a prospective study which allows us to compare the contributions of reactivity and recovery to the prediction of future blood pressure. A sample of 969 British male public servants (average age 44.0 years), revealed as normotensive at an initial screening of blood pressure, had their blood pressure monitored in the laboratory at rest, while undertaking an active mental stress task, Raven's matrices, and after the task. Blood pressure reactivity was calculated as laboratory task-rest difference; recovery was defined as level post-task. Follow-up blood pressure screening was conducted, on average, five years later. Analysis was by step-wise multiple regression, with age always entered first. In the case of follow-up systolic blood pressure, a model including age, initial screening blood pressure and resting laboratory blood pressure accounted for 42 per cent of the variance in follow-up screening blood pressure, and, while systolic blood pressure reactions entered the equation, they accounted for less than one per cent of the variance; recovery did not enter the equation. In the case of follow-up diastolic pressure, age and diastolic blood pressure at initial screening accounted for 35 per cent of the variance. In this case, though, diastolic blood pressure recovery entered the equation, accounting for an additional three per cent of the variance. These analyses suggest that recovery may have greater prognostic significance than reactivity.
Emotion, rumination and the rate of blood pressure recovery from stress
Laura Glynn1, Nicholas Christenfeld1, & William Gerin2
1University of California-San Diego, 2Cornell University Medical Center-The New York Hospital
While many emotional stressors are themselves brief--being cut off on the freeway, or insulted by a stranger--their effects can be long-lived. One factor which may influence this duration is rumination. To examine this issue, we conducted two experiments on BP recovery from laboratory stressors. In the first experiment, we hypothesized that emotional stresssors may lend themselves more readily to rumination than non-emotional, physical stressors, and so produce slower cardiovascular recovery. Seventy-two subjects experienced one of four stressors. Blood pressure was continuously monitored during baseline, stress, and recovery periods. The reactivity produced by the emotional tasks (mental arithmetic with harassment and shock threat) was the same as that produced by the physical tasks (walking in place and cold pressor). However, at the end of the ten minute recovery period, the physical task subjects were within 5 mmHg SBP of baseline, but the emotional task subjects were still elevated 15 mmHg. In the second experiment, we manipulated rumination directly. All subjects experienced mental arithmetic with harassment. Half were given a distractor task (a questionnaire) designed to prevent rumination, and half were simply left alone. Those with the distraction were within 5 mmHg two minutes after the stressor, while those left to ruminate were, ten minutes later, still 15 mmHg above baseline. These data suggest that rumination can play a major role in recovery to baseline levels. If CVR is involved in later CVD, it seems likely that the effect of stressors can be magnified considerably by processes such as rumination.
Anger expression, ethnicity, and cardiovascular recovery
Nancy Dorr1, Julian F. Thayer1, & Jos F. Brosschot2
1University of Missouri-Columbia, 2University of Amsterdam
Recently, Brosschot and Thayer (1997) proposed a model of anger inhibition and cardiovascular recovery that suggested that differences in socially accepted forms of anger expression may help to account for the large black-white difference in hypertension. Specifically, previous research has shown that socially dominant individuals recovered more quickly from an anger instigation when they had the opportunity to respond with expressions of anger. Conversely, socially non-dominant individuals recovered more quickly when they responded with anger inhibition. We tested this model in the context of responses to racist and non-racist provocation in a group of college undergraduates. Forty-six male participants (23 white, 23 black) engaged in two debates with a confederate. One debate had a racist theme and one debate had a non-racist theme. In both cases, the participant was provoked by the confederate. Systolic and diastolic blood pressures were recorded during the debate and during a recovery period which followed each debate. Anger expression was manipulated by having half of the participants rate the confederate (anger expression) and half of the participants rate their best friend (anger inhibition) preceding the recovery period. Results indicated that white participants recovered more quickly when they had an opportunity to express their anger whereas blacks recovery more quickly when they inhibited their anger, (SBP: F(1,37) = 4.66, p<.05; DBP: F(1,37)= 4.96, p<.05). These results are consistent with the notion that socially acceptable forms of anger expression may contribute to individual differences in cardiovascular recovery. Underlying mechanisms including the role of the vagus in BP regulation will be discussed.
Adrenergic mechanisms underlying blood pressure (BP) reactivity and recovery
Paul J. Mills, Michael G. Ziegler, & Joel E. Dimsdale
University of California-San Diego
Adrenergic physiology plays an important role in regulating cardiovascular responses to and recovery from stress. Data from two separate studies are presented examining these phenomena. In the first study, interindividual variations in adrenergic receptors and agonists were examined for their association with BP responses to an acute laboratory stressor. In the second study, BP recovery and adrenergic receptors were examined following a 2-3 day stay at a Clinical Research Center. Hospitalization routinely results in a lowering (recovery) of chronically high BP and this study examined potential adrenergic mechanisms underlying this phenomenon. In study 1, 50 hypertensive and normotensive Black and White individuals had their beta- and alpha-adrenergic receptor sensitivity determined through agonist infusions. Norepinephrine, epinephrine, BP and heart rate responses to a standardized mental arithmetic task were then obtained. Distinct subgroups of individuals were identified, with BP and heart rate responses determined by the sensitivity of adrenergic receptors and the accompanying catecholamine responses. Relatively insensitive receptors generated sizeable end-organ responses in the presence of high catecholamine concentrations and, conversely, more sensitive receptors generated sizeable end-organ responses in the presence of more moderate catecholamine responses. In study 2, 88 Black and 77 White hypertensive and normotensive individuals were studied following a 2-3 day hospitalization. Blacks (especially Black hypertensives), as compared to Whites, showed a smaller decline in both systolic (p<0.01) and diastolic (p=0.05) BP following hospitalization. Black hypertensives also showed increased beta-adrenergic receptor sensitivity (p=0.02). Together, the combined data provide evidence for an adrenergic role in acute BP responsivity and recovery.
The psychophysiology of emotion: The role of stimulus relevance,
motivational congruence, and coping potential
Chairs: Arvid Kappas & Craig A. Smith
Participants: Craig A. Smith, Joe Tomaka, Rex Wright, Arvid Kappas
Discussant: Gregory J. McHugo
Recently, interest in affective processes has burgeoned, stimulated by findings concerning the influence of positive and negative mood states on the startle reflex. Yet, some feel that reducing affect to a single valence dimension is too reductionistic because distinct emotional states of the same valence clearly differ with regard to expressive and subjective responses, and, according to numerous hypotheses, physiological activity. In the years since SPR featured a panel discussion on "theoretical issues in the psychophysiology of emotion" (1988) theoretical developments have been made, many in the context of appraisal theories of emotion. These theories postulate that physiological responses are a function of the importance and the motivational congruence of a stimulus for an individual as well as his/her perceived coping potential, and that these responses are organized around the implications of these appraisals for adaptive action. This perspective accords well with notions advanced by others, such as Obrist and Brehm. Because, it holds physiological activity in emotion to be a function of the individual's evaluation of the affective stimulus, this approach may be particularly useful in interpreting "troublesome" observations regarding physiological differentiation of emotions, such as an apparent lack of stimulus specificity or large individual differences in responding. The symposium presents different theoretical and empirical approaches that consider the role of stimulus relevance, motivational congruence, and coping potential on physiological responses in an attempt to go beyond positive and negative mood states as discriminators of emotion, and to begin to delineate the organization of physiological activity in emotion.
Appraisal as an organizing principle
Craig A. Smith
An important proposition that has emerged from appraisal theory is that the physiological activity associated with various emotions is organized around the adaptational implications of the appraisals that give rise to the emotions. On this view, emotions function to motivate individuals to respond to adaptationally relevant circumstances that have been identified through appraisal, and the physiological activity in emotion serves to support physically these coping responses. Although these general ideas have been proposed for at least thirty years (e.g., Lazarus, 1968, Nebraska Symposium on Motivation, 175-266), it is only within the past decade that the specific implications of these propositions have begun to be developed and empirically tested (e.g., Smith, 1989, Journal of Personality and Social Psychology, 339-353). Even today, progress in testing this approach is slow, perhaps because the theory and its implications for physiological activity in emotion are not widely known.In this presentation, I first consider the fundamental assumptions and principles of appraisal theory, as well as the theoretical reasons for expecting emotion-related physiological activity to be linked to appraisal. Then, the derivation of specific, testable hypotheses from the more general theoretical principles is considered, and the nature of such hypotheses is contrasted with a more traditional categorical approach of testing for general emotion-specific patterns of physiological activity. Finally, the promise of the appraisal approach to understanding the organization of physiological activity in emotion is illustrated with recent findings that explicitly link appraisal information to the dynamics of spontaneous autonomic activity (e.g., finger temperature, skin conductance) during ongoing problem-solving tasks.
Relation of threat and challenge to emotion and coping theory
Joe Tomaka, Julie A. Penley, & Rebecca Palacios
University of Texas at El Paso
Threat and challenge are distinct patterns of stress-related responding that result from cognitive appraisals of situational demands considered in relation to appraisals of ability to cope with such demands (see Tomaka, Blascovich, Kelsey, & Leitten, 1993, Journal of Personality and Social Psychology, 248-260). In addition, we have demonstrated that threat and challenge have distinct affective, behavioral, and cardiovascular consequences. For example, threat appraisals result in negative affect, poor task performance, and a pattern of cardiovascular response that includes moderately increased cardiac output coupled with an increase in systemic vascular resistance. Challenge appraisals, in contrast, result in less negative affect, better task performance, and a pattern of cardiovascular response that includes increased cardiac output, coupled with a decline in systemic vascular resistance. Research has shown threat and challenge response patterns can be produced experimentally and that such patterns are reliably related to aspects of personality.In this presentation we briefly discuss the nature of threat and challenge responses and then turn to more recent research examining the motivational underpinnings of such responses and research relating threat and challenge to the broader context of emotion theory. We conclude with suggestions for applying threat and challenge research to other areas of psychophysiological inquiry. Throughout this presentation, we emphasize the advantage of using patterns of autonomic responses over single parameter investigations and emphasize the use of multiple converging measures--including physiological and nonphysiological--to identify psychophysiological constructs.
Perceived performance capacity and cardiovascular response to a fixed
Rex A. Wright
University of Alabama at Birmingham
An analysis is presented that suggests that effort and associated cardiovascular (CV) responses to a fixed (specific) behavioral challenge are determined jointly by the difficulty of the challenge and the performer's appraised ability in the relevant performance realm. As difficulty increases, effort and CV responsivity should first be greater for low ability - than high ability individuals, then be greater for high ability- than low ability individuals, then low and equivalent for both groups. The exact points at which the perceived-ability/CV-response relation reverses and then disappears should depend on the importance of success. Where success importance is relatively low, the changes should occur at relatively low difficulty levels; where success importance is relatively high, the changes should occur at relatively high difficulty levels. The analysis is supported by data from a variety of recent experiments, and would seem to have implications for a number psychophysiological phenomena, including sex and race differences in CV response.
His master's voice: Acoustic analysis of spontaneous vocalizations in
an ongoing active coping task
There is still little evidence supporting the hypothesized relationship between expressive behavior and outcomes of cognitive evaluations along appraisal dimensions. For example, Scherer (1986, Psychological Bulletin, 143-165) hypothesized that goal obstruction is accompanied by an increase in the higher frequency spectrum of the voice, in the fundamental frequency (F0), as well as in period-to-period perturbations of F0 and amplitude (jitter and shimmer). However, these relations have not yet been tested systematically. One of the difficulties in studying such hypotheses is to find a paradigm that is well suited to assessing facial and vocal activity in an ongoing active coping task. I have developed a video-game paradigm to test the impact of manipulating goal congruence and coping potential on facial and vocal activity. Specifically, participants controlled a Pacman-type video game using a limited set of voice commands "gauche", "droite", "haut", "bas", while multiple physiological measures were taken (SC activity, IBI, finger temperature, facial EMG at the Corrugator Supercilii site). Recording highly standardized vocalizations permits averaging within words, accounting for the variance in acoustic changes that are due to their phonetic structure. Because the voice commands were the direct mode of interacting with the game, I consider these vocalizations as spontaneous and adequate for the test of the hypothetical relations between appraisals and acoustical changes. Specifically, I will present data relating appraisals of goal congruence and coping potential to event-related physiological activity including vocal changes, ANS responses, and EMG activity at the Corrugator Supercilii site. The advantages and disadvantages of using acoustic analyses of spontaneous vocalizations to study affective processes will be discussed.
Entering the domain of the dense electrode array: Conceptual
and methdological problems
Chair: Emanuel Donchin
Participants: Emanuel Donchin, Don M. Tucker, Kevin M. Spencer, Thomas R. Elbert
Discussant: Greg McCarthy
An increasing number of laboratories are beginning to use "dense electrode arrays" for recording EEG. Such arrays cover the scalp with 64 or, more recently, with 128 electrodes. These recording arrays are used because they are likely to allow a detailed examination of the componential structure of the ERPs. The dense arrays can also be used to support numerical methods for source localization such as BESA. The realization of these possibilities requires, however, that we solve the serious problems presented by the massive data base that is acquired when such arrays are recorded. The participants in this panel will review the special challenges presented by the dense arrays. Some of the pitfalls encountered when working with dense arrays will be reviewed, and guidelines for avoiding these pitfalls will be discussed.
The challenges presented by dense electrode arrays
University of Illinois at Urbana-Champaign
This presentation will introduce the panel. I will review the history of the use of multiple electrodes in ERP research, the problems that arose when scalp distribution became a defining attribute of ERP components, and the solutions that have been adopted by different investigators. The manner in which these issues are transformed when one uses 128 electrodes will be examined and the special issues that arise in this context will be reviewed. In particular I will review critically attempts to adopt to the mapping of ERPs methods that derive from fMRI research. The visual inspection of selected maps, or of movies, will also receive a critical examination. It will be my contention that, as is true for data obtained with a single electrode, there is no substitute for a detailed quantitative analysis of the data obtained with dense arrays. Criteria for evaluating approaches to the quantification of brain maps will be proposed.
Spatial Nyquist of the human EEG
Don M. Tucker, Ramesh Srinivasan, & Michael Murias
University of Oregon and Electrical Geodesics, Inc.
Measuring brain electrical activity at the scalp surface requires adequate sampling of the electrical fields in their spatial as well as temporal extent. Temporal sampling (A/D conversion) is defined by the Nyquist theorem: The sampling rate must be more than twice the highest frequency of the signal. To be accurate, spatial sampling must also follow the Nyquist theorem, with an electrode density that is more than twice the spatial period (frequency) of the brain's electrical fields. In simulation studies with a 4-sphere model (estimating the conductivities of brain, CSF, skull, and scalp), we represented field patterns with differing spatial frequencies by sets of spherical harmonics. These studies showed that the highest spatial period that can be resolved with a 32-channel montage (distributed across the surface of an average-sized head) is 14 cm, defining a topographic feature of 7 cm, about the size of a lobe of the brain. If there is greater spatial detail than this in the scalp EEG, it cannot be measured by a 32-channel recording, and it will be aliased into the lower spatial frequencies. In empirical studies with 128-channel EEG recordings, we sub-sampled visual ERPs, motor ERPs, and various EEG phenomena to examine the adequacy of 64-, 32-, and 19-channel montages. These data showed substantial detail in individual subjects' scalp topographies that was often distorted in interpolations from 64-channel subsamples, and that was severely aliased by 32- and 19-channel montages.
Temporal-spatial analysis of the late positive components of the ERP
Kevin Spencer, Joseph Dien, & Emanuel Donchin
University of Illinois at Urbana-Champaign
Several late positive components of the event-related brain potential (ERP) have been reported as responses to deviant stimuli: the P300, Slow Wave, P3a, and novelty P3. The relationships between these components were investigated using a high-density electrode array for EEG recording. Temporal and spatial principal components analyses (PCAs) were used to reduce the dimensionality of the data (15 subjects X 129 electrodes X 252 timepoints X 9 stimuli), and to estimate component activity.15 subjects were studied in 4 experimental conditions. In two "passive" conditions, subjects solved a word puzzle or read a book while being presented with an irrelevant auditory oddball series. In two "active" conditions, subjects responded to rare target stimuli in two auditory oddball series containing rare and frequent stimuli, or rare, frequent, and "novel" rare stimuli.Temporal PCA produced temporal factors for the Slow Wave and for the other three late positive components combined. The spatial patterns of the P300, P3a, and novelty P3 were then dissociated by spatial PCA, which produced two main spatial factors with anterior and posterior topographies that differed in their relative contributions to the components. We conclude that the novel stimuli elicit both a P300 component and a primarily frontal "novelty P3" component. Our data suggest that the "P3a" and the "novelty P3" are distinct ERP components.
Mapping EEG-potentials: A strategy for uncovering cortical sources
Markus Junghoefer, Thomas Elbert, & Brigitte Rockstroh
University of Konstanz
For any given distribution of the electrical potential on the surface of the head, there exists an infinite number of possible source configurations. This law presents a major problem when determining source locations. A second theorem, however, maintains that the potential distribution on any closed surface that encloses all the generators can be determined uniquely from the surface potential map. Therefore, the blurring of the electrical potential distribution which is caused by the high conductivity of the skull can in principle be compensated. An alternative to this "cortical mapping" which also compensates the spatial low pass that is characteristic of the transformation between cortex and scalp is current source density (CSD) calculation.In this presentation, we describe a uniform method for calculating the interpolation of scalp EEG potential distribution, the CSD, the potential distribution on the surface of the brain, and its CSD. It will be shown that interpolation and deblurring methods such as CSD or cortical mapping are not independent of the inverse. Not only the resolution but also the accuracy of these techniques, especially those of deblurring, depend greatly on the spatial sampling rate (i.e., the number of electrodes). Using examples from simulated and real (64 and 128 channels) data it can be shown that the application of more than 100 EEG channels is necessary to guarantee a reasonable accuracy in the calculations of CSD or cortical mapping. Likewise, it can be shown that using more than 250 electrodes does not improve the resolution.
Ambulatory psychophysiological assessment: Methodological challenges
and clinical opportunities
Chairs: Thomas W. Kamarck & Kevin T. Larkin
Participants: Thomas W. Kamarck, Jochen Fahrenberg, David Sheps, Kevin T. Larkin
Discussant: Derek Johnston
Research over the past decade suggests that ambulatory assessment may provide independent information about psychophysiological functioning not available from laboratory data alone. Ambulatory monitoring studies present a number of methodological challenges; challenges which are increasingly surmountable with the advent of recent technological and methodological advances. At the same time, these studies provide important opportunities for enhancing our understanding of clinical disorders such as hypertension and cardiovascular disease. The presentations will focus on recent developments in ambulatory psychophysiological assessment, highlighting both the challenges and the opportunities associated with these methods. Dr. Kamarck will present findings from his research employing a computerized strategy for simultaneously gathering diary ratings of emotional activation and cardiovascular measures. In Dr. Fahrenberg's presentation, empirical evidence outlining the use of accelerometry devices for measuring posture and movement during ambulatory monitoring periods will be discussed. Using coronary artery disease patients, Dr. Sheps will present findings using ambulatory monitoring of cardiovascular ischemia to examine how depressive mood is related to ischemic events occurring during daily living. The correspondence between clinic and ambulatory measures of blood pressure in defining essential hypertension will be presented by Dr. Larkin. Finally, Dr. Johnston will serve as discussant and integrate major findings from the papers presented with a focus upon suggestions for future empirical work.
The effects of psychosocial influences on ambulatory blood pressure:
Contrasting different measurement and data analytic strategies
Thomas W. Kamarck, Saul S. Shiffman, Leslie Smithline, Hayley Thompson, Jeff Goodie, Jean Paty, Mary Ann Gnys, & Jon Kassel
University of Pittsburgh
Measures of ambulatory blood pressure (ABP) may provide independent markers of cardiovascular risk; previous reports show that psychosocial factors (mood, work stress, and social support), in turn, may exert important influences on ABP. Previous studies have used a variety of approaches to measure these influences. Here we examine the consequences of different strategies for assessing ABP determinants, using data from a sample of healthy community adults. 120 subjects (54 % female, 50 % African American) were assessed at 45 minute intervals for 6 days using an automated ABP device and a palmtop computer for recording concurrent behavioral states, yielding an average of 109 observations for each participant. Our data suggest that: (a) individual differences in average negative affect and arousal (between-subject assessments) are not associated with ABP differences, whereas fluctuations in emotional activation (within-subject assessments) show substantial associations with cardiovascular activity in the natural environment, (b) a number of time-varying covariates (e.g., activity, posture) alter but do not eliminate the effects of emotional activation on ABP, and c) there are significant individual differences in the effects of emotional activation on ambulatory cardiovascular activity. These differences were associated, in a subsample, with laboratory measures of cardiovascular reactivity taken on the same individuals. These data demonstrate the importance of considering temporal, situational, and person factors in assessing the psychosocial determinants of ABP, and they illustrate some of the merits of a computerized approach for ambulatory diary assessment.
Posture, motions and tremor: Detection by calibrated accelerometry, DC-/AC-splitting,
and joint time-frequency analysis
Jochen Fahrenberg, Friedrich Foerster, Manfred Smeja, & Wolfgang Mueller
University of Freiburg
Assessment of posture and motion is an essential issue in ambulatory monitoring since physiological responses, for example changes in heart rate or blood pressure, may be due to changes in physical activity and posture. Continuous recordings (24-hour) of posture and motion can be generally useful in behavior assessment. Calibrated piezoresistive accelerometer devices were employed in these investigations. The slow motion (DC-) component allows for assessment of change in position referring to the gravitational axis; the AC-component represents acceleration along the sensitive axis of the device. Recordings were made in 24 subjects for nine conditions: sitting, standing, lying supine, sitting and talking, sitting and typing on a PC keyboard, walking, climbing stairs, walking down stairs, and cycling (all repeated once). The recordings were continued outside the laboratory. A participant observer recorded duration and type of activity of subjects. The Vitaport2 recorder/analyzer system (Vitaport EDV Systeme GmbH) was used (placement of sensors: sternum, dorsum of lower arm segment, frontal aspect of thigh and lower leg, respectively). The findings indicated that the classification of posture and motion based upon the accelerometer recordings was highly reliable. The agreement between behavior observation and kinematic analysis was satisfactory, although discrepancies existed in some subjects. This methodology was also employed to assess tremor activity in 22 patients with Parkinson's Disease during laboratory tasks and 24-hour monitoring using joint time-frequency analysis. A short account on findings regarding frequency and amplitude of tremor, and distribution of tremor episodes across 24 hour recordings will be presented.
Depressed mood is related to heart rate variability and ischemia during
David S. Sheps & David Sheffield
University of North Carolina at Chapel Hill
Depression and depressed mood have been associated with subsequent morbidity and mortality in patients with coronary artery disease (CAD). One explanation for these findings is that patients with depressed mood might display exaggerated sympathetic activity resulting in more myocardial ischemia during daily life. To examine this possibility, 81 patients with documented CAD (61 men, 20 women; mean age = 61.5 years) underwent 24-48 hour ambulatory ECG monitoring during normal daily activities. Depressed mood was assessed by the depression scale of the Minnesota Multiphasic Personality Inventory. An ischemic episode was defined as at least 1 mm horizontal or downsloping ST segment depression at 0.08 seconds after the J-point that lasted at least 1 minute. Depressed mood was related to the number of ischemic episodes/24 hours (r=.23, p<.05) and modestly related to the total duration of ischemic episodes/24 hours (r=.19, p<.10). These relationships remained largely unaltered after adjustment for disease severity (number of occluded vessels) and medications. Heart rate variability was determined in a subsample of 35 patients. Depressed mood was related to average heart rate (r=.52, p<.01) and inversely related to SDNN (r=-.53, p<.01). Again, adjusting for disease severity or medications did not alter the strength of these relationships. Finally, average heart rate was modestly related to the number (r=.34, p<.10) and duration (r=.32, p<.10) of ischemic episodes/24 hours; SDNN was unrelated. These analyses suggest that depressed mood may be related to increased sympathetic tone and more myocardial ischemia during daily life and may account for the observed relationship between depression and mortality.
The "white coat" effect: False positives and false negatives
in the assessment and diagnosis of essential hypertension
Kevin T. Larkin, Scott L. Schauss, & D. Michael Elnicki
West Virginia University
Blood pressure (BP) determinations in the clinic often bear little resemblance to BP measured through ambulatory or home monitoring. Although a great deal of attention has been paid to 'white coat' hypertensive (WCH) patients (persons who have high BPs in the clinic but normal arterial pressures at home or work), little is known about patients whose BP is within normal limits in the clinic, but whose average daily arterial pressures fall within the hypertensive range, i.e., 'white coat' normotensives (WCN). The purpose of this study was to investigate the frequency of both false positive (WCH) and false negative (WCN) determinations of hypertensive status using clinic BPs with ambulatory BPs as a reference. Sixty-six community volunteers were recruited to participate in a BP assessment study. Auscultatory BPs were obtained in the clinic, home BPs were measured over a one-week period, and ambulatory BPs were obtained over a 24-hour period. Although clinic, home, and ambulatory measures of BP were all highly correlated, categorization using JNC V blood pressure guidelines was inconsistent. Nine volunteers were categorized as WCH and 12 were categorized as WCN using mean clinic and ambulatory BPs. WCN patients were more mentally active and slept less than WCH patients, and were more physically active than normotensive volunteers during ambulatory monitoring. Similar findings were observed with analysis of home BPs. This study demonstrated that establishing a diagnosis of hypertension based solely upon clinic BP measures results in a significant number of both false positive and false negative diagnoses using ambulatory or home BPs as standard referents.
Psychophysiology in the clinic: The anxiety disorders
Chairs: Walton T. Roth & Steven H. Woodward
Participants: Bruce N. Cuthbert, Alex L. Gerlach, Frank H. Wilhelm, Steven H. Woodward
Discussant: Walton T. Roth
Because of the prominence of both episodic and chronic hyperarousal symptoms in the anxiety disorders, these disorders have been a focus of clinically oriented psychophysiology for many years. Since all animals have fear systems, infrahuman neurophysiological research into fear has pushed deep into the brain; probably more is known about fear's biological substrates than about the substrates of any other domain of psychopathology. One would expect, therefore, that clinical application of psychophysiology to the anxiety disorders would be particularly highly developed and could be considered an important test case for the clinical utility of psychophysiology in general.Participants will present research findings demonstrating the contributions as well as limitations of psychophysiological methods as applied to the diagnosis, management, and theoretical understanding of anxiety disorders such as simple phobia, social phobia, agoraphobia, panic, and PTSD. Methods described will include fear-potentiated startle, ambulatory cardiac, respiratory, and electrodermal recording, facial blood volumetry for measuring blushing, and trauma-cue induced responsivity assessed via multiple indices.We intend to address these questions: What does psychophysiology have to offer the anxiety disorders clinic, and what can it not yet provide? Where are clear avenues for progress, and where are questions still ill-formed? What will be the role of ambulatory psychophysiology? What are the limits of animal models of human fear in explicating clinical anxiety?
Specific phobia and other anxiety disorders
Bruce Cuthbert, Evelyn Sullivan, Cyd Strauss, Margaret Bradley, & Peter Lang
University of Florida
The clinical studies to be described are theoretically driven by basic research on emotion, reflecting animal experiments involving states of appetitive and defensive motivation. This work has defined a subcortical fear circuit, including the sensory thalamus, amygdala, and periaqueductal central gray. Research has shown that the startle reflex and autonomic reactivity are augmented in fearful animals, and that these responses depend on an intact fear circuit. Work with non-clinical human samples in our laboratory has demonstrated a corresponding startle potentiation, in fear conditioning, fear imagery, and while subjects attend to unpleasant pictures or sounds. In exploring anxiety disorders psychopathology, these results are paralleled most closely by patients with specific phobias. Clinically, these patients most closely resemble non-anxiety populations, e.g., they show lower scores on measures of general psychopathology and depression. Specific phobic patients respond with a pattern that suggests a tightly organized, and reliably elicited, fear memory structure. They show larger autonomic responses to imagery of their own phobic material than other anxiety disorders groups. Further, their reactions are reliably predicted by such factors as trait and state imagery vividness, and general distress; such relationships are much reduced for patients with social phobia and panic disorder. Specific phobics also show marked fear-potentiated startle to phobia-relevant stimuli (whether imagery or pictures), again exceeding comparable responses of other patients. Thus, specific phobia best exemplifies activity in the fear circuits elaborated by animal models, and represents a standard against which to evaluate fear-related responding in other patient groups.
Subtypes of social phobia
Alexander L. Gerlach1, Frank H. Wilhelm2, & Walton T. Roth3
1Stanford University, 2Philipps-University Marburg, 3PAVAHCS
In recent years social phobia has attracted a substantial amount of research. Considerable effort has been made to discriminate various subtypes of this disorder. The hope is to isolate subcategories and ultimately to develop specifically tailored treatments. Unfortunately either the discrimination of these subtypes has turned out to be unreliable or it has been unclear whether differences are qualitative or simply quantitative. The most common distinction, that between generalized vs. non-generalized social phobics, has usually been shown to be quantitative. Generalized social phobics score higher on standard social phobia questionnaires, report more anxiety during behavioral tests, and are rated as more severely impaired by clinicians. However, a few studies have found that compared to generalized social phobics, discrete social phobics have higher heart rate reactivity during performance situations but lower reported anxiety, a dissociation that suggests a qualitative difference. We will present data that failed to confirm this finding: In our sample of 30 social phobics heart rate was higher in generalized than specific social phobics in two of three social tasks. A neglected physiological measure of social phobia is superficial facial blood volume. Blushing is a common complaint of social phobics, distinguishing them from agoraphobics, for example. We will document a larger increase in facial blood volume in an embarrassing situation for social phobics than controls. However, we will also show that social phobics in our sample who were especially concerned about blushing did not exhibit greater changes in facial blood volume than social phobics not concerned about blushing.
Multi-channel physiological assessment of a simple phobia in the natural
Frank H. Wilhelm1 & Walton T. Roth2
1Harvard University, 2Stanford University
We evaluated the feasibility of recording multiple physiological anxiety indices outside the laboratory, testing specific anxiety theories in 14 flight phobics and 15 controls. Benefits of baseline adjustment and transformation for all variables, and adjustment of heart rate (HR) by ventilation to give "additional HR" were calculated using individual relations between ventilation and HR during an exercise test. Additional HR was not different between phobics and controls when leaving the hospital, but it was significantly greater for phobics when entering the airplane, accurately reflecting their increased subjective anxiety while physically active. In contrast, HR did not differ between groups on either occasion. A comparison of effect sizes of 13 physiological parameters during flight showed that additional HR was the best anxiety index even when subjects were seated. Although respiratory rate and minute volume, indicators of hyperventilation, did not distinguish groups, phobics paused more during inspiration than controls. Phobics also showed more skin conductance fluctuations and less respiratory sinus arrhythmia, pointing to enhanced sympathetic and reduced cardiac parasympathetic activation in phobics during flight. Skin conductance level was related to reported sweating. Accuracy of diagnostic classification was higher for the single best self-report measure, SUDS anxiety, than for additional HR (90% vs. 79%). We conclude that ambulatory monitoring of multiple physiological systems in phobic situations can yield objective information about certain symptom categories, but does not necessarily sharpen diagnostic categorization.
Psychophysiological assessment of PTSD
Steven H. Woodward
The induction of sympathetic arousal by reminders of trauma has been proposed to be a key diagnostic criterion for PTSD, perhaps even the "gold standard" against which other diagnostic methods should be validated. Published reports have relied principally upon heart rate acceleration to index sympathetic arousal, and to a lesser extent upon skin conductance. "False negatives", i.e., patients who meet DSM-III/IV criteria for PTSD but who fail to exhibit substantial heart rate accelerations when exposed to trauma reminders are frequently observed. False negatives reached a level of approximately 30% in a recently completed DVA Cooperative Study of over 1000 Vietnam combat veterans. While some consumers of this research may conclude that most false negatives over-reported their PTSD symptoms on interview, such conclusions are premature in light of our continuing ignorance about the nature of long-term adaptation to trauma andthe methodological limitations of current studies. Indices of arousal and arousal regulation which have yet to be measured in studies of trauma-cue reactivity include heart rate variability, T-wave amplitude, blink rate, pulse transit time, and startle probe amplitude. Only one study has examined EEG. We will present data comparing Vietnam combat veterans who were trauma cue "responders" versus "non-responders" as defined by heart rate accelerations. These groups exhibited significant differences in their levels of high frequency heart rate variability for baseline periods during which they were exposed to positively-valenced stimuli. This finding in itself suggests that the powerful downregulatory influences on the heart must be considered when assessing trauma cue reactivity by heart rate. Further group comparisons and individual case reports will be presented to illustrate the complex interpretive challenge facing those who try to diagnose PTSD psychophysiologically.
Ten years after: Paul Obrist's legacy to cardiovascular psychophysiology
Chair: Paul Grossman
Participants: Jasper Brener, James E. Lawler, Alan W. Langer, Kathleen C. Light, James A. McCubbin
Paul Obrist died ten years ago, yet his language is still heard in the words and voices of cardiovascular psychophysiologists the world over. His concepts remain beacons and warnings to psychophysiology and behavioral medicine as these disciplines enter the twenty-first century. In the wild and woolly 1960's and 70's, Paul Obrist, almost single-handedly, transformed cardiovascular psychophysiology from a side-show of psychology where simple cardiac measures were primarily employed as putative markers of covert psychological processes. Obrist's vision of psychophysiology was to expand the reaches of cardiovascular physiology to behavioral and psychological domains that had been previously neglected by academic physiologists and physicians. This meant not only describing the unique hemodynamic responses evoked by discrete mental tasks and emotional states, but also addressing the mechanisms and biological function of varying circulatory adjustments to behavior. To achieve these ends, Obrist embarked upon an ambitious, systematic series of human and animal investigations, pioneered the use of pharmacological agents in psychophysiological investigation, and developed an intriguing set of hypotheses linking the genesis of essential hypertension to stress-related cardiovascular reactivity and systemic overperfusion. These are merely a few of his accomplishments. Among his many personal attributes, Paul was keen, down to earth, straight talking, and unafraid of a good argument. He displayed an uncommon sense of passion and was a loyal friend and mentor. In this symposium, five of Obrist's closest colleagues and former students will present their views of the legacy he left us.
Obrist's view of the behavioral-cardiovascular interaction
State University of New York at Stony Brook
This presentation will describe experiments by me and my students that were inspired by Obrist's ideas regarding behaviorally related variations in cardiovascular performance. The concept of "overperfusion" is central to Obrist's theory about the genesis of essential hypertension. Normally cardiac output is precisely scaled to the perfusion requirements of the tissues. However, sympathetically mediated increases in myocardial performance augment blood flow to levels that exceed metabolic demand. This overperfusion is counteracted by homeostatic mechanisms including vasoconstriction that restore normal rates of blood flow. However, both the elevated cardiac output and the subsequent increase in peripheral resistance cause blood pressure to rise and are potentially pathogenic. These ideas of Obrist stimulated us to investigate sources of variation in heart rate (as an index of cardiac output) observed in behavioral situations. Experiments on the relationship between heart rate, striate muscle activity and oxygen consumption were conducted with Wendell Goesling, Ethel Eissenberg, Susan Middaugh, Keith Phillips, Sam Connally Andy Sherwood and Jennifer Moses. These studies indicated that most behaviorally related variations in heart rate could be accounted for by metabolic demand that, in turn, could be attributed to striate muscular activity. However, under certain conditions, heart rate was elevated above metabolic demand. According to Obrist, these suprametabolic elevations in cardiac activity were also triggered by incipient motor processes - preparation for action. This notion has been examined experimentally by Sherwood, Moncur and me, and theoretically by Requin, Ring and myself. More recently, Obrist's ideas have stimulated experiments by Roy and Sequeira-Martino that identify brain sites of striate muscular-visceral interaction in cats.
The borderline hypertensive rat (BHR) as an animal model for studying
the mechanisms of environmentally induced hypertension
James E. Lawler & Ingrid P. Edgemon
University of Tennessee
While psychophysiologists are familiar with the contributions of Paul Obrist's research with human subjects, they are less familiar with his contributions utilizing animal subjects. His early work with dogs will be briefly reviewed. It is this work that led to his interest in assessments of aspects of cardiovascular function in humans other than heart rate. The dog work was thus an early tool for his emphasis on becoming more biological in all psychophysiological research. That orientation has had a profound impact on my own career, and that impact will be briefly reviewed. The development of the borderline hypertensive rat (BHR) will be discussed. The BHR is the first generation cross of inbred rats with genetic hypertension and those with no positive family history of hypertension. The BHR, but not the normotensive rat, shows chronic elevations in blood pressure when subjected to shock-shock conflict stress. These elevations persist even in the absence of continued stress. Second, a high salt diet also produces a chronic elevation of blood pressure. Third, an exercise program can prevent stress-induced hypertension in this model. Once the model was developed, research was then directed at elucidating the mechanisms involved. The basic orientation is that there are central/renal interactions involved in producing permanent hypertension in the BHR. Recent studies addressing the role of these mechanisms will be reviewed. These data show a critical role for the renal nerves, especially during the developmental phase of hypertension. CNS changes also show patterned alterations in the BHR which are absent in the WKY, when using either compound stressors (salt and stress) or salt intake alone. Finally, the BHR appears to be an ideal model for studying the role of family history in altering cardiovascular reactivity to stress following chronic interventions such as exercise or high salt intake.
The legacy of the cardiac-somatic hypothesis: This one's for you, Paul
Alan W. Langer & Mark R. Larson
Introduced by Paul Obrist in 1968, the cardiac-somatic hypothesis continues to exert a remarkable influence on cardiovascular psychophysiological research. Initially advanced to elucidate biological processes when seeking to establish what Paul called "biological yardsticks of psychological states," this simple but elegant formulation went on to frame just about every significant problem addressed by cardiovascular psychophysiology. The most significant application of the cardiac-somatic hypothesis continues to be the problem of cardiovascular reactivity. The role of the sympathetic nervous system in mediating cardiac reactivity to behavioral stress has been repeatedly shown to occasion a dissociation of cardiac and somatic processes, the best examples of which are additional HR and overperfusion (elevation in cardiac output in excess of metabolic demand). Perhaps the most vexing problem for Paul was the relationship between overperfusion and blood pressure control and its potential role in the development of essential hypertension. Paul speculated that overperfusion might be relevant to conditions such as borderline hypertension, but this was refuted by several earlier studies suggesting that the elevation in cardiac output, at rest in borderline hypertensives, was linked to an appropriate increase in metabolic demand (oxygen consumption). Unfortunately, Paul never got around to systematically examining this himself. Nevertheless, we would now like to present new data which shows that persons with mildly elevated blood pressures not only exhibit overperfusion during a baseline preceding exercise but that this effect is potentiated during the baseline prior to an active coping stressor. The legacy of the cardiac-somatic hypothesis continues. This one's for you, Paul.
The reactivity hypothesis: Building on an uneven foundation
Kathleen C. Light
University of North Carolina at Chapel Hill
Paul Obrist was a spokesman for the potential importance of high cardiovascular (CV) reactivity to stress in the pathogenesis of CV disease. Some have suggested that little additional predictive information is obtained beyond that provided by traditional risk factors. Also, there is a need for refinement of the reactivity hypothesis itself. It has been shown that increased exposure to life stress, operationalized as job strain, lack of social support, etc., increases the risk of adverse CV outcomes. Thus, a high reactor should not demonstrate the same subsequent BP if s/he spends the next 20 years in a low stress vs. high stress context. The tests for the reactivity hypothesis should examine outcomes as a function of both the independent (additive) and interactive effects of high CV reactivity with measures of exposure to life stress. In a recent 10-year follow-up of 103 male college students initially tested by Obrist et al, current clinic SBP was best predicted by a model in which SBP during a reaction time task plus current score on the Daily Stress Inventory plus their interactions added to a base model of traditional risk factors (model R2 = 28% vs. base model R2 = 15%). Among 58 of these men who also completed 24-h ambulatory monitoring at follow-up, DBP at work alone was best predicted by DBP during the cold pressor, plus current job supervisor support, plus their interaction, added to body mass index (BMI) (model R2 = 31%), while DBP at home with others was best predicted by DBP during the reaction time task plus total social support plus their interaction, added to BMI (model R2 = 24%).
A neo-Obristian view of the contributions of Paul A. Obrist
James A. McCubbin
University of Kentucky
The late Paul A. Obrist was a man who infused into his work both a romantic passion and a lunchbucket-style work ethic. Obristian psychophysiology, as the forerunner of mechanistic behavioral medicine, relied heavily on methodological development as well as conceptual clarity. Paul spent years developing his measures, from indices of left ventricular function to his automated blood pressure contraptions that anticipated much of today's remarkable tools. He advocated multiple converging methodologies. For example, to verify the accuracy of his blood pressure devices he used direct radial artery cannulae. He assessed the sensitivity of these devices using amyl nitrite and other heroic manipulations to produce reliable blood pressure changes. Therefore, his research was grounded in an empirical foundation that maximized the impact of his findings. Paul also pioneered practical approaches to semi-quantitative assessment of autonomic tone in the intact behaving human. The creative use of pharmacological receptor blocking drugs during behavioral manipulations allowed Paul to implement a degree of biological specificity heretofore unknown in our field. Finally, his appreciation of the predictive utility of individual reactivity differences in the disease process has probably stimulated more research than any other single contribution. While Paul may not have been the first to embrace these varied methodological and conceptual issues, he parlayed them into a research juggernaut that pushed the field into a new era. Paul bore heavily the birth trauma of these times. However, the Neo-Obristian conceptus flourished through the next decade and continues to stimulate exciting new research.
ERPs to subliminal stimuli: Markers for unconscious processes
Chair: Howard Shevrin
Participants: Howard Shevrin, Scott Bunce, Edward Bernat, Philip Wong
Discussant: Marcel Kinsbourne
As cognitive psychologists have begun to agree that unconscious processes exist, it becomes of increasing interest to ask if ERPs can provide markers for these unconscious processes. This symposium will present evidence that ERPs can provide neurophysiological markers for unconscious processes elicited by subliminal stimuli. It will be shown that subliminal ERPs have a component structure (N1, P2, P3, a late negative peak) similar to supraliminal ERPs. In the studies to be reported, stimuli have been presented at the objective threshold (d'=0), the "gold standard" in subliminal research. The first paper will introduce the topic, provide a brief review of pertinent research, outline the methodological issues, and examine several theoretical implications for our understanding of conscious and unconscious processes. The second paper will present data on subliminal P3, showing its similarity to supraliminal P3 in terms of wave form, scalp topography, and as an index of psychologically relevant stimuli. The third paper will report on the relationships between ERP components N1, P2, P3, a late negative peak, and the connotative meaning of words as measured by the Osgood Semantic Differential in both subliminal and supraliminal ERPs. The fourth paper will present evidence that P3 can serve as a marker of learning in subliminal and supraliminal classical conditioning paradigms.
Subliminal ERPs: History, theory, methods
University of Michigan
The earliest research evidence of ERPs to subliminal stimuli was reported by Shevrin and Rennick (1967, Psychophysiology, 3, 381),Shevrin and Fritzler (1968, Science, 161, 295), and Libet, et al (1967, Science, 158, 1597). The first two studies demonstrated that a P2 component could discriminate between two visual stimuli presented at 1 ms. The third study, employing direct cortical activation, demonstrated that early somatosensory ERP components (approximately 100 ms) were correlated with subthreshold stimuli. Subsequently, Shevrin and co-workers published a series of studies replicating and extending the original work summarized in Shevrin (1973, Psychological Issues, 30, 56). Other laboratories have reported additional findings (Kostandov and Arzumanov, 1977, Acta Neurobiologiae Experimentalis, 37, 311; Barkoczi et al., 1983, Psychologia, 26, 1); Brandeis and Lehmann, 1986, Neuropsychologia 24, 151). Libet et al (1967) argued that later endogenous ERP components like P2 and P3 were associated with consciousness, a position also taken by Posner and Boies (1971, Psychological Review, 78, 391). Results from other laboratories (Shevrin, 1973; Kostandov and Arzumanov, 1977) presented evidence that both P2 and P3 were found in subliminal ERPs. Subsequent research to be reported in this symposium by Bunce, Bernat, and Wong have provided further evidence for subliminal P2 and P3 components. These findings suggest that unconscious processing can continue well below 300 milliseconds. ERPs to subliminal stimuli allow investigators to study concomitant unconscious processes rather than relying, as in most purely cognitive studies, on inferring unconscious processes from indirect effects such as priming.
P300 to subliminal stimuli: Looks like a duck, acts like a duck...
Scott C. Bunce1, Edward Bernat1, Howard Shevrin1, & Stephen Hibbard2
1University of Michigan, 2Pacific Graduate School of Psychology
Findings will be presented demonstrating that one endogenous ERP component, P300, can be used for the study of complex unconscious psychological processes. Three lines of evidence will be presented that argue for the utility of P300 in subliminal paradigms. First, there is a characteristic waveform that occurs approximately 300 ms post-stimulus, which will be illustrated through three-dimensional plots and grand averages. Second, when task and stimuli were identical across subliminal and supraliminal conditions, the P300 amplitude produced in a subliminal condition had the same scalp topography across electrodes (F3, F4, CzPz, P3, P4, Oz) as the P300 produced in the supraliminal condition (rank order correlation = 1.00). Third, P3 amplitude and latency can be used as an index of psychologically relevant stimuli. Research will be presented demonstrating that P300 can index individual differences in response to identical words, both as a function of traumatic life experience (early parental loss) and of subliminal versus supraliminal stimulus presentation. On the basis of previous research (Bunce et al., 1996, Psychophysiology, 33, S26), it was predicted that Loss participants would experience positive and intimate words as more negative than Controls, but only when presented outside awareness. P300 amplitude differentiated between positive and negative mood adjectives at supraliminal durations, but did not distinguish Loss from Control groups. At subliminal durations, however, a significant interaction indicated that whereas Control participants showed a greater P300 response to the negative words, P300 failed to discriminate between positive and negative words for the Loss group.
Subliminal and supraliminal ERPs as markers of connotative meaning
Edward Bernat1, Scott Bunce1, Howard Shevrin1, Michael Snodgrass1, & Steve Hibbard2
1University of Michigan, 2Pacific Graduate School of Psychology
Findings are presented demonstrating that visual ERPs elicited by subliminal and supraliminal stimuli differentiate pleasant and unpleasant connotative meaning as measured by the Osgood Semantic Differential Scale. Correspondence in structure between ERPs elicited at subliminal and supraliminal stimulus durations are demonstrated by comparing grand average plots. Two experiments are presented which demonstrate that ERP components (N1, P2, P3, a late negative peak) can discriminate between individually rated pleasant and unpleasant stimuli at both subliminal and supraliminal durations. In the first experiment with normal participants, a positive amplitude shift occurred across all components for unpleasant stimuli, at both subliminal (F[4,64]=2.50, p<.05) and supraliminal (F[4,64]=3.40, p<.02) durations. In the second experiment, involving social phobics, an interaction between stimulus duration and connotative meaning was found: supraliminally, a positive amplitude shift occurred for unpleasant words, while subliminally a positive amplitude shift occurred for pleasant words (F[4,64]=14.18, p<.001). Differences in subliminal response for the two samples are discussed in the light of the fact that participants in the second experiment were social phobics. These data demonstrate the similarity in structure of ERPs to subliminal and supraliminal stimuli, and show that standard ERP component measures can be an effective approach for investigating connotative meaning using supraliminally and subliminally presented stimuli.
ERP indices of unconscious processes in classical conditioning
Philip S. Wong1, Scott C. Bunce2, Edward Bernat2, Howard Shevrin2
1New School for Social Research; 2University of Michigan
We report new findings from two previous studies in which we found evidence for ERP correlates of unconscious processes involved in classical conditioning. Specifically, we report new P3 findings consistent with results reported by Bunce and Bernat (this symposium). In the first study (Wong et al., 1994, Psychophysiology, 31, 87), conditioning was established supraliminally and the effects measured subliminally. In the second study (Wong et al., submitted, 1997), conditioning was established subliminally and the effects measured supraliminally. In both studies we used a paired-stimulus paradigm with facial schematics, one unpleasant and one pleasant; the unpleasant face was linked to an aversive shock. We found that in the first study P3 varied as a function of face and conditioning. A significant interaction was present between pre-conditioning and post-conditioning subliminal durations across Cz, P3, P4, and Oz for P3 amplitude, F(1, 14) = 5.52, p<.03. A trend was also found for P3 latency for the same interaction, F(1, 15) = 3.44, p = .08. The direction for the amplitude interaction indicated that for the CS- habituation had occurred (F[1, 14] = 3.50, p<.08), while no habituation had occurred for the CS+. Latency increased for the CS+ from pre- to post, and decreased for the CS-, but neither effect was significant. These results are consistent with P3 results from the second study in which habituation occurred for the CS+ from pre-to post supraliminal durations. Thus, P3 demonstrated the effects of conditioning both sub- and supraliminally.
Review and funding of psychophysiological research: Perspectives,
opportunities, and strategies
Chair: Cindy M. Yee-Bradbury
Participants: Richard K. Nakamura, Niels Birbaumer, Margaret M. Bradley, Gregory A. Miller
Research funding can be critical to a program of psychophysiological research. The goal of this panel discussion is to familiarize researchers with current perspectives and judgments concerning the scientific review and support of psychophysiological research. Members of the panel will present prevailing views on grant applications, the review process, funding opportunities, and the prospects of receiving funds to support psychophysiological research. Perceptions as well as common misperceptions about psychophysiological research also will be discussed. Various perspectives are represented on the panel, ranging from that of funding agencies to those of experienced grant reviewers. Following presentation of key issues by members of the panel, the discussion will be opened up for questions and comments from the audience.
Perspectives on current restructuring of review at the National Institutes
of Health and funding priorities of the National Institute of Mental Health
Richard K. Nakamura
National Institute of Mental Health
Many aspects of the mechanisms for federal funding of research in the United States are undergoing review and reorganization. Dr. Richard Nakamura, Director of the Office of Science Policy and Program Planning at the National Institute of Mental Health (NIMH), will discuss the merger of NIMH study sections into the National Institutes of Health (NIH). An overview of the newly reconfigured study sections, and their relevance to psychophysiological research will be provided. Dr. Nakamura also will discuss the implications of this merger for NIH grant applications and review. He will address the development of NIMH funding priorities, and the criteria by which applications are judged. In addition, the perceived value and limitations of psychophysiological research, from the perspective of NIMH, will be considered.
Recent trends in psychophysiological research funding in Europe
University of Tuebingen
Multiple mechanisms exist for obtaining funds to support psychophysiological research in Europe. Drawing from experience with the European Community, Human Frontiers, German Research Society, and National Ministries in Europe, Prof. Dr. Birbaumer will discuss the review process and provide practical information that will maximize chances for obtaining funding. Comparisons will be made between various funding agencies. The likelihood of obtaining funds for psychophysiological research also will be considered.
Show me the $$$! Tips for preparing grant applications
Margaret M. Bradley
University of Florida
Whereas granting agencies typically provide specific guidelines for the preparation of a research application, certain additional features that can be important in the peer review process are not always explicitly mentioned and in fact can sometimes seem contradictory (e.g., achieving clarity and conciseness within a comprehensive and detailed discussion). Serving on the review side of the granting process allows one to become more familiar with different methods for successfully balancing these apparently conflicting objectives and for preparing a successful application. In addition, whereas the relationship between reviewer and investigator is sometimes viewed as adversarial, serving on a National Institute of Mental Health initial review group (IRG) committee also makes it apparent that the reviewer often acts as the investigator's advocate in the review process. In this case, the success of presenting and defending a research proposal to the larger committee is dependent to a large extent on the information available in the grant application. Thus, the investigator's task is not only to clearly describe and justify the proposed research but also to provide the reviewer with as much information as possible that will assist in supporting the application in the larger committee meeting. These and other suggestions gleaned from IRG service will be discussed in this session.
Outsiders inside: Some notes on Initial Review Group culture
Gregory A. Miller
University of Illinois at Urbana-Champaign
The experience of serving on a National Institute of Mental Health Initial Review Group and reviewing federal grant applications is valuable in many ways. One reads state-of-the-art literature reviews that are more or less in one's area, one watches paradigms in the making, one learns how to read and thus how to write a grant application, and one is paid (precious little!) to argue constructively with smart colleagues about the merits of proposed protocols and even research areas. Accompanying this intensive, advanced seminar experience are some windows into how federal funding agencies work, how they see themselves, and how they see their various constituencies. Experiences and perspectives from serving on several review groups will be shared.
Psychophysiological studies of biobehavioral mediators of risk
for alcohol abuse
Chair: Peter R. Finn
Participants: Alan R. Lang, Jeanette Taylor, Howard L. Cohen, Peter R. Finn
Discussant: Kenneth J. Sher
Alcoholism is a heterogeneous disorder with a number of associated risk and vulnerability factors such as a positive family history of alcoholism, antisocial/disinhibited behavior, and differential responsivity to alcohol. Although it is clear that each of these factors is associated with increased risk for the disorder, the precise mechanisms by which they mediate risk are unclear. Current etiological theories are typically biobehavioral in nature and focus on the role of individual differences in vulnerability (e.g., a genetic diathesis) in the development of substance abuse. Psychophysiology provides a set of methods and measures that can open a unique window for identifying biobehavioral mediators of risk for alcohol abuse. The purpose of this symposium is to present data from range of psychophysiological studies of biobehavioral mediators of risk with an emphasis on the interface between substance abuse and antisocial/disinhibited behavior. The symposium includes reports of studies that include autonomic, somatic, and electrophysiological measures and paradigms representing a range of approaches to investigating risk factors in substance abuse.
Drinking, emotional response, and disinhibition: Startle-probe studies
implicating complex cognitive-affective processes in the connections.
Alan R. Lang & Christopher J. Patrick
Florida State University
A multidimensional conceptualization of emotion incorporating multilevel brain processes provides enhanced opportunities for understanding connections between alcohol intoxication and emotional response, and perhaps behavioral disinhibition that sometimes accompanies them. Three investigations of drugs and affect, all incorporating startle-probe methodology to index emotional valence, highlight the importance of multidimensional assessment of emotion by yielding findings at variance with those emanating from earlier, arousal-focused research apparently supporting the thesis that alcohol intoxication is routinely accompanied by tension reduction or a dampening of response to stress. Key results indicate that, whereas diazepam selectively reduces startle potentiation associated with aversive stimuli, alcohol merely reduces overall reactivity without having a significant impact on affectively modulated startle. Furthermore, in a study of how alcohol and pleasant distracters affect startle reactions under threat conditions, diminished startle potentiation was observed only in the presence of both alcohol and distraction. This suggests that the compromising of higher-order cognitive processes (e.g., those involved in simultaneous attention to competing stimuli of differing salience) by alcohol may be critical to any stress reduction associated with drinking. Speculative extrapolation from these findings to the conditions that may mediate alcohol-related behavioral disinhibition (e.g., aggression) are intriguing and may have some parallels in distinctions between classic psychopathy and simple antisociality.
Electrodermal response modulation: Could it index a protective factor against substance dependence in adolescent males?
Jeanette Taylor, Scott R. Carlson, William G. Iacono, & David T. Lykken
University of Minnesota
Adolescent males may exhibit a number of disinhibited behaviors including antisocial behavior and substance use. The development of substance dependence among male adolescents may result from a combination of factors including persistent substance use despite predictable aversive consequences. Poor electrodermal response modulation to a predictable aversive stimulus may index a constitutional factor related to the development of substance dependence. As such, we expected male adolescents with poor electrodermal response modulation to a predictable aversive stimulus to have more symptoms of DSM-III-R substance dependence than those with good modulation. As part of the ongoing Minnesota Twin Family Study, we recorded skin conductance responses (SCRs), heart rate (HR), and anticipatory skin conductance level (SCL) and non-specific electrodermal fluctuations (NSFs) from 75 16- to 18-year-old males during five 100-s trials in which a 2-s 90 dB white noise blast was either unpredictable or temporally predictable. The modulation index reflected the percent increase/decrease in SCR when the stimulus was made predictable. The 75 boys fell into three equal-sized modulation groups. Good modulators had significantly fewer symptoms of Alcohol and Nicotine Dependence than Moderate and Poor modulators. Mean anticipatory SCL did not differentiate the modulation groups, but Good modulators had significantly more anticipatory NSFs than Poor modulators. Finally, mean HR did not differentiate the modulation groups. Given the similarity in symptom counts between the Moderate and Poor modulators, it could be that good SCR modulation indexes a protective factor against substance dependence in adolescent males.
Electrophysiological correlates of disinhibition in individuals at high
risk to develop alcoholism
Howard L. Cohen, Bernice Porjesz, & Henri Begleiter
SUNY Health Science Center-Brooklyn
For the past twenty years our laboratory as well as several others has repeatedly observed a significantly lower amplitude of the P3 component of the Event-Related Potential (ERP) in both abstinent alcoholics and the offspring of alcoholics. It has been demonstrated that this important finding is not the result of excessive alcohol abuse but is highly related to family density of alcoholism. We have recently postulated that this significantly reduced P3 component may indicate increased central nervous system (CNS) disinhibition. Loss of inhibitory control is not only prevalent in abstinent alcoholics, but also is present in children of alcoholics. It is well-established that male offspring of alcoholics are more likely to display undercontrolled behavior, and children with conduct disorders are more likely to have a positive family history of alcoholism. Thus, there is evidence that disinhibitory processes may underlie both electrophysiological deficits and behavioral dysfunction in alcoholics and their offspring. In our laboratory we have been assessing ERP correlates of disinhibition with novel neurophysiological paradigms. The results of these electrophysiological studies suggest that aspects of brain dysfunction (i.e. lack of differential inhibition) may be involved in a predisposition for alcoholism.
Biobehavioral mediators of early-onset, antisocial, alcohol abuse in
men and women: Response to threat and passive avoidance learning
Peter R. Finn, Linda Rorick, & Joseph Steinmetz
Substantial evidence exists for the validity of an early-onset, antisocial, subtype of alcoholism. Early-onset alcoholism is associated with severe symptoms, poor treatment response, more alcoholic relatives, impulsivity, novelty seeking, and low harm avoidance (Cloninger, 1987). Studies indicate that low harm avoidance and high novelty seeking in young boys are predictive of adolescent-onset alcohol abuse. This literature presents 2 major issues and questions: (i) what is the role of gender, and (ii) what biobehavioral mechanisms mediate risk for this type of alcohol abuse. Much of the research is focused on males, and relies on self/behavioral report of symptom phenotypes. This study assessed the role of disinhibitory processes, as evidenced by low electrodermal (EDA) and fear-potentiated startle response to threat and deficits in passive avoidance learning, in early-onset (less than 20 years), antisocial alcoholism. The data revealed that early-onset alcoholism was associated with high levels of antisocial traits, low harm avoidance (in men more than women), increased venturesomeness and impulsivity, and a family history of alcoholism. EDA hyporeactivity was associated with low harm avoidance, a family history of alcoholism, and early-onset alcoholism. Decreased fear-potentiated startle was related to low harm avoidance and increased venturesomeness but only in men. In men, but not women, deficits in passive avoidance learning were also associated with antisocial traits, a family history of alcoholism, early-onset alcoholism, EDA hyporeactivity, and low harm avoidance. In women, early-onset alcoholism and antisocial traits were associated with good passive avoidance learning. Results are discussed in terms of a disinhibitory predisposition to alcoholism and potential gender differences in phenotype manifestation.
Chair: Louis G. Tassinary
Participants: Rosalind W. Picard, Frederic I. Parke, Stephen Grossberg
Discussant: Louis G. Tassinary
Synthetic emotions are a perennial topic of conversation in philosophy and science fiction. The fields of affective computing, character animation and the mathematical modeling of cognitive and neural systems have recently become sufficiently advanced to where it is possible to broach the synthesis of emotion in a scientifically credible manner. Not unlike how the use of model systems and computational neuroscience have fundamentally changed cognitive science, advances in these fields are poised to change the nature of affective science. Our three speakers will provide reports on their extensive forays into each of these areas. First, Picard will describe recent work on attempts to make computer-laden environments more "human-like" though the addition of novel sensors and effectors, as well as through acquiring "emotion-like" states. Second, Parke will review the state-of-the-art in computerized facial animation, an area at the forefront of computerized character animation. Finally, Grossberg will provide a tutorial on a type of model for adaptive systems generally that may provide the foundation for understanding and ultimately constructing autonomous synthetic agents that react "emotionally" and learn from experience. Following discussion by the chair, questions and comments from the audience will be invited.
Rosalind W. Picard
Massachusetts Institute of Technology
Affective computing is computing that relates to, arises from, or deliberately influences emotions. There is evidence that computers with emotion-like mechanisms could be more flexible and rational in tasks such as planning and decision making than could non-affective machines, so that soon computers may also be given the ability to "have emotions", or at least emotion-like mechanisms. Computers are also beginning to acquire the ability to express emotions and to recognize emotional expressions. It is known that emotions are a natural part of human-computer communication; consequently, it is increasingly important for computers to learn how to perceive the emotions a user is expressing. For example, software agents that try to learn a user's preferences could be less of a burden to their users if they could recognize whether a user liked or disliked their most recent action. We are developing wearable computers, equipped with physiological sensors, which can be in long-term personal contact with their wearer, learning how he or she responds in a variety of natural situations. We are also developing pattern recognition algorithms that can be applied to combinations of physiological signals in an effort to find patterns consistent with various emotional states. The plan is that given physiological patterns, together with high-level knowledge about the user's situation, then a computer could learn to recognize his or her probable emotions. I will present our research in this new area, focusing on sensing, signal processing, and pattern recognition problems as well as on some emerging applications.
Computer facial animation
Frederic I. Parke
Facial animation is a major aspect of computer based character or "actor" animation. Facial animation is also a part of recent user interfaces which use anthropomorphic agents or avatars. In both uses, capable facial animation must be able to express and convey "synthetic emotion." Development of computer facial animation began in the early 1970's, with most development occurring in the last decade. Facial animation is based on the development of geometric models for the various facial features. These are based on the anatomy of the face - facial skeleton, muscles, skin and interior structures of the mouth such as the tongue. Facial models are often concerned with capturing the likeness of specific real faces. This is done by digitizing the shape of real faces using one of several three-dimensional surface measuring techniques. Animation is accomplished by changing facial shape over time using interpolation, muscle based deformation, or surface parameterization techniques. Facial models usually incorporate the mechanics of facial tissue. They can also include vascular skin color effects. Successful facial models support a wide range of expressions including the universal expressions: surprise, fear, disgust, anger, happiness, and sadness. Speech synchronized animation involves matching speech postures to a spoken soundtrack. Complete speech animation includes coarticulation, expression overlays and eye actions. Current goals in facial animation research include the development of models with expression abstraction layers, higher level controls, and ultimately synthesized behaviors and personalities.
How do reward, emotion, and attention help to shape brain decisions?
This talk will provide a self-contained introduction to neural models that are being developed to explain how cognitive and emotional processes interact in the brain. These models clarify how cognitive-emotional interactions help to focus attention on important objects and events, and influence the affective decisions that we make in our daily lives. The results clarify a large body of psychophysiological data concerning classical and instrumental conditioning, decision making under risk, and various mental disorders, including examples of schizophrenia, juvenile hyperactivity, depression, and Parkinson's disease. A key theme in the models is how opponent processes help to control reinforcement learning in response to positive and negative reinforcers. Affective antagonist rebounds are triggered in these opponent circuits when reinforcers are suddenly removed, or when other novel events occur. These rebounds can be traced to the action of chemical transmitters that are slowly inactivated, or habituate, in an activity-dependent way. Inverted U properties are also found that help to differentiate symptoms of overaroused vs. underaroused depression. Paradoxical data concerning decision-making under risk, including the gambler's paradox and preference reversals naturally emerge from these circuits as emergent properties. Cognitive-emotional interactions that include these opponent circuits clarify how learning can distinguish between contingencies that are causal, vs. accidental correlations in the environment. In particular, it is shown how unexpected consequences can be used to actively extinguish otherwise long-lasting memories. The model circuits are interpreted in terms of thalamo-cortico-amygdala-hippocampal interactions in the brain.
Steady-state evoked potentials: New methodological approaches
Chair: Matthias M. Mueller
Participants: Terence W. Picton, Scott Makeig, Livio Narici, John W. Rohrbaugh, Matthias M. Mueller
The steady-state response (SSR) is a continuous brain response that is elicited by a repetitive stimulus presented at a fixed frequency. The SSR can be recorded from the scalp as a nearly sinusoidal oscillatory waveform having the same fundamental frequency as the driving stimulus and often including higher harmonics. Steady-state responses have been reported in the acoustic, visual and somatosensory modalities. Up to today the mechanism underlying the generation of steady-state responses is still under debate. However, steady-state responses serve as a important tool to investigate normal and abnormal visual processing and cognitive processes including attention, memory, and decision making. This symposium will discuss the latest methodological approaches to analyzing and localizing theses responses, to gain more information on the underlying mechanisms. Interactions between separate brain regions will also be discussed by means of steady-state responses, and clinical applications will be demonstrated. In addition, it will be shown that high frequency visual evoked steady-state responses are modulated by spatial attention, indicating that steady-state responses serve as an useful tool to investigate cognitive processes. Given the increasing interest in research on steady-state responses, and the growing evidence that SSRs provide important information for understanding basic brain functioning, this symposium will provide an opportunity to demonstrate and critically discuss (a) the progress the field has gained so far and (b) avenues for research in the future.
Studying cerebral function with steady-state responses
Terence W. Picton
University of Toronto
Steady-state evoked potentials possess several features that make them useful tools for evaluating cerebral function. First, unlike temporal waveforms, steady-state responses do not require the experimenter to identify peaks prior to measurement. The responses can be easily and objectively measured in terms of the real and imaginary components of the response (or amplitude and phase) at the frequency of stimulation or some harmonic thereof. These two-dimensional measurements can be distinguished from noise using well defined statistics and can thus be used as objective indices of sensory activation. Since the real and imaginary components are independent, they can be directly submitted to source analysis, which shows sources that are mainly specific to the modality of the stimulus. Second, steady-state responses can be continuously and consistently recorded over intervals lasting from seconds to minutes. This allows easy comparison to measurements of cerebral blood flow which have a similar time-course. These temporal characteristics also allow steady-state responses to monitor fluctuations in cerebral activity related to arousal or attention. Auditory 40 Hz responses are particularly susceptible to anesthesia and can be used to monitor anesthetic unconsciousness. Selective attention can be studied using two or more trains of stimuli, each of which can be attended or ignored, and each of which can be analyzed separately. Third, the steady state responses may be able to evaluate various rhythmic interactions in the human brain by driving rhythms that are important to cognition but too evanescent to study during normal activation.
Independent component analysis of steady-state responses
Scott Makeig1,2, Tzyy-Ping Jung1,3, Te-Won Lee3, & Terrence J. Sejnowski3
1Naval Health Research Center-San Diego, 2University of California-San Diego, 3The Salk Institute-La Jolla
Independent Component Analysis (ICA) is a new signal processing technique for decomposing spontaneous or evoked EEG and MEG data into temporally independent and spatially fixed components. The scalp distribution of the auditory steady-state response near 40 Hz appears to sweep from the front to the back of the scalp every cycle. ICA decomposes this apparent movement into the sum of at least two bilateral components with different scalp distributions and phase lags. ICA accounts for the transient perturbations in SSRs produced by experimental events using the same components producing the SSR, supporting the hypothesis that these transient (CERP) perturbations represent modulation of the ongoing response. Application of ICA algorithms capable of both sub-Gaussian and super-Gaussian components will be presented and psychophysiological implications of new blind decomposition techniques discussed.
Repetitive sensory stimulation and cortical rhythms: Neuromagnetic studies
University of Rome
Cortical responses to repetitive sensory stimulation are studied by delivering a short train of stimuli separated by pauses. They are analyzed both during stimulus delivery and pauses, while scanning the stimulus rate within the frequency band of interest. This "Frequency Responsiveness Procedure" was applied to healthy subjects during two different investigations, in Rome (CNR-IESS, 28-channel neuromagnetic sensor, visual and somatosensory modalities) and in Helsinki (LTL-Brain Research Unit,122-channel whole scalp neuromagnetometer, visual somatosensory and auditory modalities).Electric 0.3-ms pulses were delivered to the median nerve at an intensity above motor threshold. 30-ms light pulses were presented with LEDs at 5-7 degrees eccentricity in the left hemifield. 15-ms monaural noise bursts were used for the auditory modality. Stimuli were delivered in separate sessions in trains of 14-15 stimuli, interleaved with 1.3-1.6 s pauses. Stimulus rates within the trains varied from 6 to 14 Hz.Three effects were observed in relation to repetitive stimulation: i) activity driving (modality specific); ii) rhythm suppression (also in non-modality specific areas); iii) minor but consistent wide band, activity suppression over the whole cortex. Different activities present in the same frequency band were discriminated on the basis of their responsiveness to repetitive stimulation. The genesis of the measured visually driven activity (composition of evoked responses vs. driving of the intrinsic rhythms) appeared to be related to the amount of posterior resting rhythm. Source localization was performed whenever possible.
Event-related perturbations in steady-state rhythms
John W. Rohrbaugh, Erik Sirevaag, & Andrei Vedeniapin
Washington University School of Medicine
Event-related perturbations in steady-state auditory rhythms have been described by a number of investigators as signs of transient cognitive and attentional processes. The perturbation response is of particular interest because it can be obtained nonobtrusively in response to probe stimuli under conditions in which it does not interfere with performance of primary tasks. These findings and interpretations will be reviewed. Data from a study of the origins of the auditory steady state rhythm will presented, as will speculations regarding the character of the event-related perturbations in rhythm phase and amplitude. These findings are consistent with an interpretation of the rhythm in terms of hybridized middle latency components, with lability of the P1 response contributing principally to the perturbations of the rhythm. Data from a study of chronic alcoholics will be presented to illustrate possible clinical applications of the phenomena.
High frequency steady-state visual evoked potentials are modulated by
spatial selective attention
Matthias M. Mueller1, Terence W. Picton2, & Steven A. Hillyard3
1University of Konstanz, 2 Rotman Research Institute-North York (Canada), 3University of California-San Diego
To investigate the attentional modulation of high frequency steady-state visual evoked potentials (SSVEPs), subjects attended to one of two "bars", each of which consisted of a linear array of five bicolor (red, green) LEDs flickering in the left (at 20.8 Hz) and right (at 27.8 Hz) visual hemi-field. 1296 ms after flickering onset, an attention-directing cue informed the subject whether to attend to the left or the right bar. Subjects were instructed to fixate on a central point and to detect targets within the bar that was indicated by the cue for a period of 10 s per trial by pressing a button. Targets were defined as a change in color of the most upper and most lower LED. EEG was recorded from 30 scalp electrodes. SSVEPs to the concurrent left and right field flickers were averaged separately in the time domain by using a moving window technique. Amplitude was obtained by means of a FFT at the appropriate frequency. Overall SSVEP amplitudes were larger for the 20.8 Hz flicker than the 27.8 Hz flicker (p <0.001). With attention, the SSVEP amplitude increased significantly for both the right and the left bar (p <0.01). This increase was greater over the contralateral hemisphere (p <0.05), and moreso for posterior than anterior electrode sites (p <0.05). The present results suggest that SSVEPs might serve as an useful tool to study visual attention.
The role of cortisol in memory, attention, and emotion
Chair: Louis A. Schmidt
Participants: Sonia Lupien, Melissa Goldberg, Louis A. Schmidt
Discussant: Jay Schulkin
The purpose of this symposium is to bring together researchers from disparate literatures in order to better understand the multiple roles of cortisol in cognitive and emotional processes in humans. We will address several questions: 1) does elevated cortisol impair memory recall for specific classes of stimuli (e.g., neutral objects) and enhance memory recall for other classes of stimuli (e.g., fear-related objects)? 2) what are the functional aspects of elevated cortisol in particular personality profiles (e.g., fearful and shy individuals)? and 3) what are the developmental implications associated with current work in this area in relation to the aging brain and cognitive and emotion processes over the lifespan? Sonia Lupien will present data on the relation between elevated cortisol and memory performance (implicit and explicit) in young and elderly human adults. Melissa Goldberg and Nathan Fox will present data in adults on the different effects of cortisol on memory and attention. Louis Schmidt and Nathan Fox present data from studies of children in which elevated endogenous cortisol levels are linked to fear-potentiated startle responses and shyness during the preschool and early school age years. They also present data on the relation between exogenous administration of high doses of cortisol and the startle response, and they speculate on the function of elevated cortisol in shy and fearful children and adults. Jay Schulkin, known for his work on the effects of cortisol on cognitive and affective processes, will integrate and facilitate discussion on the three papers.
Cortisol and memory
Douglas Hospital/McGill University
We previously reported that 38% of healthy elderly adults show a significant year-to-year increase in cortisol levels, while 47% present a moderate year-to-year increase and 16% present a year-to-year decrease of cortisol levels with years. We reported a significant negative correlation between increase in cortisol levels with years and decreased explicit memory performance. Implicit memory was not correlated with increase in cortisol levels in this population. Confirmation of the detrimental effects of increased levels of corticosteroids on hippocampal function in this population was recently obtained in studies showing that elderly subjects presenting a significant year-to-year increase in cortisol levels with explicit memory impairments show a significant 17% reduction of hippocampal volume as measured by magnetic resonance imaging when compared to the other elderly subjects. We now report data on 8-year cortisol secretion in 12 healthy elderly human subjects, and show that the function relating cortisol secretion and time in these elderly subjects is not linear as originally postulated, but rather fits a curvilinear function with a three-year wave-cycle of cortisol secretion that slowly increases with each cortisol/year peak. Analysis of 4-year cortisol secretion and explicit/implicit memory function in other elderly subjects further showed that the curvilinear increase observed in cortisol secretion in later life is closely related to a curvilinear decrease in explicit memory function. This suggests that there is some degree of reversibility in the cognitive deficits generally reported in aged human populations.
Effects of cortisol on memory and attention
Melissa Goldberg & Nathan A. Fox
University of Maryland-College Park
We investigated in normal human adults the cognitive effects of prednisone (160 mg daily; n=9) versus placebo (n=6) in a double blind procedure. Treatment lasted for 4 days. On day 4, subjects performed two tasks: attention and memory. (1) In a visual attention task, subjects indicated which of two shapes appeared in the periphery 400 msec after a central cue, with those shapes surrounded by compatible or incompatible distractors. (2) In a memory task also on day 4, subjects studied a tray of 25 items for 1 min and then had 2 min to recall the items; on day 9, subjects were asked to recall the items presented on day 4. Results on the attention task showed the groups did not differ with respect to the effects of the cue and/or the distractors (ANOVA on RT, interactions with group, all p's >.10). This suggests that prednisone treatment may not interfere with the abilities to shift attention or maintain focused attention. On the memory task, although subjects in the prednisone group were initially (day 4) able to remember as many items as controls (12.8 versus 13.3, respectively, t-test, p > .10), 5 days after the treatment ended (day 9), they were impaired in their ability to remember as many items (7.9 versus 11.1, t-test, p <.001). The results to date agree with reports in the literature that brief prednisone treatment interferes with delayed recall information learned during treatment and not visual attention.
The role of cortisol in fear-potentiated psychophysiological responses
in human adults
Louis A. Schmidt & Nathan A. Fox
University of Maryland-College Park
A number of studies of animals and humans suggest that cortisol may play a role in the maintenance of fear responses. The purpose of this paper will be to present data from a series of developmental studies in which the relation between elevated endogenous and exogenous cortisol and fear responses have been examined. In study 1, we found a significant relation between shyness and elevated morning salivary cortisol. Shy preschoolers displayed high morning salivary cortisol levels compared with their nonshy counterparts. In study 2, we found modest relations between high salivary cortisol exhibited in the laboratory and the fear-potentiated startle response in middle childhood. Seven year-olds who displayed high laboratory salivary cortisol levels exhibited a heightened startle amplitude in response to an affective social challenge task. In study 3, we administered high doses of prednisone (160 mg) daily for four consecutive days to 12 undergraduate males and a placebo to 12 undergraduate males in a double blind study. On day four, we presented the Lang slide paradigm to the 24 subjects and examined their fear-potentiated startle responses while viewing the slides. These data will be presented and discussed in relation to previous findings from our laboratory on the role of cortisol in the regulation of emotion.
Psychophysiology: The Shape of its Future
Chair: Emanuel Donchin
Participants: Richard J. Davidson, Emanuel Donchin, Edward S. Katkin, Peter J. Lang
Discussants: Marta Kutas, Gregory A. Miller
The participants in this panel serve on the latest version of the Committee on the Future of Psychophysiology. In this panel we plan to share with the membership our thoughts and report on our actions. We will particularly focus on our response to the challenge presented by some officials who suggest that with the advent of "neuroimaging" we have reached a stage where "traditional psychophysiology" has become effectively obsolete. It is perhaps no surprise that the committee did not find this argument compelling. Exactly how to deal with this view will be one subject of the panel presentation. Other challenges and opportunities facing the field will also be discussed.