Thought disorder in schizophrenia may involve abnormal semantic activation or faulty working memory maintenance. Event-related potentials (ERPs) were recorded while sentences reading “THE NOUN WAS ADJECTIVE/VERB” were presented to 34 schizophrenic and 34 control subjects. Some nouns were homographs with dominant and subordinate meanings. Their sentence ending presented information crucial for interpretation (e.g., The bank was [closed, steep]). Greatest N400 activity to subordinate homograph-meaning sentence endings in schizophrenia would reflect a semantic bias to strong associates. N400 to all endings would reflect faulty verbal working memory maintenance. Schizophrenic subjects showed N400 activity to all endings, suggesting problems in contextual maintenance independent of content, but slightly greater N400 activity to subordinate endings that correlated with the severity of psychosis. Future research should help determine whether a semantic activation bias in schizophrenia toward strong associates is reflected in ERP activity or whether this effect is overshadowed by faulty verbal working memory maintenance of context.

Subjects were required to attend to a combination of stimulus modality (vision or audition) and location (left or right). Intermodal attention was measured by comparing event-related potentials (ERPs) to visual and auditory stimuli when the modality was relevant or irrelevant, while intramodal (spatial) attention was measured by comparing ERPs to visual and auditory stimuli presented at relevant and irrelevant spatial locations. Intramodal spatial attention was expressed differently in visual and auditory ERPs. When vision was relevant, spatial attention showed a contralateral enhancement of posterior N1 and P2 components and enhancement of parietal P3. When audition was relevant, spatial attention showed a biphasic fronto-central negativity, starting after around 100 ms. The same effects were also present in ERPs to stimuli that were presented in the irrelevant modality. Thus, spatial attention was not completely modality specific. Intermodal attention effects were also expressed differently in vision and audition. Taken together, the obtained ERP patterns of the present study show that stimulus attributes such as modality and location are processed differently in vision and audition.

We investigated whether verbs and nouns evoke comparable behavioral and N400 effects in a primed lexical decision task. Twenty-nine students were tested, 13 in a pilot study in which only response times and error rates were collected and 16 in a study in which ERPs were recorded from 124 scalp electrodes. Stimuli were noun–noun and verb–verb pairs with the targets bearing either a strong, a moderate, or no semantic association to the prime or being a pseudoword. Behavioral data revealed comparable priming effects for both word categories. These proved to be independent from the SOA (250 and 800 ms) and they followed the well-known pattern of decreasing response times and error rates with increasing relatedness between target and prime. ERPs revealed pronounced N400 effects for both word categories with a larger amplitude for noun than for verb pairs. A systematic analysis of topographic differences between noun- and verb-evoked ERPs and N400 effects, respectively, gave no convincing support to the hypothesis that the two word categories activate distinct neuronal networks.

A group of 32 healthy adult volunteers completed three blocks of a reaction time task that varied in the degree of controlled processing load. A rest period preceded each of the task blocks. The task blocks were presented in the order of either increasing or decreasing cognitive load. For each of the six periods, mean values and spectral measures of heart rate and respiration variability were calculated. The spectral measures were obtained for three different frequency bands. Differences between the cardiac measures of the task and preceding rest periods were compared with respect to differences in task load and the order of task presentation. All comparisons were carried out while adjusting for respiratory variability in the corresponding frequency band. The frequency band in which task load-related changes in heart rate variability became manifest appeared to be dependent on the individual's breathing pattern.

In this study we compared the amplitude, latency, and spatial distribution of the mismatch negativity (MMN), elicited by tones deviating in either frequency, intensity, stimulus-onset asynchrony (SOA) or location, and assessed inter- and intra-subject variability. Cross-dimensional comparisons were facilitated by adjusting the magnitude of deviance individually, so that the detection rates were similar, both across dimensions (within subject) and across subjects (within dimension). Despite similar detection rates, the MMN elicited by frequency deviance was larger, and the MMN elicited by SOA deviance was earlier than the other types of MMN. The reliability of frequency-related MMN was better than that of the other types of MMN. The results highlight the problems of comparing MMN across dimensions, especially in clinical populations.

The present study examined the effect of self-focused attention on the startle reflex and heart rate and assessed the assumption that socially anxious individuals become self-focused in evaluative situations. Twenty-five high and 30 low socially anxious men performed a digit recall task under evaluative or nonevaluative instructions. Half of the trials were performed under self-focused conditions and half under non-self-focused conditions. Self-focus led to larger startle responses among socially anxious individuals and had no effect on heart rate. Self-focus combined with evaluation led to poorer recall performance among all subjects. Results provide evidence against a directional change in attention during self-focused attention and favor the view that self-focus increases access to self-relevant thought content and decreases available processing resources.

Ambulatory blood pressure monitoring was used to investigate the cardiovascular correlates of naturally occurring interpersonal interactions. Participants were New York City traffic agents, who routinely engage in conflict-prone communication with the public under relatively fixed conditions. Talking with the public, supervisors, or coworkers was associated with levels of systolic and diastolic blood pressure and heart rate that exceeded a resting baseline. Blood pressure was higher when agents were talking to the public than when they were talking to coworkers or engaged in a noncommunicative work task. Systolic blood pressure response during communication was associated with the agent's mood. Blood pressure effects associated with communication appear to persist after the communication has ceased. Implications of these data for the reactivity hypothesis of the pathogenesis of cardiovascular disease are discussed.

The partial pressure of carbon dioxide in the arterial blood (PaCO2) is usually tightly regulated, yet it varies among healthy people at rest (range ∼32–44 mmHg) as well as within an individual during many natural life situations. The present study examined whether modest changes in end-tidal PCO2 (PetCO2; a noninvasive measure of PaCO2) affect electroencephalographic (EEG) activity, cognitive function, and vigilance. Nine adults were ventilated mechanically using a mouthpiece; respiratory rate and breath size were held constant while PetCO2 was set to levels that produced minimal discomfort. Despite discrete changes in EEG, neither acute PetCO2 increases (mean = 47 mmHg) nor decreases (mean = 30 mmHg) from resting levels (mean = 38 mmHg) affected performance on cognitive tasks, latency or amplitude of the N1, P2, or P3 event-related potential, or alertness. Modest changes in PetCO2 may cause significant alterations in the EEG without disturbing cognitive function.

Psychological accounts of hypnosis have hypothesized that hypnosis and attention might share similar mechanisms and that hypnosis simply represents an extensive state of reduced attention. This assumption implies that reports of pain and electrocortical brain responses to painful stimulation should be similarly reduced when subjects are exposed to suggestions of hypnotic analgesia (HA) or requested to distract their attention from painful stimuli (distraction of attention: DA) as compared to a control condition (CC). To test this hypothesis, we recorded event-related electrical brain potentials to noxious laser-heat stimuli and pain reports during HA, DA, and CC from subjects highly susceptible to hypnotic suggestions. Pain reports were significantly reduced during HA and DA as compared to CC. The amplitudes of the late laser-evoked brain potential (LEP) components N200 and P320 were also significantly smaller during DA than during CC. However, no significant difference of these late LEP amplitudes was obtained for HA as compared to CC. Results indicate that hypnotic analgesia and distraction of attention represent different mechanisms of pain control and involve different brain mechanisms.

We examined heritability of error rate on the antisaccade task among female twin youths. This task appears to be sensitive to prefrontal functioning, providing a measure of individual differences in inhibitory control associated with genetic risk for schizophrenia. The sample consisted of 674 11-year-olds and 616 17-year-olds, comprising the two cohorts of female twins from the Minnesota Twin Family Study, a population-based investigation of substance abuse and related psychopathology. We used biometric model-fitting methods to determine the relative magnitude of genetic and environmental influences on performance. In both age cohorts, the best fitting model contained additive genes and nonshared environment. Despite substantial age-related differences in mean performance levels (effect size = .81), additive genes accounted for greater than half the variance in performance in both age cohorts. These results are consistent with the hypothesis that antisaccade error rate might serve as an endophenotype for behavior disorders reflecting frontal lobe dysfunction or problems with inhibitory control.

Two experiments assessed the preparatory effects of advance information about response force and movement direction on the lateralized readiness potential (LRP). In a choice reaction time (RT) task, an imperative stimulus required an isometric flexion or an extension of the left or right index finger. Prior information about response force or about movement direction reduced RT and shortened the interval from the onset of the imperative stimulus up to the onset of the LRP. Advance information, however, about direction but not about force decreased the interval from LRP onset to the onset of the overt response. The identical pattern of results was obtained in a second experiment, in which each participant performed both precue conditions. The findings of both experiments support the notion that response force is specified before movement direction. These results are consistent with the view accordingly different mechanisms are involved in the specification of muscle force and movement direction.

The role of the autonomic nervous system in secretory immunoglobulin A (sIgA) responses to laboratory challenge was explored in a study in which sIgA and cardiovascular activity were recorded at rest and during mental arithmetic and paced breathing. These tasks were selected to preferentially engage the sympathetic and parasympathetic nervous systems, respectively. Mental arithmetic elicited a mixed pattern of increased alpha- and beta-adrenergic activity and a reduction in parasympathetic activity; diastolic blood pressure, total peripheral resistance, and systolic blood pressure increased, preejection period shortened, and heart rate variability decreased. In contrast, paced breathing primarily elicited an increase in parasympathetic activity; heart rate variability increased. Mental arithmetic also provoked an increase in sIgA concentration but no change in saliva volume, whereas paced breathing affected neither sIgA concentration nor saliva volume. These data suggest that sIgA responses to laboratory challenges are mediated by sympathetic rather than parasympathetic processes.

The present study investigated psychophysiological responses to paced respiration of different frequencies. Twenty men and 20 women (mean age: 24.3 years) underwent five breathing conditions (paced with 0.15 Hz, 0.20 Hz, 0.25 Hz, 0.30 Hz, and unpaced), each lasting 5 min. As dependent physiological measures heart period, and different heart period variability (HPV) parameters were assessed. Psychological variables consisted of mood estimates as well as rated accuracy and effort to follow the pacing rhythm. HPV decreased with higher breathing frequencies, under paced and unpaced conditions, whereas mood ratings did not change. Subjects indicated more effort and less accuracy in following the pacing signal, the more its frequency differed from their spontaneous breathing frequency. The comparison of a spontaneous breathing condition with a frequency-matched paced condition revealed that pacing per se provoked a reduction in heart period. Because this decrease was not accompanied by changes in any of the HPV frequency components, their validity as measures of autonomic control needs to be questioned.

Contextual fear conditioning was examined using the startle reflex in two groups of participants over two sessions separated by 1/2 h. The conditioned stimulus (CS) was paired (paired group) or not (unpaired group) with an unpleasant shock during conditioning. The paired group showed conditioning to the CS that was well retained over the retention interval. Session 1 intertrial interval startles—a measure of contextual conditioning—were greater in the unpaired compared to the paired group. Context conditioning was retained in Session 2 and was present before the shock electrodes were attached. Self-rating of state anxiety, arousal, and pleasure indicated differential changes in mood from Session 1 to Session 2 in the two groups, with the unpaired group showing relatively greater negative affects compared to the paired group. These results indicate that unpredictable shocks lead to greater context conditioning as measured by startle and self-reports.

Episodic memory encoding and distinctiveness detection were examined using event-related potentials (ERP) in a single-trial word list learning paradigm with free recall following distraction. To manipulate distinctiveness, encoding of high- and very low-frequency words was contrasted. Amplitudes of the N400 and late positive component (LPC) were larger for low- than for high-frequency words, and ERPs were more positive for subsequently recalled than not recalled words. This subsequent memory effect was dissociated from the correlates of distinctiveness by polarity for the N400 and by time course for the LPC and dissociable into two effects. The data suggest that the first subsequent memory effect, which occurred for both word categories, is more directly related to episodic memory formation, whereas the second effect, which occurred for high-frequency words only, is related to processes influencing episodic encoding success indirectly.

Acute stress elevates blood lipids, with the largest increases among men and postmenopausal women. The mechanisms for the effect are unknown, but may be due to altered lipid metabolism. This study investigated if acute stress induces transient reductions in triglyceride clearance in middle-aged men and women, and determined if gender and menopause affect triglyceride metabolism. Of the 35 women, half were premenopausal, and half were naturally postmenopausal; men (n = 35) were age matched. Clearance of an intravenously administered fat emulsion was assessed twice: once during a nonstress session, and again during a stress-testing session. During the stress session, a battery of behavioral stressors (serial subtraction, speech, mirror tracing, and Stroop) were performed for 40 min. The clearance rate of exogenous fat was significantly diminished during the stress, relative to the nonstress session. Women had more efficient clearance, relative to men, but there were no effects of menopausal status. The diminished ability to clear an intravenous fat emulsion during stress suggests one mechanism for stress-induced elevations in lipids.

Event-related potentials were recorded to investigate the mechanisms of hierarchical processing and level-repetition effect. Participants identified targets that appeared at global, local, or both levels of hierarchical patterns. Reaction times showed global precedence and level-repetition effects. An occipital P1 wave was enhanced to local relative to global targets. The P1 to local targets was also larger when preceded by global than local targets. Global and both-level target selections were indexed by two posterior negativities peaking at 130 and 190 ms poststimulus, whereas local target selection was indexed by a broad occipitotemporal negativity. A late selection positivity was observed over the left occipitotemporal site for global targets but over the central site for local targets. The findings suggest that sensory-perceptual mechanisms contribute to global precedence and level-repetition effects in hierarchical processing.

Although Unibase cream has been an effective medium for electrodermal recordings, its production has recently been discontinued. This study compared alternative media to Unibase for effectiveness. Three base creams similar to Unibase were initially compared for in vitro viscosity and effectiveness. Based upon this analysis one cream was eliminated. A volunteer sample of 6 postmenopausal women with hot flashes and 6 young women without flashes was recruited. Media were evaluated for viscosity and effectiveness of skin conductance. Results indicated that one electrolyte media produced readings within the normal range, identified true positive hot flashes, and produced few false negative readings whereas the second produced largely unreadable results with many false negative hot flashes. An appropriate substitute for Unibase as an effective electrolyte medium for measurement of electrodermal activity was identified.

We studied the modulation of oscillatory resistance (Ros) by viewing and imagery of affective pictures. Thirty nonasthmatic participants viewed 36 affective slides precategorized as positive, neutral, and negative in valence. Each picture was presented for 15 s, followed by an imagery epoch of 15 s. Ros, facial EMGs, respiration, skin conductance response, heart period, and respiratory sinus arrhythmia were measured throughout the session, as well as viewing time and ratings of pleasure, arousal, and interest. Increases of Ros were observed for negative pictures, and little changes for positive or neutral pictures. Other physiological parameters did not mirror this response pattern, leaving no clear indication for a ventilatory or vagal origin of Ros changes. Overall differences between behavioral contexts of visual processing and imagery revealed evidence for a coupling of cardiac and respiratory responses, which included changes in Ros. The findings in Ros are discussed in the light of earlier discrepant findings on the affective modulation of airway resistance and cardiac activity.

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.