Test–retest stability of electrodermal (EDA) variables indexing both general autonomic arousal (e.g., skin conductance level, number of nonspecific skin conductance responses) and attention to external stimuli (e.g., number of skin conductance orienting responses, electrodermal responder/nonresponder status) was assessed in 71 young, recent-onset schizophrenia patients and 36 demographically matched normal subjects. Significant stability over a 1-year period was found for both patients and normal subjects for most EDA variables and for responder/nonresponder status, with test–retest correlations generally being higher for normal subjects. The lower reliability for patients was not attributable to symptomatic fluctuations during the follow-up period and may reflect poorer arousal regulation among the patients. Among measures of responding to nontask stimuli, a simple count of the number of orienting responses occurring was more stable than was a traditional trials-to-habituation measure.

Event-related potentials (ERPs) and behavioral responsiveness were investigated during the transition from wakefulness to sleep. Ten participants were presented with an auditory oddball task during repeated sleep onset periods. The EEG was recorded from 29 different scalp sites. A 1500-Hz tone pip was presented infrequently (p = .04) within a series of lower pitch 1000-Hz “standard” stimuli (p = .96). Participants were required to button press upon detection of the rare “target” stimulus. During wakefulness, almost all targets were detected. A large amplitude P300 was observed to these detected targets. This P300 was maximum over parietal areas of the scalp. During stage 1 sleep, subjects continued to respond on 47% of trials. The parietal P300 amplitude remained large to these detected targets. It was, however, much attenuated at frontal sites. When the participant failed to detect the target in either stage 1 or 2, no P300 was visible. P300 is thus associated with behavioral detection of the target stimulus, whether in wakefulness or stage 1 “sleep.” Trials were also sorted by reaction time (RT), in which bins 1–3 represented increasingly long RT. In the waking state, P300 amplitude did not significantly vary across the different bins. Although mean RT latency varied by 512 ms from bin 1 to bin 3, P300 latency varied by only 25 ms. Differences in RT are thus probably due to response-related processes rather than stimulus classification time.

Electrooculogram (EOG) correction is used to remove eye-movement-related contamination from electroencephalograms (EEG). Correction is reliant on the regression procedure, although when multiple EOG channels are used in the correction, the appropriate type of regression to use is not known. In the present study, we aimed to resolve this matter. Computer simulations were used to compare the simultaneous, multiple-stage, and single-channel regression methods of correction. EOG propagation was modeled on prior findings, under conditions of varying vertical and horizontal EOG (VEOG/HEOG) correlation. The dependent variable was the correlation between the uncontaminated and the corrected EEG. The simultaneous regression procedure gave the best correction, with its advantage increasing as a function of VEOG/HEOG correlation. It is recommended that the simultaneous regression procedure be used for EOG correction of the EEG.

The temporal and hierarchical relationships between the dorsal and the ventral streams in selective attention are known only in relation to the use of spatial location as the attentional cue mediated by the dorsal stream. To improve this state of affairs, event-related brain potentials were recorded while subjects attended simultaneously to motion direction (mediated by the dorsal stream) and to a property mediated by the ventral stream (color or shape). At about the same time, a selection positivity (SP) started for attention mediated by both streams. However, the SP for color and shape peaked about 60 ms later than motion SP. Subsequently, a selection negativity (SN) followed by a late positive component (LPC) were found simultaneously for attention mediated by both streams. A hierarchical relationship between the two streams was not observed, but neither SN nor LPC for one property was completely insensitive to the values of the other property.

Perpetrators of domestic violence describe symptoms that are compatible with exaggerated autonomic arousal at the time of the domestic violence. This inappropriate arousal may be reflected in altered heart rate regulation. If heart rate is systematically regulated by vagal mechanisms, then increases in heart rate should correlate with decreases in cardiac vagal activity, as indexed by respiratory sinus arrhythmia (RSA). We hypothesized that perpetrators of domestic violence have an alteration in heart rate regulation. To test this hypothesis we compared the results of a postural shift performed on perpetrators, healthy volunteers, and nonviolent alcoholics. Results showed there were no significant differences in heart rate, RSA, or catecholamines. However, the significant inverse relationship between posture-elicited changes in RSA and heart rate present in the healthy volunteers was not found in perpetrators. These differences in the covariation between heart rate and RSA may represent differences in the neural regulation of heart rate and may be related to difficulties in controlling autonomic state.

In two previous experiments, we studied how stimulus motion affects both the self-report of emotion experience and the physiological sequelae of emotion. In both studies, image motion intensified emotional responding, and the effect of motion was relatively specific to the arousal dimension of the emotion; there was little evidence that image motion altered the valence of the image. Moving images also appeared to sustain the attention of the participants for a longer period of time than did the still images. In these two experiments, however, image motion was manipulated within participants. In the present experiment, we used a between-subjects manipulation of image motion and found a nearly identical pattern of results. These data indicate that motion inherently increments the arousal value of an image and that this increment is not dependent on the context in which motion is introduced.

Alterations in a number of measures of cardiac activity were examined during sleep onset in 6 participants over 3 experimental nights. Each sleep onset was divided into four consecutive phases: wakefulness, mixed alpha and theta activity, stage 2 NREM sleep with arousals, and stable stage 2 sleep. The variables measured were heart rate (HR), respiratory sinus arrhythmia (RSA), pre-ejection period (PEP) and T-wave amplitude (TWA). Respiration rate (RR) was also measured. HR and RR were lower in stable Stage 2 sleep compared with wakefulness, whereas PEP, TWA and RSA did not change significantly. During the second and third phases of sleep onset, HR decreased at each transition into sleep and increased following each spontaneous arousal. This increase resolved rapidly, with a return to sleep levels by 12 beats after the arousal. HR changes are discussed with reference to RSA, PEP, TWA and the concept of a waking reflex.

We tested the hypothesis that blood pressure (BP) responses to physical and mental stress are associated with polymorphisms in the β-2 adrenergic receptor (AR) gene. We studied normotensive, young, monozygotic (MZ) and dizygotic (DZ) twins. The subjects underwent automated BP measurements at the brachial and digital arteries and were subjected to mental arithmetic and cold pressor stress. We used allele-specific PCR to genotype four single nucleotide polymorphisms in the β-2 AR gene. The most functionally relevant polymorphism in the β-2 AR gene, Arg16/Gly, was associated with systolic and diastolic BP under resting conditions, during mental arithmetic, and during the cold pressor test, as well as with the increase in diastolic BP during both forms of stress. These findings support a role for the β-2 AR gene in BP regulation. They also indicate that the β-2 AR gene influences the level of not only resting but also stress-related BP.

Schizophrenia patients and their relatives have saccadic abnormalities characterized by problems inhibiting a response. The dorsolateral prefrontal cortex and its associated circuitry ostensibly mediate inhibition and support correct delayed response performance. In this context, two components of delayed response task performance are of interest: memory saccade metrics and error saccades made during the delay. To evaluate these variables, an ocular motor delayed response task was presented to 23 schizophrenia patients, 25 of their first-degree biological relatives, and 19 normal subjects. The measure that best differentiated groups was an increased frequency of error saccades generated during the delay by schizophrenia subjects and relatives. Decreased memory saccade gain also characterized patients and relatives. The similar pattern of results demonstrated by the patients with schizophrenia and their relatives suggests that performance on ocular motor delayed response tasks, either alone or in combination with other saccadic variables, may provide useful information about neural substrates associated with a liability for developing schizophrenia.

Previous research has suggested that the stimulus-preceding negativity (SPN) is largely independent of stimulus modality. In contrast, the scalp topography of the event-related desynchronization (ERD) related to the anticipation of stimuli providing knowledge of results (KR) is modality dependent. These findings, combined with functional SPN research, lead to the hypothesis that anticipatory ERD reflects anticipatory attention, whereas the SPN mainly depends on the affective-motivational properties of the anticipated stimulus. To further investigate the prestimulus ERD, and compare this measure with the SPN, 12 participants performed a time-estimation task, and were informed about the quality of their time estimation by an auditory or a visual stimulus providing KR. The KR stimuli could be either intact or degraded.

Auditory degraded KR stimuli were less effective than other KR stimuli in guiding subsequent behavior, and were preceded by a larger SPN. There were no effects of degradation on the SPN in the visual modality. Preceding auditory KR stimuli no ERD was present, whereas preceding visual stimuli an occipital ERD was found. However, contrary to expectation, the latter was larger preceding intact than preceding degraded stimuli. It is concluded that the data largely agree with an interpretation of the pre-KR SPN as a reflection of the anticipation of the affective-motivational value of KR stimuli, and of the prestimulus ERD as a perceptual anticipatory attention process.

The aim of the present study was to investigate the modulations in amplitude of H reflexes elicited in a hand muscle, the flexor pollicis brevis, during the performance of a choice reaction time (RT) task in which this muscle was directly involved. Ten subjects were to choose between a left- or a right-thumb key-press according to the lateral location of a flash of light. The stimulus–response mapping was either compatible or incompatible. Hoffman reflexes were elicited at different times during the RT by stimulation of the median nerve. Twenty-five milliseconds before the voluntary response, the amplitude of the H reflex suddenly increased when the muscle was involved in the response and decreased symmetrically when the muscle was not involved in the response. Mapping compatibility exerted no detectable influence on the changes in spinal excitability. The latter result supports the assumptions that are at the core of Sternberg's additive factor method.

In a repetitive auditory stimulus sequence, deviant infrequent tones typically elicit a component of auditory event-related potentials termed mismatch negativity (MMN). The elicitation of MMN is assumed to reflect the existence of a memory trace of the standard stimulus that has a decay time of about 10 s and is strengthened by repetition of the standards. The main aim of the present study was to test the decay time of the sensory memory trace during rapid-eye movement (REM) sleep vs. wakefulness, as indexed by the MMN. Subjects were presented 10 tone trains, separated by 3, 6, or 9 s of silence, during waking and REM sleep. Each train consisted of 9 standards of 1000 Hz and 1 deviant of 2000 Hz that occurred at position 1, 2, 4, or 6. The waking deviants elicited a frontocentral negativity with a scalp topography equivalent to the MMN component. During REM sleep, the negative component showed the same scalp distribution only for the 3-s intertrain interval (ITI). In this brain state, the MMN amplitude was smaller and decreased with prolongation of the ITI. These results suggest a weaker sensory memory trace formation and a premature decay time of such a memory trace during REM sleep as compared with wakefulness.

Previous studies have suggested that the memory underlying the mismatch negativity (MMN) can be deactivated by a period of silence and later reactivated. An alternative is that the memory becomes inapplicable due to a period of silence and subsequently reinstated. Both interpretations rest on the absence of a MMN for a deviant in Position 1 of a train (showing deactivation or inapplicability of the memory) and the presence of a MMN in Position 2 of the train (evidencing reactivation or reinstatement of the memory). In these studies, the standards were fixed across all trains of a given condition. Hence, it is not clear if the MMN elicited in Position 2 requires presentation of multiple trains with identical standards or only a single train. Experiment 1 showed that a single train is sufficient. With data from recent studies, Experiment 2 showed that MMNs in Position 2 of trains are due to reinstatement rather than reactivation of the memory.

Attentional and information processing impairments have been evidenced in nonclinical anhedonic subjects. However, the extent of attentional deficit has not been determined. We studied focused attention, the ability to reject irrelevant or distracting messages, in anhedonic nonclinical subjects. The event-related potentials and behavioral performances of anhedonic subjects were compared with those of control subjects during the Eriksen focused attention task (C.W. Eriksen & B.A. Eriksen, 1974); the task combined one compatible and one incompatible condition, the latter causing an interference. Anhedonic subjects exhibited a smaller P300 and slower reaction times than control subjects. Varying task conditions had different effects on anhedonic subjects and controls, suggesting that anhedonic subjects may have developed a conservative response strategy. In view of previous works, these results suggest that attentional impairment is not ascribed to specific processes, but may involve a more global deficit, that is, a resource allocation deficit.

Evidence from both hypertensive and normotensive individuals indicate that elevated blood pressure is associated with decreased pain sensitivity. The current study sought to experimentally raise blood pressure using 250 mg caffeine, and investigate its effects on the cold pressor pain experiences of 25 men and 25 women. In a placebo-controlled repeated-measures experiment, caffeine increased systolic and diastolic blood pressure, as well as producing more clearheaded and energetic feelings. Caffeine produced higher pain threshold and pain tolerance levels compared to placebo, and women had a lower tolerance to pain than men. Finally, a significant association was found between caffeine-related increase in systolic blood pressure and caffeine-related increase in pain tolerance. Furthermore, this association was the strongest in women. These results are discussed in light of future directions for pain and hypertension research.

The pathogenic processes responsible for cardiovascular disease have their origins in childhood. Although children's measures of heart rate and blood pressure have been found to be reliable, the reliability of impedance cardiography derived measures have not been evaluated. Thirty-three children, ages 8–11 participated in two sessions. Stressors included serial subtraction, isometric handgrip, and mirror-image tracing. Results indicated the impedance measures showed moderately high temporal stability (average scores ravg = .74; difference scores ravg = .53) and intertask consistency (average scores ravg = .78; difference scores ravg = .53). Blood pressure demonstrated the lowest reliability; Heather index, preejection period, and stroke volume demonstrated the highest. These findings suggest children's cardiovascular reactivity to laboratory stressors can be reliably and consistently assessed using impedance cardiography.

We examined hemodynamic and autonomic components of blood pressure responses during active and passive stressor tasks in a sample of young, normotensive men and women who were physically active but differed on fitness (i.e., [V below dot]O2peak). During the hand cold pressor, increases in systolic blood pressure were inversely related to fitness among women but not men. Regardless of gender, fitter participants had a greater increase in cardiac pace during mental arithmetic, coherent with a decreased cardiac-vagal component of heart rate variability, and a greater compensatory reduction in stroke volume. Fitness was otherwise unrelated to changes in cardiac output and vascular resistance during the stressor tasks. Our findings suggest that cardiorespiratory fitness augments the cardiac-vagal withdrawal that is characteristic of mental arithmetic. The blunted systolic blood pressure response to the hand cold pressor among fitter women suggests that cardiorespiratory fitness should be considered as a covariate in studies that examine the hand cold pressor as a predictor of future hypertension among women.

We examined changes of event-related potentials (ERPs) while participants learned stimulus-to-stimulus relations in an S1-S2 task. The design allowed for separating processes of associative learning from nonspecific effects. Participants had to respond to S2 by a left or right key-press dependent on S2 identity (letter W or M). Preparation for S2 could be improved by using the associative information given by S1. The S1 was an arrow pointing to the left or right. In combination with its color, arrow direction was informative about location and identity of S2, but participants were not informed about the relevance of color. Arrows in two of the colors were fully predictive for the S2 whereas the third color gave no valid information. This third stimulus controlled for habituation and procedural learning. Six blocks with 200 trials each and all three S1 colors in random order were presented. Behavioral and ERP differences in each block between “learning” and control trials were used to identify processes of associative learning. Several effects of associative learning were identified indicating the involvement of specific stages of information processing: a continuous increase of P3 amplitude evoked by S1 was accompanied by a decrease of P3 evoked by S2. These changes reflected the modifications of stimulus weights for response selection and the strengthened association between the two stimulus complexes in the time course of learning. The related motor preparation benefited from learning too, expressed in a decrease of CNV amplitude and an increase of LRP amplitude. Finally a decrease of N1 amplitude evoked by S2 indicated the reduced need to allocate spatial attention to the S2 location according to the learned meaning of S1.

Memory-driven processing in medial occipital areas (Area V1 and immediately adjacent structures) was investigated noninvasively using the event-related optical signal (EROS). Subjects viewed two letter stimuli presented in the left and right hemifields, respectively. They then viewed a centrally presented test letter and had to indicate whether this letter was the same as either of the letters presented earlier. The initial EROS response to the test stimulus in medial occipital areas (latency: 50–150 ms) was unilaterally suppressed in the hemisphere previously exposed to the same stimulus. This finding suggests that medial occipital cortex activity is modulated by a rapidly adapting hemispheric-specific pattern recognition mechanism.

This study aimed to identify different processes in working memory, using event-related potentials (ERPs) and response times. Abstract polygons were presented for memorization and subsequent recall in a delayed matching-to-sample paradigm. Two polygons were presented bilaterally for memorization and a cue indicated whether one (and if so, which one of the two) or both polygons had to be memorized. A subsequent test figure was presented unilaterally to the left or right visual field and had to be compared with the memorized figure(s). ERP results suggested that memorization takes place in a visual buffer in contralateral posterior brain areas, whereas identification of the test stimulus as a target appears to be mainly a left hemispheric process. Increased response times were found for nontarget test stimuli as compared to targets, and for target test stimuli that were presented contralaterally with respect to the location of the memorized stimulus. In addition, response times were slower when two figures were memorized than when only one was memorized.