Individuals with posttraumatic stress disorder (PTSD) have been found to show several event-related brain potential (ERP) abnormalities including reduced target P3b amplitude, P50 suppression, and P2 amplitude/intensity slope. Female Vietnam nurse veterans with (n = 29) and without (n = 38) current PTSD completed P50 paired-click, three-tone “oddball” and four-tone stimulus-intensity modulation procedures. Opposite to previous findings, the current PTSD group had larger target P3b amplitudes and increased P2 amplitude/intensity slopes. Reduced P50 suppression was associated with increased severity of general psychopathology, but not with PTSD diagnosis. Findings suggest that target P3b amplitude and P2 amplitude/intensity slope abnormalities reflect different pathophysiological processes. Future research is needed to determine whether the opposite ERP abnormalities observed in this PTSD sample reflect gender-, trauma-, or sample-specific findings.

The present study was undertaken to determine whether aversiveness contributes to startle potentiation in anticipation of affective pictures above and beyond the effects of emotional arousal. Further, participants high in trait anxious apprehension, which is characterized by worry about the future, were expected to show especially pronounced anticipatory startle responses. Startle blink reflex was measured during warning stimuli that predicted the valence of ensuing aversive/unpleasant, pleasant, or neutral pictures. Startle magnitude was larger in anticipation of aversive than of pleasant pictures and smallest in anticipation of neutral pictures. Enhanced startle potentiation was not found in anxious apprehension subjects. These data suggest that the aversive nature of stimuli contribute to the potentiation of startle above and beyond the effects of emotional arousal, which may be a universal phenomenon not modulated by individual differences.

The capacity of working memory has been suggested to differ among people and these differences affect performance in a wide variety of cognitive tasks. This study explored electrophysiological correlates of individual differences in working memory capacity by means of event-related potentials. Thirty-four healthy students performed two- and five-choice reaction time tasks. In the two-choice reaction time (2CRT) task, two digits (3 and 7) were presented visually with probabilities of .20 and .80. In the five-choice reaction time (5CRT) task, five digits (3, 4, 5, 6, and 7) were presented equiprobably in a random order. Participants were required to press a button corresponding to each digit with a different finger. Working memory capacity of each participant was assessed by the reading span test originated by M. Daneman and P.A. Carpenter (1980). Participants with high reading span produced larger P300s than did persons with low reading span in the 5CRT task, but the difference was not significant in the 2CRT task. It had been suggested that individual differences in working memory capacity would affect initial stages of information processing as early as 300 ms after stimulus onset.

The effects of global and feature-specific probabilities of auditory stimuli were manipulated to determine their effects on the mismatch negativity (MMN) of the human event-related potential. The question of interest was whether the automatic comparison of stimuli indexed by the MMN was performed on representations of individual stimulus features or on gestalt representations of their combined attributes. The design of the study was such that both feature and gestalt representations could have been available to the comparator mechanism generating the MMN. The data were consistent with the interpretation that the MMN was generated following an analysis of stimulus features.

The influence of the level of prestimulus alpha phase synchronicity on the N100 component and reaction time (RT) was examined, in target auditory oddball data from 25 normal subjects. Alpha phase synchronicity is a new measure consisting (for a given stimulus presentation) of the angular or circular variance of the alpha phase at stimulus onset across the parieto-occipital sites. The lower the angular variance, the higher the phase synchronicity (the more closely in phase the alpha activity across these sites) and vice versa. Subaveraged event-related potentials (ERPs) were formed for high and low prestimulus alpha phase synchronicity stimulus presentations. N100 amplitude was significantly greater in the high than the low phase synchronicity subaverages. In addition, RT was significantly reduced in the high prestimulus alpha phase synchronicity cases. Alpha phase synchronicity reflects an aspect of brain state that influences subsequent stimulus processing.

We studied the relationship of respiratory sinus arrhythmia (RSA) to the co-activation of autonomic and facial expressive responses in 37 adult men during Rorschach testing. Interbeat interval (IBI), electrodermal activity, and facial electromyography were recorded continuously during the experiment. Prevailing mood and variability in the experience of valence and arousal were also measured. Bivariate intraindividual time series analysis was used to quantify spontaneously coupled phasic physiological responses. The results suggested that (a) spontaneous autonomic and expressive responses tend to parallel in time; (b) baseline, task-level, and task-induced change of RSA were positively related to coupled autonomic–expressive responses, a change in mood toward a more energetic state, and a tendency to have more variability in the emotional experience during the task; and (c) especially cardiac–expressive response coupling was related to mood change. It is concluded that the vagal system is related to the control of facial muscle activity and may mediate both tonic and phasic emotion-related changes in IBI. The role of phasic intraindividual response patterns in emotional and social behavior is highlighted.

To determine if the inability to take advantage of the predictability of an aversive stimulus to diminish its psychological impact reflects a deficit in inhibitory control related to the development of substance dependence, we recorded skin conductance responses (SCRs), heart rate (HR), and anticipatory electrodermal nonspecific fluctuations (NSFs) from 175 16–18-year-old boys when a white noise blast was either unpredictable or temporally predictable. Compared with boys who had moderately reduced or augmented SCRs to predictable blasts (moderate and poor modulators, respectively), boys whose SCRs were greatly reduced (good modulators) had fewer symptoms of alcohol and nicotine dependence and more anticipatory NSFs. HR appeared to index an active coping response for good and moderate modulators. The autonomic response pattern evident for good modulators may index an inhibitory control mechanism protecting them from developing substance dependence.

P300 amplitude and reaction time (RT) are strongly affected by the sequence of events preceding the eliciting stimulus. Sommer, Leuthold and Soetens (1999) found that robust sequential effects in P300 amplitude could be dissociated from more variable sequential effects in RTs. However, global changes in P300 amplitude and topography gave rise to the suggestion that sequential effects are specific for a subcomponent of P300 that is separate from and anterior to the classical parietal P300. Here, confirming evidence for dissociable subcomponents of P300 is reported from two experiments. Independent component analysis separated a centrally distributed sequence-sensitive subcomponent from a more parietal subcomponent. Subsequent dipole source analysis indicated a deep mesial source for the sequence-sensitive subcomponent. Overlap with reafferent somatosensory activity appears to be responsible for an apparent lateralization of this component towards the hemisphere ipsilateral to the responding hand.

The effects of global and feature-specific probabilities of auditory stimuli were manipulated to determine their effects on the mismatch negativity (MMN) of the human event-related potential. The question of interest was whether the automatic comparison of stimuli indexed by the MMN was performed on representations of individual stimulus features or on gestalt representations of their combined attributes. The design of the study was such that both feature and gestalt representations could have been available to the comparator mechanism generating the MMN. The data were consistent with the interpretation that the MMN was generated following an analysis of stimulus features.

Though many studies suggest that fine acoustic details fade from memory after 15 s or even less, everyday experience tells us that the voice of a person or a musical instrument can be recognized long after it was last heard. We wished to determine whether tones leave a lasting memory trace using an experimental model of implicit recognition and testing whether exact pitch information can be retrieved even after 30 s. Event-related brain potentials demonstrated the survival of an accurate representation of tone pitch in the auditory cortex. This result provides a link between short-duration buffering and permanent storage of acoustic information.

The difference in attention and cognitive performance between 26 hypotensive (systolic blood pressure < 100 mmHg and diastolic blood pressure < 60 mmHg) and 22 normotensive female university students was assessed. Attention was examined with contingent negative variation (CNV) recorded using light and tone as S1 and S2. Cognitive performance was assessed by free recall of a list of words and two German tests of cognitive speed performance and sustained attention: Zahlen-Verbindungs-Test and d2. The hypotensive participants demonstrated a lower increase in negativity on the CNV. Moreover, in the free recall test, hypotensive individuals remembered fewer words, in comparison with normotensive subjects. Scores for hypotensive individuals on the Zahlen-Verbindungs-Test and d2 were also lower. No difference was found in reaction times to imperative stimuli (S2).

M.E. Smith (1993) obtained event-related brain potentials (ERPs) from subjects performing a recognition memory task using “remember” (R) and “know” (K) judgments, and reported observing in the ERP a “neurophysiological manifestation of recollective experience” as a difference between the positive waveforms elicited by stimuli that yielded R and K judgments. We replicated his experiment and examined the componential structure of the R>K effect in two ways. First, we found that correction for P300 latency jitter eliminated the effect reported by Smith. Second, the application of principal component analysis indicated that the positive waveform elicited by the words in the test list was a P300. These analyses do not support the hypothesis that there is a new component (the “memory-evoked shift”) that is a specific manifestation of recollection.

White and Yee (1997) found that normal suppression of the P50 component of the event-related potential was disrupted during a paired-click paradigm when nonpsychiatric subjects performed mental arithmetic (MA) problems aloud, concurrently with the presentation of auditory stimuli. In fact, the degree of disruption reflected in the P50 suppression ratio fell within the range that is typically observed in schizophrenia patients. The present study was conducted to clarify the processes that might underlie the apparent disruption of P50 suppression during performance of an oral MA task. Participants completed a series of tasks designed to examine the impact of competing cognitive activity, competing auditory stimulation, muscle activity, and acute psychological stress on P50 amplitude and P50 suppression. Results suggested that psychological stress and heightened facial muscle activity may exert modulatory effects on P50 suppression.

Event-related potentials were recorded from 11 subjects after ingesting caffeine (250 mg) or placebo. Subjects were instructed to attend selectively to stimuli with a specified color (red or blue) in order to react to the occurrence of a target within the attended category. Reaction times revealed faster responses for the caffeine condition, whereas no differences in strategy were observed. Color attention effects were identified as frontal selection positivity, occipital selection negativity, and N2b, whereas target detection was reflected in P3b. Effects of treatment were found as a more positive-going frontal P2 component in the caffeine condition. In addition, an interaction between attention and treatment could be observed on the N2b component. This pattern of results suggests that caffeine yields a higher overall arousal level, more profound processing of both attended and unattended information, and an acceleration of motor processes.

The aim of this study was to examine the relationship between force and rate of force development with electroencephalogram correlates. The primary question was whether the different components of movement related potentials (MRPs) were related to specific properties of force output while subjects performed index finger force production tasks. The peak force and rate of force development (e.g., a product of peak force over time-to-peak force) were manipulated, and the effects of these manipulations on components of MRPs preceding and accompanying force production tasks were examined. The hypothesis was that the rate of force development, rather than level of force itself, would directly influence the later component of MRPs. Consistent with this hypothesis was the finding that the amplitudes of MRP components preceding (MP) and accompanying (MMP, MTP) finger force production movements were significantly correlated with force development rate.

Psychophysiological “preparatory” responses may or may not depend on a focused expectation of when a stimulus will occur. Changes in heart rate, pupillary diameter, and brain potentials were examined during trials in which foreperiod of a simple reaction time (RT) task was fixed or unpredictable. Trials were also included in which stimuli for the speeded motor reaction were triggered by psychophysiological changes occurring spontaneously in the foreperiod. Thirty-two college-aged volunteers equally divided by gender participated in the experiment. Reducing expectancy, by using nonaging foreperiods, eliminated transient prestimulus psychophysiological responses but failed to eliminate slow changes over the foreperiod—slowing of heart rate, dilation of the pupil, and cortical surface negativity. Triggering the reaction stimulus by physiological changes did not influence RT. Correlations between psychophysiological changes in the foreperiod and between these changes and RT were generally low. The results were consistent with a multiprocess view of preparation.

The aim of this study was to assess the error made by violating the assumption of stationarity when using Fourier analysis for spectral decomposition of heart period power. A comparison was made between using Fourier and Wavelet analysis (the latter being a relatively new method without the assumption of stationarity). Both methods were compared separately for stationary and nonstationary segments. An ambulatory device was used to measure the heart period data of 40 young and healthy participants during a psychological stress task and during periods of rest. Surprisingly small differences (<1%) were found between the results of both methods, with differences being slightly larger for the nonstationary segments. It is concluded that both methods perform almost identically for computation of heart period power values. Thus, the Wavelet method is only superior for analyzing heart period data when additional analyses in the time-frequency domain are required.

Many adverse effects commonly associated with chemotherapy, such as nausea, vomiting, and fatigue, are also characteristic of adrenal insufficiency. It is conceivable that chemotherapy drugs may directly or indirectly impact the activity of the hypothalamic-pituitary-adrenal axis. We examined this conjecture by characterizing temporal changes in blood cortisol concentrations in women with ovarian carcinoma given chemotherapy. Twenty-three chemotherapy-naïve women with histologically confirmed ovarian cancer underwent serial blood sampling for determination of cortisol levels prior to and every hour for 6 hr following two chemotherapy treatments with cisplatin or carboplatin. Samples were also taken for 4 hr on a comparison day when all study procedures were performed except chemotherapy administration. A significant reduction in serum cortisol was found immediately following infusion of either cisplatin or carboplatin. No progressive reduction in cortisol was found over the two treatment cycles. Because the reduction in cortisol was seen only in the presence of the cytotoxic drug, it is likely that the effect of the drug is “direct” and does not involve overt psychological or circadian mechanisms. The possible role of this reduction in cortisol is discussed in relation to induction of chemotherapy-induced nausea and vomiting.

As we continue to elucidate relationships between neural structures and cognitive functioning in this Decade of the Brain, it is important not to lose sight of the larger context. The brain is but one component of the complex system that is the body. We take in information and interact with the world through our bodies, and our bodies change with—and in some cases change—cognitive and emotional processing. In this introductory paper, we present an overview of a broad range of psychophysiological techniques: electroencephalography, event-related potentials, magnetoencephalography, positron emission tomography, optical imaging, functional magnetic resonance imaging, electromyograms, eye tracking, pupillometry, cardiovascular measures, and electrodermal activity. These techniques not only differ in their temporal and spatial resolutions but also in the physiological and psychological processes to which they are sensitive. With respect to the system as a whole, these techniques are thus complementary. Combining measures—old and new, central and peripheral—ultimately provides the most inferential power for attacking the questions we hope to answer with all psychophysiological measures in our quest to understand the nature of the relationship between the mind and the body.

Attentional modulations of event-related brain potentials (ERPs) were measured when subjects were cued to attend to a visual quadrant or to a ring-shaped region of visual space to detect infrequently presented targets within the attended region. Spatial attention directed to quadrants was reflected in modulations of sensory-evoked P1 and N1 components at lateral posterior sites and enhanced negativities (Nds) at midline electrodes that started around 150 ms poststimulus. When attention was directed to ring-shaped regions, no modulations of P1 and N1 amplitudes were found, and Nd effects observed at midline electrodes were delayed by about 50 ms. These findings indicate that behavioral effects observed both when attention is directed to contiguous regions and to general areas of visual space may be caused by different underlying processes. Intraperceptual “sensory gating” mechanisms operating in a way suggested by the notion of an attentional “zoom-lens” may be responsible for the selection of single regions, quadrants, or hemifields. When relevant regions are more complex, spatial selectivity will affect primarily postperceptual processes.