A probabilistic association task that manipulated the necessity to temporarily store information was combined with the recording of event-related potentials. In Experiment 1, scores obtained from a positive schizotypy scale were used to categorize participants as either low or high schizotypal individuals. Low, but not high, schizotypal individuals displayed evidence for selective associative learning in the working memory dependent (“trace”) version of the task. The amplitudes of the occipito-temporal N150 were attenuated in high schizotypal individuals. In Experiment 2, the intravenous administration of a single dose of haloperidol (0.04 mg/kg), but not of a placebo, strengthened the selectivity of associative learning in the trace version of the task. The amplitudes of the occipito-temporal N150 were augmented by haloperidol. Psychometrically identified schizotypal individuals and normal individuals under mild stress demonstrated defective prioritization of information in working memory and deficient visual encoding. These neurocognitive effects of schizotypy and stress seem to be mediated by the D2 family of dopamine receptors.

Disturbances in processing simple acoustic changes in a stream of stimuli have been widely reported in patients with schizophrenia, but little is know about auditory feature conjunction in these individuals. This study was designed to examine the extent to which patients with schizophrenia automatically process changes in conjunction of auditory features by using event-related brain potentials. Seventeen patients and 17 age-matched controls were presented with frequent low pitch tones at 45° to the left of center and frequent high pitch tones at 45° to the right of center while performing a continuous visual serial-choice reaction time task. The sequence of auditory stimuli included rare conjunction-deviants comprised of a different combination of features (e.g., low pitch tone at 45° right) and double-deviant tones that differed from the standard tones in both pitch and location (i.e., middle pitch at 0° azimuth). Conjunction-deviant stimuli elicited an MMN wave that was maximum at frontocentral sites. Compared with controls, the MMN to conjunction-deviant was reduced in patients and was more centrally distributed. Double-deviant sounds generated a biphasic MMN followed by a P3a wave at central sites. Both MMN and P3a were reduced in patients compared with controls. These results show that patients with schizophrenia have difficulty in automatically detecting changes in a combination of auditory features as well as orienting to what “normally” would be considered salient by healthy individuals.

This study examined the relationship between ERP components elicited by deviant stimuli by disentangling the P300 and Novelty P3 components, using spatiotemporal principal components analysis and a dense electrode array. The three-tone paradigm was used and the pitch attributes of the tones were systematically manipulated so as to map the amplitude of the ERP components on the stimulus context. A comparison was made between the components elicited by events in the three-stimulus, classical oddball, and novelty oddball paradigms. Responses to deviant stimuli consisted of independent and dissociable ERP components in the 400–600-ms time range: A parietal component (P300) that was larger for targets than rare nontargets and was affected by the difficulty of discrimination, a fronto-central component (Novelty P3) that was larger for novel tones and for rare nontargets in the difficult discrimination condition, and an additional anterior negative component responded similarly to all types of deviant stimuli.

We describe a method, based on recordings of the electroencephalogram (EEG) and eye movement potentials (electrooculogram), to track where on a screen (x, y coordinates) an individual is fixating. The method makes use of an empirically derived beam-forming filter (derived from a sequence of calibrated eye movements) to isolate eye motion from other electrophysiological and ambient electrical signals. Electrophysiological researchers may find this method a simple and inexpensive means of tracking eye movements and a useful complement to scalp recordings in studies of cognitive phenomena. The resolution is comparable to that of many commercial systems; the method can be implemented with as few as four electrodes around the eyes to complement the EEG electrodes already in use. This method may also find some specialized applications such as studying eye movements during sleep and in human–machine interfaces that make use of gaze information.

The human infant's neurophysiological responses to feeding are poorly understood. We found recently a significant increase of EEG amplitude in the newborn during nutritive feeding, but not during pacifier sucking. In this study, we report EEG responses to feeding in 13 infants at the ages of 3 and 6 months. The undifferentiated response of the newborn was found to wane until the age of 3 months, whereas in 6-month-old infants, relatively abundant rhythmic 3–5 Hz theta activity was recorded during feeding with an amplitude maximum in right posterior areas. Cessation of feeding was followed by cessation of theta activity. The rhythmic 3–5 Hz theta response to feeding is likely to represent emotional arousal, as it is similar to previous findings showing posterior theta increase in other settings connected with emotional arousal in infants.

Reduced pain perception has been observed in hypertensive individuals and normotensive individuals at risk for high blood pressure and may involve increased endogenous opioid release or receptor sensitivity. The present study examined the issue by administering two subjectively similar but physiologically different forms of the pain-reducing procedure transcutaneous electrical nerve stimulation (TENS). Men varying in resting blood pressure and parental history of hypertension participated in three testing sessions during which was presented (a) high-frequency (100 Hz) TENS; (b) low-frequency (2 Hz) TENS, the type believed to elicit endogenous opioid activity; or (c) no-TENS stimulation. Measurements of blood pressure (BP) and other physiological variables were obtained during this period. Afterwards, two pain stimuli were presented: a series of electric shocks and 5 min of arm ischemia. There was a significant negative association between pain and resting systolic blood pressure (SBP), and pain and parental history of hypertension in the no-TENS and high-frequency TENS conditions that was significantly strengthened by administration of low-frequency TENS. As well, low-frequency TENS produced a modest but significant acute reduction in SBP, especially among those with higher resting levels. These results provide further evidence that opioid mechanisms are involved in blood pressure-related hypoalgesia and blood pressure regulation.

This study examined cardiovascular effects of energy resource depletion. Participants first made a series of easy or difficult grips with their right or left hand. They then made and held a moderately difficult dynamometer grip with their right hand while measures of blood pressure and heart rate were taken. As expected, systolic blood pressure responses during the second task period were greater when the first task was difficult than when it was easy if the first task was performed with the right hand, but not if the first task was performed with the left hand. The data support the view that ability perception and, thus, cardiovascular responsiveness vary with relevant energy stores.

Physiological stress reactivity has been examined with respect to cynical hostility and anger expression, but primarily among Caucasians. Investigations of African Americans are far fewer and have focused only on the cardiovascular system. This study compared the relationships between hostility and anger expression on the one hand, and both cardiovascular and lipid reactivity on the other, among African Americans and European Americans. Forty-six men participated in a study examining cardiovascular and lipid reactivity to a speech stressor. African American men low in cynical hostility had greater blood pressure reactivity to the stressor; this effect appeared to be due primarily to low cynical men with high Anger In. Independent of ethnicity, those with a general tendency to either always express or always inhibit the expression of anger had higher triglyceride reactivity, relative to those with a more flexible style of anger expression. These results suggest that it is important to examine ethnicity in relationship to measures of hostility and anger expression, to uncover vulnerable individuals.

The ground covered by psychophysiology throughout the decades prior to its constitution as an independent discipline has not been well documented, despite its historical interest. A bibliometric study of the research published in scientific journals by 66 of the most relevant psychophysiologists from 1930 to 1964, analyzing the contents of the records indexed in the PsycINFO database, gives us an image of the state of the emergent discipline during that period. This study reveals that this was a period of consolidation, marked by the refinement of instruments and procedures, the characterization of measurements, and the establishment of the basic relationships between physiological and psychological variables, the development and validation of basic constructs such as activation, or interest in the study of psychopathology. In these years the foundations of psychophysiology were laid, leading to the formalization of the discipline at the end of the period.

Cardiovascular effects of social evaluation, evaluator status, and monetary reward were examined in participants presented with a challenge that allowed them to work as hard as they pleased (unfixed conditions) or called for a low level of effort (fixed conditions). In Experiment 1, evaluation was found to potentiate systolic pressure and heart rate responses insofar as the evaluator had status where the challenge was unfixed, but to have no impact on the responses where the challenge was fixed. In Experiment 2, reward value was found to potentiate the responses where the challenge was unfixed, but not where it was fixed. The main findings confirm and extend results from a previous experiment, and broaden the base of empirical support for the suggestion that active coping will be proportional to success importance where performance is unconstrained.

ERP researchers use differences in scalp distributions to infer differences in spatial configurations of neuroelectric generators. Since McCarthy and Wood (1985) demonstrated that a spatially fixed current source varying only in strength can yield a significant Condition × Electrode interaction in ANOVA, the recommended approach has been to normalize ERP amplitudes, for example, by vector length, prior to testing for interactions. The assumptions of this procedure are examined and it is shown via simulations that this application of vector scaling is both conceptually flawed and unsound in experimental practice. Because different spatial configurations of neural generators cannot reliably be inferred from different scalp topographies even after amplitude normalization, it is recommended that the procedure no longer be used for this purpose.

Categorization is a basic means of organizing the world around us and offers a simple way to process the mass of stimuli one perceives every day. The ability to categorize appears early in infancy, and has important ramifications for the acquisition of other cognitive capacities, but little is known of its development during childhood. We studied 48 children (7–15 years of age) and 14 adults using an animal/nonanimal visual categorization task while event-related potentials (ERPs) were recorded. Three components were measured: P1, N2, and P3. Behaviorally, the children performed the task very similarly to adults, although the children took longer to make categorization responses. Decreases in latencies (N2, P3) and amplitudes (P1, N2, P3) with age indicated that categorization processes continue to develop through childhood. P1 latency did not differ between the age groups. N2 latency, which is associated with stimulus categorization, reached adult levels at 9 years and P3 latency at 11 years of age. Age-related amplitude decreases started after the maturational changes in latencies were finished.

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.

To test the hypothesis that activation asymmetries of the most anterior parts of the prefrontal cortex may be related to state-dependent regulation of emotion, spontaneous changes of cortical activation asymmetries from one session to a second one were related to spontaneous mood changes in two large samples (ns = 56 and 128). The interval between sessions was 2 to 4 weeks. Results show that mood changes specifically covary with changes of EEG asymmetry at the frontopolar electrode positions, but not with changes at other locations (dorsolateral frontal, temporal, and parietal). Anxiety, tension, and depression were found to decrease when frontopolar activation asymmetry shifted to the right. Taking the new findings into account may contribute to the refinement and extension of theories on EEG laterality and emotion.

Abnormalities during a smooth pursuit eye movement task (SPEM) are common in schizophrenic patients and their relatives. This study assessed various components of SPEM performance in first-degree unaffected relatives of schizophrenic patients. One hundred individuals with schizophrenia, 137 unaffected first-degree relatives, and 69 normal controls completed a 16.7°/s SPEM task. Smooth pursuit gain, catch-up saccades (CUS), large anticipatory saccades, and leading saccades (LS) were identified. Groups were compared with parametric and admixture analyses. Schizophrenic patients performed more poorly than unaffected relatives and normals on gain, CUS, and LS. Unaffected relatives were more frequently impaired than normals only on gain and LS. Relatives of childhood-onset and adult-onset probands had similar impairments. Gain and frequency of leading saccades may be genetic endophenotypes in childhood-onset and adult-onset schizophrenia.

This study examined possible neuroendocrine mechanisms underlying the association between stress and antibody response to vaccination. Hepatitis B antibody titers were obtained, and salivary cortisol and cardiovascular activity measured during baseline, mental arithmetic, and recovery in 30 undergraduates. It was hypothesised that higher reactivity would be associated with poorer antibody status. Compared to individuals with high antibody titers, those with low titers had significantly lower cortisol levels throughout, exhibited a significantly attenuated end-of-task reduction in cortisol relative to resting baseline, and had larger cardiac output and inotropic reactions, but smaller increases in total peripheral resistance, to mental arithmetic. In sum, variations in indices of both hypothalamic pituitary adrenocortical axis and sympathetic nervous system activity were associated with individual differences in immune response to vaccination.

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.

The effects of auditory spatial attention on event-related brain potentials (ERPs) were examined in situations that promoted stream segregation. Short and long noise bursts were presented at three azimuth locations and listeners were asked to respond to the longer sounds occurring at either the right- or left-most location. In the baseline condition, the three sound sources were evenly spaced apart. In the distractor clustering conditions, middle and far sounds were clustered. In the attended clustering conditions, middle and attended sounds were clustered. ERP indices of attention, isolated as negative difference (Nd) waves, were greater over the hemisphere contralateral to the attended location. Nd waves were also larger when the middle sounds were moved toward the far distractors, consistent with an object-based gradient of auditory attention in which higher order information provided by the perceptual context influences selective processing.

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.

Error trials are associated with faster responses than correct trials in simple discrimination tasks suggesting that errors result from impulsive responding. We investigated the relationship between error negativity (Ne/ERN), an event-related potential associated with error detection, and two behavioral indices of response control: response time (RT) differences between incorrect and correct trials (an index of impulsivity) and percentage of errors. Response-locked ERPs were collected from 17 young adults during a visual flanker task. Consistent with previous findings, participants were significantly faster on error trials. However, participants who exhibited larger Ne/ERN peak amplitudes had significantly smaller RT differences, suggesting a more controlled response strategy. Furthermore, Ne/ERN latencies were positively associated with percentage of errors. These findings are consistent with the view that the Ne/ERN reflects the activity of a monitoring system that is closely linked to remedial systems responsible for individual differences in response control or impulsive behavior.