摘要:

ABSTRACTTwenty‐two normal young men received a counterbalanced and double blind administration of 20 mg methylphenidate and placebo. Two tasks were administered in counterbalanced order: an uninterrupted 45‐min vigilance test and a paired‐associates learning test. As previously reported, under placebo, accuracy and speed decreased monotonically over the course of the vigil. This degradation of performance was significantly reduced by the stimulant drug. Event‐related potentials (ERPs) were derived for correctly detected targets and nontargets. The most salient pharmacologic effects involved a late positive wave (P464) identified as P3b. Methylphenidate reversed or reduced the decrease in amplitude and increase in latency of P464 present over phases of the placebo session. The results suggest that the stimulant‐induced improvement in performance may be mediated by enhancement of evaluation processes.In the paired‐associates test there were no pharmacologic effects. Instead there was an unexpected, pronounced improvement in learning in the second session, irrespective of the substance administered. However, the ERP evoked by the “stimulus” cue of each pair was systematically related to the achievement of learning criteria. A late positive was identified as P3b (P555) increased significantly in amplitude following the attainment of learning. There were no amplitude changes among ERPs evoked in the early post‐criterion, late post‐criterion, or overlearning “phases.” Nor were there amplitude changes between early and late pre‐criterion categories. Thus, ERP amplitude displayed a binary association with th

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1984.tb00247.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1984.tb00248.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

ABSTRACTA multivariate pattern‐classification system was developed for the study of facial electromy‐ographic (EMG) patterning in 12 female subjects during affect‐laden imagery and for posed facial expressions. A parameter‐extraction procedure identified the dynamic EMG signal properties which accorded the maximal degree of self‐reported emotion discrimination. Discriminant analyses on trialwise EMG vectors allowed assessment of specific EMG‐site conformations typifying rated emotions of happiness, sadness, anger, and fear. The discriminability among emotion‐specific EMG conformations was correlated with subjective ratings of affective‐imagery vividness and duration. Evidence was obtained suggesting that the EMG patterns encoded complex, “blended” reported affective states during the imagery. Classification analyses produced point‐predictions of reported emotional states in 10 of the 12 subjects, and provided the first computer pattern recognition of self‐reported emotion from psycho

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1984.tb00249.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

ABSTRACTForty‐one young male subjects performed either an easy or moderately difficult arithmetic task with the opportunity to earn a monetary incentive if they did well. Cardiovascular (heart rate, systolic and diastolic blood pressure) and subjective responses were assessed immediately prior to and 5 min following task performance. Results indicated greater systolic (SBP) responses during the Pre‐task period for subjects expecting to perform the difficult task. Behavior pattern classifications based on the Jenkins Activity Survey revealed Higher Pre‐task heart rate (HR) elevations among Type As compared to Bs in the Difficult task condition, and greater Pre‐task SBP responses in As compared to Bs irrespective of task difficulty. There also was some evidence of an association between SBP reactivity and scores on the Thurstone Activity scale. Change‐scores reflecting SBP and HR reactivity were correlated in the Pre‐task period of the Difficult but not the Easy condition. Predictions regarding the impact of motivational arousal upon goal attractiveness were not supported, possibly for methodologi

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1984.tb00250.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

ABSTRACTThe preparedness theory of phobias implies that fear‐relevant stimuli are biologically contrapre‐pared for safety‐signal conditioning. Thus it should be very difficult to establish a pictorial snake as a safety‐signal predicting the absence of shock in a Pavlovian conditioned inhibition paradigm. Since this contrapreparedness is postulated as species‐wide, the snake stimulus should be an ineffective safety‐signal even in those subjects who do not fear snakes. In contrast, the prior fear hypothesis suggests that this difficulty should occur only in those subjects who already fear snakes. To test these hypotheses, subjects reporting either high or low snake fear were exposed to electrodermal conditioning trials designed to establish a fear‐relevant CS (a pictorial snake) and a fear‐irrelevant CS (a pictorial flower) as safety‐signals by nonreinforcing each in compound with a fear‐eliciting CS. The results provided marginal support for the pr

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1984.tb00251.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1984.tb00252.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

ABSTRACTReflex responses from eyelid muscles were evaluated when subjects prepared to or made brief or sustained voluntary contractions of eyelid or forearm muscles in a signaled reaction time task. The eyeblink reflex consists of an early and unilateral response, R1, and a longer latency bilateral response, R2. A similar pattern of reflex excitability was observed for all phasic movements. The R1 was transiently potentiated by the warning stimulus, increased again at the end of the preparatory period, increased more in the reaction interval and immediately after movement onset, and finally declined to control levels by 500 ms after onset of voluntary movement. The R2 responses were typically depressed at the same times that R1 responses were enhanced. When sustained contractions were performed and reflexes were elicited after movement eyelid onset, the patterns of early R1 enhancement and R2 depression occurred, both for about 500 ms, and gave way to continued R1 and also R2 enhancement as long as eyelid movement continued. The different behavioral responses of R1 and R2 reflect differences in the physiological properties of the separable neuroanatomical pathways for the two eyelid reflex responses.

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1984.tb00253.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

ABSTRACTPower spectral analysis was performed on the visual evoked potentials (VEPs) of subjects who had participated in an augmenting‐reducing study. Six flash luminances were used (0.31, 0.65, 1.25, 2.5, 5.0, and 10.0 fL). EEG recordings were taken from CzO1, O2, T3, and T4scalp locations. Power in six frequency ranges was examined (0–2, 2–6, 6–10, 10–14, 14–18, and 18–22 Hz). Power in the lowest three frequency ranges increased linearly with stimulus luminance at all electrode sites. Power in the highest three ranges increased linearly with luminance at occipital sites only. Power was greater in the left hemisphere than in the right for 18–22 Hz activity recorded at occipital locations. The reverse asymmetry occurred for 6–14 Hz activity recorded at temporal locations. The results suggest that individual differences in stimulus control in EEG recordings taken from scalp locations overlying nonspecific cortex are due primarily to the contributions of higher frequency components of the VEP spectrum. A thalamo‐cortical model of stimulus c

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1984.tb00254.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

ABSTRACTThe effects of biofeedback and voluntary control procedures on systolic blood pressure and heart rate during postural change were investigated in 30 normotensive men. Systolic pressure was measured with a continuous blood pressure tracking cuff, and blood pressure feedback was provided on a beat‐to‐beat basis. Postural changes in pressure, and corresponding heart rate changes, were examined in three experimental groups (N = 10 each). In two groups, subjects were given feedback training to increase or to decrease systolic blood pressure. In the third group, subjects were simply asked to increase their pressure but were not given feedback about their performance. Voluntary control of systolic pressure was attempted while subjects were seated and during postural change—sitting to standing. Subjects were also instructed to maintain voluntary blood pressure control in subsequent no‐feedback test trials. During postural change, voluntary control procedures caused significant alterations in tonic levels of systolic pressure, but phasic blood pressure reactivity was unaffected. With respect to postural changes in heart rate, both tonic and phasic treatment effects were observed. Implications of the findings for basic and clinical research are di

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1984.tb00255.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1984.tb00256.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY