Showing papers in "Psychophysiology in 1982"

Facial Reactions to Facial Expressions

Abstract: Previous research has demonstrated that different patterns of facial muscle activity are correlated with different emotional states. In the present study subjects were exposed to pictures of happy and angry facial expressions, in response to which their facial electromyographic (EMG) activities, heart rate (HR), and palmar skin conductance responses (SCRs) were recorded. It was found that happy and angry faces evoked different facial EMG response patterns, with increased zygomatic region activity to happy stimuli and increased corrugator region activity to angry stimuli. Furthermore, both happy and angry faces evoked HR decelerations and similar SCR magnitudes. The results are interpreted as suggesting that facial EMG recordings provide a method for distinguishing between response patterns to “positive” and “negative” emotional visual stimuli.

Changes in Spatial Patterns of Rabbit Olfactory EEG with Conditioning to Odors

Abstract: Electrode arrays (8 × 8, 3.5 × 3.5 mm) were implanted epidurally on the olfactory bulbs of rabbits for EEG recording. The rabbits were trained to give a conditioned response to a warning odor paired with an electric shock. EEGs were recorded and edited, and representative ERG bursts with odor and preceding the odor were selected for measurement. Each burst was displayed in a contour map of amplitude. The contour maps revealed active EEG foci in the bulb with size, shape and location unique to each rabbit. Changes in shape and location took place only during familiarization and during training, when a warning odor was paired with the aversive stimulus. The EEG spatial patterns did not change when visual or auditory stimuli were used as CS. EEG spatial patterns did not reflect conformal mapping of odor stimulus to neural activity response, but were determined by state variables of the animal related to olfactory conditioning history. The implications for human EEG are briefly discussed.

Research with twins: The concept of emergenesis.

Abstract: Preliminaty findings from an on-going study of monozygotic twins reared apart (MZA) and data from a larger sample of twins reared together (MZT and DZT), indicate a surprisingly strong influence of genetic variation on aptitudes, psychophysiological characteristics, personality traits and even dimensions of attitude and interest. For some of these variables, MZT and MZA twins show high intra-class correlations while DZT twins are no more similar than pairs of unrelated persons. It is suggested that such traits are “emergenic,” i.e., that they are determined by the interaction--rather than the sum--of genetic influences. Emergenic traits, although perhaps strongly genetic, will not tend to run in families and for this reason have been neglected by students of behavior genetics. For this and several other listed reasons, wider use of twins in psychological research is strongly recommended.

Habituation of the Blink Reflex in Normals and Schizophrenic Patients

Abstract: The present study demonstrates an impairment of habituation in schizophrenic patients on a measure of defensive responding to startling stimuli. The blink reflex component of human startle in response to 116dB(A) tones (40 msec, 1000 Hz) was monitored and distinguished from voluntary eyeblinks by a computer. With a background noise level of 70dB(A), 121 tones were given at varied intervals averaging 15 sec. All three groups tested, 25 presumed normals, 20 psychiatric patient controls and 22 schizophrenic patients, exhibited similar responses to the first several stimuli. However, while normals and patient controls exhibited roughly 70% decrements in response amplitudes across trials, schizophrenic patients habituated by less than 50%. An unexpected finding was that the latency-to-peak values for normals and controls were non-monotonically related to both trial number and response amplitudes. That is, latencies first increased and then decreased as the same stimulus was repeated. As with amplitude habituation, this phenomenon was also delayed in the schizophrenic patients. The results indicate that schizophrenic patients have abnormal habituation of defensive responses to exteroceptive stimuli. Possible links between abnormal habituation and symptom formation in schizophrenia are discussed.

Correction of EOG artifacts in event-related potentials of the EEG: aspects of reliability and validity.

Abstract: Correction of EOG artifacts using a regression approach is evaluated in terms of reliability and validity. Transmission rates are estimated for eight EEG channels in 67 subjects. The trimmed group means of these rates are shown to provide reliable measures. Eye artifact correction based on these group means is superior to the conventional rejection in terms of reducing correlation between EOG and EEG.

Electroencephalograms in children of alcoholic fathers.

Abstract: The present study tested the hypothesis that 12-yr-old sons of alcoholic fathers will evidence an excess of fast EEG activity. Such sons have been shown to be at high risk for alcoholism. In this study, EEGs were recorded on a sample of 265 subjects who had been selected to maximize risk for deviant behavior (children of schizophrenics and children of psychopathic or character disordered parents) or selected as controls (children of normal parents). The sample included 27 children of alcoholic fathers and 258 children of non-alcoholic parents. The hypothesis was confirmed, suggesting that the biological risk for alcoholism in sons of alcoholics may relate to biological factors predisposing to alcoholism.

Phasic not tonic pupillary responses vary with auditory vigilance performance.

Abstract: Pupillary movements were monitored as 11 university students listened to a series of 1K Hz 50-msec tone bursts presented at 3.2-sec intervals for a period of 48 min. Their task was to report target tones (-3dB), which were presented randomly with a probability of 0.12. Under these conditions, monitoring performance deteriorated as a function of time on the task. This vigilance decrement was attributed to both a decrease in listener sensitivity and a conservative shift in decision criterion, as determined by a signal detection analysis. The amplitude of the phasic task-evoked pupillary response reflected these changes in performance, decreasing significantly over time on the task. Tonic or baseline pupillary diameter exhibited no such relationship with performance. These results are interpreted in the context of an activation theory of attention that suggests that a common neurophysiological system mediates both intensive and sustained attentional processes.

The heart beats to reward: the effect of monetary incentive on heart rate.

Abstract: Two experiments are reported which test the hypothesis that heart rate increases will be seen in response to monetary incentives during performance on a continuous motor task. In the first study, heart rate was significantly higher when subjects were paid 2o for each success feedback compared to subjects who received feedback only. In contrast, there was no effect of varying the probability of success (10% versus 90% success). Study 2 replicated the monetary incentive effect on heart rate, this time employing 100% success feedback. In neither study were subjects' response rates significantly affected by monetary incentive. In addition, control groups responding much faster on the task as a result of making it more predictable did not show increased heart rate. Consequently, these incentive effects are difficult to explain with a cardiac-somatic coupling interpretation. It was concluded that cardiac acceleration does occur in response to monetary incentives, even in the absence of failure feedback, and it was proposed that this incentive effect reflects the activation of an appetitive motivational system. Possible applications of the assessment of appetitive responses are suggested.

Sequential expectancies and decision making in a changing environment: an electrophysiological approach.

Abstract: This experiment addressed two questions. First, we sought to determine how sequential expectancies, as indexed by the amplitude of P300, are formulated when subjects are presented with a series in which the event probabilities are continuously changing. Second, we wanted to determine the effect on P300 amplitude of seeking information prior to a decision when the decisions are required at random intervals. Eight subjects were presented with a Bernoulli series of high and low tones in which the event probabilities reversed at random intervals. Thus, while the event probabilities were either .33 or .67 over short segments of the series, they were .50 over each trial block. The subject's task was to count the number of low-pitched tones. In two separate conditions (“Unknown” and “Known”) the subjects received different information about the series. In the Unknown condition, the subjects were not informed of the reversals in stimulus probability and were only told that the events were equally probable. In the Known condition, the subjects were informed of the probability reversals and, in addition to the counting task, were asked to detect the probability reversals. The trials were divided into two categories: “transition” and “stable.” The transition trials were those that occurred between the actual probability reversal and the subject's reported detections. The stable trials were all those not included in the transition category. The data from the stable trials revealed that, in most cases, subjects generated their expectancies, as indexed by the amplitude of P300, in an identical manner during both conditions. Accurate knowledge of the stimulus probabilities did, however, influence the amplitude of P300 for events that were preceded by sequences of stimuli that occur only rarely at each level of probability. These data suggest that the mechanism responsible for generating sequential expectancies is largely automatic. Certain aspects of this mechanism are, however, modulated by the subject's knowledge of the parameters of the series. The data from the transition trials revealed that, in the Unknown condition, the subjects’ assignments of subjective probabilities, as indexed by the amplitude of P300, adapted rapidly to meet the new sequence-generating rules following the probability transitions. In contrast, during the Known condition, the amplitude of the P300 and Slow Wave components steadily increased, as the decision point approached, to levels well above those in the Unknown condition. By the first trial following the decision, this enhancement in P300 and Slow Wave activity was no longer evident. These results are discussed in terms of a descriptive model of the subjects’ decision making behavior.

Parental hypertension and cardiovascular response to stress in healthy young adults.

Abstract: One indicator of elevated risk for subsequent development of essential hypertension is the presence of the disorder in either or both parents. Exaggerated cardiovascular responsivity to stress has also been suggested as a possible precursor to hypertension. This study examined the relationship between parental hypertension and the heart rate (HR), systolic (SBP), and diastolic blood pressure (DBP) levels of 103 healthy college-age men, during two resting conditions and stressful cold pressor and reaction time tasks. Sons of hypertensive parents (N = 25) showed higher HR and SBP than sons of normotensive parents (N = 78) during both rest and stress, but these differences were greatest during the stressful reaction time (RT) task. No reliable differences in DBP were seen. A subsample of 45 subjects, including 14 with hypertensive parents, were also monitored during a second stress, the cold pressor test; only trends toward HR or BP differences related to parental hypertension were seen for this stress, although HR and SBP differences during the RT task were still significant (p<.05) even in this smaller group. Since the incidence of high blood pressure is known to be greater among the offspring of hypertensive parents, these findings suggest that cardiovascular responses to certain types of stress (e.g., active coping tasks) may help predict future risk of hypertension.

Psychopathy and Physiological Activity During Anticipation of an Aversive Stimulus in a Distraction Paradigm

Abstract: Two investigators independently rated 51 white, male prison inmates on a 7-point psychopathy scale (interrater reliability = .89). The combined ratings were used to divide the inmates into low (1), medium (M). and high (H) psychopathy groups of 17 subjects each. Following a sample trial, each inmate was given two trials in which he could choose how to spend his time during a 5–6 min wait for an aversive stimulus (120dB tone). Three choices were available: 1) continuous white noise, 2) a recording of a nightclub comedian, or 3) a continuous tone that changed in frequency 10 sec before delivery of the aversive stimulus. The aversive stimulus could be avoided on one trial but not on I he other (the order was counterbalanced). When the aversive stimulus was unavoidable (Trial UA), 46 (90.2%) of the inmates spent all or most of their time listening to the comedian, i.e., they adopted a “nonvigilant” strategy, while 38 (74.5%) adopted this strategy when the aversive stimulus was avoidable (Trial A). There were no group differences in the type of strategy used on either trial, or in the physiological responses given by the nonvigilant subjects on Trial UA. Group H tended to give smaller electrodermal responses and a larger increase in HR in anticipation of the sample tone than did Group L, a pattern that is consistent with previous research using classical conditioning or “count down” procedures. On Trial A the nonvigilant subjects in Group H showed a significantly smaller increase in nonspecific skin conductance activity than did Group L. It is suggested that making use of distraction when an aversive stimulus is avoidable results in less conflict and heightened emotional arousal in psychopaths than in other inmates. Some speculations on how psychopaths cope with threat are offered.

Visual Evoked Potentials Change as Heart Rate and Carotid Pressure Change

Abstract: The relationship between cardiovascular activity and the brain was explored by recording visual evoked potentials from the occipital regions of the scalp during systolic and diastolic pressure (Experiment I) and during fast and slow heartbeats at systolic and diastolic pressure (Experiment II). Visual evoked potentials changed significantly as heart rate and carotid pressure fluctuated normally, and these changes were markedly different in the right and left cerebral hemispheres. Evoked potentials recorded from the right hemisphere during various cardiac events differed significantly, whereas those recorded from the left did not. In both experiments, differences in the right hemisphere were due primarily to the PI component, which was larger at diastolic than at systolic pressure. The present findings are consistent with formulations from behavioral studies suggesting that baroreceptor activity can influence sensory intake, and suggest that hemispheric specialization may play an important role in the relationship between cardiac events, the brain and behavior. DESCRIPTORS: Carotid pressure. Evoked potentials. Heart rate, Baroreceptors. The early conception that sensory impulses are simply relayed from receptor to cortex was shaken when Granit and Kaada (1952) discovered that the central nervous systetn could control afferent fibers from muscle spindles. Since then, numerous studies have established that the brain can modulate its own sensory input by inhibiting or facilitating sensory transmission anywhere from the peripheral sense organs to the cortical level. In fact, it has been estimated that 10% of all afferent fibers contribute to centrifugal control mechanisms (Livingston, 1976), blurring the classical distinction between "sensory" and "motor" mechanisms. The brainstem reticular formation plays an important role in the centrifugal control of sensory processes. Both electrical stimulation and lesions (Livingston, 1959; Hernandez-Peon, 1961) of the reticuiar formation can facilitate or block interac

Parental Hypertension and Cardiovascular Response to Cognitive and Isometric Challenge

Abstract: The purposes of this investigation were to contrast the cardiovascular responses of sons of hypertensive and normotensive parents to tasks involving cognitive and isometric challenge, and lo examine the relationship of individual differences in heart rate (HR) reactivity to baseline blood pressure (BP) measurements. Thirty-six male, undergraduate volunteers (18 with and 18 without a parental history of hypertension) were scheduled for two, 1-hr experimental sessions (Days I and II). On Day 1, HR and BP measurements were obtained while subjects performed each of three laboratory tasks: a difficult test in concept formation, serial subtraction, and a sustained handgrip at 30% of maximum voluntary contraction. Each task lasted 3 min and was preceded by a 3-min baseline interval. On Day II, subjects were instructed to relax quietly while baseline measures of HR and BP were recorded. Relative to sons of normotensive parents, offspring of hypertensives exhibited higher mean Systolic BPs during all task periods; no corresponding group differences were observed on either Day I or Day II baseline recordings. Unlike SBP, Diastolic BP measurements did not vary reliably by parental hypertensive/normotensive status. Although the mean HRs of sons of hypertensives were significantly higher than in offspring of normotensives, these differences obtained uniformly across both the baseline and task intervals. Among subjects identified as High HR reactors during the two cognitive tasks, sons of hypertensive parents exhibited Day II baseline SBPs about 9 mmHg higher than did subjects without a parental history of hypertension. Among subjects identified as Low HR reactors, baseline SBPs did not differ reliably between sons of hypertensive and normotensive parents.

Somatosensory Evoked Potential Changes With a Selective Attention Task

Abstract: Somatosensory evoked potential (SEP) changes associated with selective attention were investigated. In 16 subjects, SEPs were recorded from five locations while they counted electrical stimuli to one of four randomly stimulated fingers. Sequential SEP events measured included peaks P30 (positivity at 30 msec). P45, N60, P100. N140. P190. N230, P400. Counting was associated with greater P45, P100. P190, N230, and P400 amplitudes; effects were not attributable to eye or tongue activity. Analyses designed to reveal changes associated with two conceptualized “channels” (finger class, hand) showed that the P45, P100, and P190 amplitude increases involved both channels. The P400 effect was limited to the target finger. Channel effects for N60 and N140 amplitudes resulted from decreases localized to the unattended element of one channel, suggesting “inhibition.” Latency effects involved mainly the hand channel; counted hand latencies were shorter for P30, P45, P100 and P190. The findings indicate modifications of both early and late electrocortical events with selective attention, and that changes can be of several kinds. They support the view that attention proceeds in more than one stage.

Effects of Control Over Aversive Stimulation and Type A Behavior on Cardiovascular and Plasma Catecholamine Responses

Abstract: Cardiovascular, plasma catecholamine, and behavioral effects of control over aversive events were studied in 87 Type A and B male adults. Subjects performed a choice reaction time (RT) task during which they received loud noise bursts and/or electric shocks on designated trials. About half of the cases were told they could avoid noise and shock by attaining a predetermined criterion of RT speed (Contingency). The remaining half were instructed that noxious stimulation would be delivered randomly, irrespective of their performance (No Contingency). Half of the cases in each treatment were exposed to high frequency of aversive stimulation (High FAS), whereas the remaining half received low frequency of such stimulation (Low FAS). Within Contingency, High and Low FAS were designed to signify failure and success, respectively. Aversive stimulation in No Contingency was gratuitous and, therefore, did not convey information about performance. Relative to No Contingency, the Contingency treatment induced greater increases in RT speed, systolic and diastolic blood pressure, and plasma epinephrine. Differential FAS did not potentiate these differences. It also was found that the Type A subjects had higher systolic blood pressure and heart rate responses than Type B's. The prediction that Contingency (particularly with High FAS) would elicit greater physiologic and behavioral hyperresponsiveness in A's than B's received some support in the data for RT speed and plasma NE. Findings were discussed in terms of sympathetic activation of hemodynamic changes under conditions of active coping. Consideration was given to the role of the sympathetic nervous system and Type A behavior in cardiovascular disease.

P300 and Slow Wave in a Message Consisting of Two Events

Abstract: This study is concerned with P300 and Slow Wave in an experimental paradigm in which information is transmitted by a combination of two successive events (a ‘message’). Each event delivered essential information for understanding the message, but the meaning of the message could not be determined until occurrence of the second event. The amount of information in each event was varied by varying its perceptual difficulty. Increasing perceptual difficulty causes an information loss, termed equivocation. A positive Slow Wave was elicited by both events. Slow wave was clearly increased in amplitude by equivocation in the eliciting event, and less clearly increased in amplitude by equivocation in the other event. The first event elicited a small P290 component. It could not be determined whether this component corresponded to P300. The second event elicited a large P300. This component was much reduced in amplitude by equivocation in the second event, but was only moderately reduced in amplitude by equivocation in the first event.

Arousing and De‐Arousing Effects of Cigarette Smoking Under Conditions of Stress and Mild Sensory Isolation

Abstract: The arousing and de-arousing effects of smoking a 1.3 mg nicotine delivery cigarette, measured by changes in electrodermal, heart rate and EEG alpha responding, were examined under conditions of stress, induced by aversive white noise, and mild sensory isolation. Compared with sham smokers and a situation control group, smokers showed significant arousal elevations in all response systems under sensory isolation conditions, but mixed stimulant (heart rate response) and depressant (EEG, skin conductance response) effects under stress conditions. Possible reasons for these differential effects are suggested.

A dose-response and time-action analysis of autonomic and behavioral effects of methylphenidate in attention deficit disorder with hyperactivity.

Abstract: Empirical attempts to correlate behavioral and physiological responses of hyperactive children to methylphenidate treatment have been complicated by methodological issues, including the demonstrated heterogeneity in the pool of hyperactive children, and the need to consider both dose-response and timeaction parameters of drug action. Ten hyperactive children, selected according to objective behavioral criteria, were each assessed in 3 placebo days and 3 drug treatment days varying in methylphenidate dosage. Heart rate, finger temperature, electrodermal variables, gross motor activity, serial reaction time (as a measure of attention), and impulsive errors of commission were measured before and at varying intervals following drug or placebo administration. Time-action curves of methylphenidate's effects on reaction time and on activity were dissimilar, with changes in reaction time more closely paralleling changes in the cardiovascular variables. These findings suggested that attentional deficit and inadequate motor inhibition represent divergent behavioral manifestations of hyperactivity, possibly corresponding to divergent neurophysiological substrates.

Physical symptoms associated with blood pressure.

Abstract: Two experiments employed within-subject designs to assess the degree to which selected physical symptoms correlated with systolic blood pressure (SBP) fluctuations. In the first study, 30 normotensive undergraduates (15 male and 15 female) participated in a series of 20 tasks and 20 baseline sessions, each lasting 1–2 min. Following each task or baseline, readings of systolic and diastolic blood pressure, heart rate, skin resistance, and finger pulse volume were taken. Immediately before the physiological measurements, subjects rated the degree to which they were experiencing each of 7 symptoms (e.g., sweaty hands, pounding heart). For each subject, simple correlations were computed between each of the symptoms and SBP across the 40 measurement periods. Forty-four percent of the subjects had at least one symptom-SBP correlation of + .70 or greater. Seventy-seven percent had at least one statistically significant symptom-SBP correlation. Between-subject analyses yielded no symptom-SBP relationships. The within-subjects correlation patterns varied from subject to subject, were internally consistent, and were related to sex and SBP variability. A second naturalistic experiment corroborated the findings. Theoretical and practical implications of the results are discussed.

Individual differences in heartbeat discrimination.

Abstract: In this experiment 41 subjects were trained to discriminate their own heartbeats and to discriminate an external signal. The subjects were divided into electrodermally labile and stabile subgroups. An important feature of the experiment was the development of a new procedure for assessing heartbeat discrimination, using signal detection theory methods. The results confirmed prior findings that subjects are unable to discriminate their own heartbeats without training, but that they can team such discrimination. It was also found that electrodermally labile subjects learned the heartbeat discrimination but electrodermally stabile subjects did not.

The Effects of Pharmacological Manipulations That Influence Vagal Control of the Heart on Heart Period, Heart Period Variability and Respiration in Rats

Abstract: Changes in heart period (HP), heart-period variance (HPV), and the respiratory component of HPV in freely moving rats were examined following pharmacological manipulations known to influence vagal control of the heart. Spectral analysis was used to quantify the component of HPV associated with respiration which is proposed to be sensitive to vagal influences on the heart. The respiratory component of HPV is described by a statistic, V, which is the sum of the spectral densities of the heart period spectrum across the band of frequencies associated with normal respiration. Vagal tone was reflexively enhanced by phenylephrine or peripherally blocked by atropine. Phenylephrine produced biphasic changes in HP and V, with the increases lasting from 0.5 to 2 hrs. Atropine resulted in significant decreases in HP, HPV and V. These decreases were immediate and sustained throughout the experiment, although there were signiflcant linear increases in HP and HPV from their initial post-injection values. In the saline condition, HP increased linearly across time. Results were discussed in terms of vagal and non-vagal control of the heart. It was suggested that, while all three variables are altered by manipulations of vagal influences on the heart, V seems to be influenced less by non-vagal control than HP and HPV.

Age, sleep deprivation, and performance

Abstract: Men 18–22 and 40–49 yrs old were repeatedly given a battery of monitoring, persistence, and cognitive tasks over an extended period of sleep deprivation. The older subjects, who generally exhibited superior performance, were also more affected by the acute deprivation of sleep.

External Anal Sphincter Response to Rectal Distention: Learned Response or Reflex

Abstract: Three experiments were conducted to determine whether the external anal sphincter contraction which typically follows rectal distention is a reflex or a voluntary response. Experiment I compared 15 chronically constipated patients to 10 normal subjects. A reflex should be reliably elicited by its unconditional stimulus; but if this response is voluntary, chronically constipated patients would be less likely to show it because they have had fewer opportunities to practice it. Only half of chronically constipated patients showed the response compared to 100% of normals. Experiment II investigated whether the response is elicited by rectal distention during sleep in 10 healthy subjects. The response was significantly less likely to occur during sleep. Experiment III in 6 normal subjects revealed that this response can be voluntarily omitted. These experiments indicate that external anal sphincter contraction following rectal distention is a voluntary response, not a reflex.

Hemispheric Specificity: A Physiological Concomitant of Hypnotizability

Abstract: MacLeod-Morgan (1979) found a significant relationship between hypnotizability and EEG hemispheric specificity. Hemispheric specificity is defined as the extent to which the alpha ratio between hemispheres changes during lateralized task performance. The present study was designed to replicate and extend this finding. EEG was recorded bilaterally from 44 subjects during performance of two right- and two left-hemisphere discontinuous tasks from MacLeod-Morgan (1979), and four new comparable continuous tasks. As predicted, significant differences were found in hemispheric specificity between low and high hypnotizables especially during the continuous tasks.

Amplitude and latency changes in the visual evoked potential to different stimulus intensities.

Abstract: Visual evoked potentials (VEPs) were recorded from five sites (T3, T4, Cz, O1, O2) to six intensities of light flashes. Peak-to-trough amplitudes were measured for the P100-N120 and N120-P200 waveforms as well as baseline (prestimulus)-to-peak amplitudes for each component (i.e. P100, N120, and P200). Different methods of defining augmenting/reducing were compared. These included subtracting the VEP epoch mean level from mean levels within a timeband corresponding to P100 and calculating slopes both for these values and for the P100-N120 amplitudes across intensities. The technique of using slopes to describe amplitude-intensity functions was found to be unjustified and misleading. The Augmenting/Reducing groups defined by the slopes of peak-to-trough amplitudes or slopes of the timeband “amplitudes” proved to be almost mutually exclusive. Results also showed that the frequency with which actual VEP peaks occur within the appropriate timeband is very low and differs topographically. Augmenting/Reducing was then defined by monotonic increases in the P100-N120 peak-to-trough amplitudes. Augmenters and Reducers differed from each other not only for amplitude-intensity patterns but on a number of latency measures. Hemisphere differences were also found between groups. An inverse relationship was found between occipital and vertex amplitude-intensity patterns such that vertex augmenting was accompanied by occipital reducing and vice versa. Temporal and vertex amplitude-intensity patterns were similar.

Physical Anhedonia and Future Psychopathology: An Electrocortical Continuity?

Abstract: During the past decade, a great deal of effort has been focused on the identification of subjects who may be at “high-risk” for the development of psychopathology. Chapman, Chapman, and Raulin (1976) suggested that college students who report pervasive physical anhedonia may comprise a group of subjects vulnerable to the development of schizophrenia. The present study provides cortical evoked potential data consistent with this relationship. Auditory event-related potentials (ERPs) were collected from anhedonic subjects and normal controls under two conditions of auditory stimulation. In the first condition (nonsignal orienting), anhedonic and normal control subjects did not differ on any measure of the ERP. However, under signal conditions, reliable group differences emerged which were strikingly apparent in the late positive (P3) component. These group differences were maximal when the auditory signal predicted a high-interest event. Similar observations of reduced P3 activity have been frequently reported in studies with schizophrenic patients. In conjunction with previous investigations of anhedonic subjects, the present data continue to support the hypothesis that these subjects may constitute a psychosis-prone population.

Novelty and Significance Effects in the Fractionation of Phasic OR Measures: A Synthesis with Traditional OR Theory

Abstract: The unitary Orienting Response (OR) concept developed by EN Sokolov has been interpreted as requiring the covariation of a range of physiological indicators in response to manipulation of stimulus intensity, novelty and significance After failing to find such a covariation, Barry (1979) proposed a four-way fractionation of response indicators as an alternative to unitary OR theory This fractionation was explored here in two experiments involving manipulation of novelty and significance These confirmed the predicted fractionation and clarified the role of electrodermal responses relative to traditional OR theory It was then proposed that this fractionation of responses reflected preliminary processes in OR elicitation, allowing a synthesis of Barry's response fractionation and Sokolov's traditional OR The possible role of Maltzman's cortical set theory’ in such a synthesis was outlined

The effects of slow cortical potentials on response speed.

Abstract: The relationship between slow cortical potentials (SCPs) and response speed was investigated by training subjects to induce different cortical shifts by means of a biofeedback procedure. During two identical experimental sessions trials with visual feedback of the actual DC-shifts alternated with reaction time trials without feedback. In reaction time trials only the signal for the required change in polarity was provided. At the end of the signal interval an immediate button-press was required to stop a hissing noise. Two groups of 10 subjects each were investigated, one group receiving feed back from the left precentral recording(C3) and the other from the right precentral recording (C4). Results showed that subjects achieved control over their SCPs. At the end of the training period in the second session significant differences in SCPs between trials of the different required polarities were observed, during feedback trials as well as during reaction time trials without feedback. Subjects responded faster during trials in which a change toward more cortical negativity was required as compared to trials requiring less negativity.

Cardiac output and blood flow distribution during rest and classical aversive conditioning in monkey.

Abstract: Cardiac output was measured by dye dilution in rhesus monkeys (n = 9) during rest and classical aversive conditioning. A 1- min tone (followed by unavoidable electric shock) served as the conditional stimulus (CS +). Cardiac output was determined at approximately 30 sec before and after onset of CS +. Conditional increases in mean blood pressure (78± 11 to 84±11 mmHg. average±SD) and heart rate (145±23 to 166 ± 31/min) were associated with a significant (p<.01) increase in cardiac output (1.32 ± .25 to 1.69±.51 L/min) and decrease in total peripheral resistance (60.8 ± 13.7 to 53.1 ± 14.8 mmHg/L/min). There were no significant changes in these variables during a different tone (CS-) which was never followed by shock. Infusion of radio-labeled microspheres (5 monkeys) at 25-30 sec after CS + onset revealed a conditional increase (vs resting control) in flow to the diaphragm and certain other skeletal muscle; myocardial blood flow was not increased at this time. Flow decreased to the kidney, liver and pancreas. Elimination of the conditional increase in blood How to skeletal muscle following administration of propranolol (3 monkeys) suggests that the redistribution of cardiac output during “stress” may involve an active adrenergic vasodilation in the non-human primate.

Magnitude of Incentive Effects on Heart Rate

Abstract: Previous demonstrations of monetary incentive effects on heart rate during a continuous motor task were extended by employing different magnitudes of incentive: 0¢ (feedback only), 2¢, and 5¢ per response. The influence of the total amount of monetary incentive for the experiment was examined by providing monetary incentives either for only 2 trials or for all 5 trials. This procedure also provided an evaluation of the effect on heart rate during the later trials of discontinuing the incentive after 2 trials. The results showed a clear and graded effect of the amount of incentive per response, but no significant effects were obtained for the total amount of incentive, in spite of providing subjects with clear feedback as to how much money they could expect. Discontinuing incentives produced a significant decrease in heart rate, compared to subjects who continued to receive incentives. No effect was found for the magnitude of incentive on the rate of responding on the motor task, rendering unlikely an explanation for the results in terms of cardiac-somatic coupling. Also, any possible contribution to the heart rate results from frustrative nonreward feedback was eliminated by avoiding any suggestion of failure feedback on the task. It was concluded that the effects are attributable to the incentive value of the monetary reward and that they are large enough to be of considerable interest.