A Direct Comparison of the Skin Conductance and Skin Resistance Methods

The purpose of the present study was a direct comparison between simultaneous recordings of skin conductance and skin resistance. Sixty male students received a series of 30 white noise stimuli, while measures were taken continuously from four sites on the palmar surfaces of the fingers. Evaluations were made for response amplitudes, recovery, and for an approximate area measure. Magnitude of reactions and reliabilities were compared using ANOVA procedures. Behavioral concordances were estimated as correlations with the subjects' ratings of stimulus intensities. Conductance and resistance measures do not differ in amplitude, in area, or in strength of their reliabilities and behavioral concordances. No differences in any respect are found between sites. Skin conductance yields significantly (p < .01) shorter recovery times than skin resistance, which is discussed in terms of membrane permeability change.     

Impaired emotional learning and reduced amygdala size in schizophrenia: a 3-month follow-up

Individuals with schizophrenia have difficulties in emotional information processing. A relationship between behavioral variables of emotional processing and structural amygdala alterations in schizophrenia has been proposed but not shown, yet. Morphological studies of amygdala size in schizophrenia have yielded inconsistent results. The current study assessed paired associates learning of emotional and neutral faces in 16 subjects with schizophrenia during acute episode and in relative remission after 3 months. Sixteen matched controls were studied for comparison. Subjects also underwent structural magnetic resonance imaging (3D-MRI) at the first time of assessment. Subjects with schizophrenia showed a significant decrease (by 13%) in total size of the amygdala compared to controls, which was more pronounced on the right side. Subjects with schizophrenia improved associative learning of facial identities but not of emotional facial expressions after relative remission of psychotic symptoms. Volume of the right amygdala in subjects with schizophrenia and in controls was significantly related to emotional learning, indicating better learning in subjects with larger amygdala size. Our results indicate that subjects with schizophrenia have a deficit to form associations when emotionally loaded material is used. This deficit seems to be trait-like and independent of disease state. It seems to be linked to size reduction of the right amygdala in schizophrenia.     

Effects of a Warning Signal on Reactions to Aversive White Noise Stimulation: Does Warning “Short-Circuit’ Habituation?

Reduced autonomic and subjective reactions to aversive stimuli under predictable as compared to unpredictable conditions have been explained on the one hand by the mechanism of preception and on the other hand by orienting response (OR) reinstatement in the unpredictable condition, with differences in rated aversiveness not necessarily being involved. To test differential predictions based on an habituation vs. preception position, as suggested by Lykken and Tellegen, one group of male volunteers was presented with 30 trials in which the onset time of an aversive white noise tone (110dBA) was signalled, while in the other group the onset time was not signalled. A control group received unsignalled presentations of 70dBA white noise tones. Following each trial, subjects indicated the aversiveness of the white noise at its impact. SCRs were recorded continuously. Responses produced by the signalled tones decreased over trials, while responses produced by the unsignalled 110dBA tones increased over trials. The control group exhibited a continuous decrease. Self-report measures showed an overall decrease over trials but no differential decline. It was concluded that an OR reinstatement interpretation seems to be best in line with the data, although the observed functional significance of signalling at the autonomic level needs further evaluation to arrive at a clear distinction between OR theory and the preception hypothesis.     

The effect of chlordiazepoxide on the anticipation of electric shocks

The action of 20 mg chlordiazepoxide upon two different anxiety-evoking conditions in comparison with a control condition was investigated in a doubleblind, placebo controlled study with 90 healthy male students. The Ss were told to expect an electric shock two times as strong under one condition and five times as strong under the other one in relation to a shock they had previously found unpleasant. During the anticipation interval of 20 min duration HR, GSR, respiration rate, and a rating of subjective emotional arousal were continuously recorded. The greatest effects of stress could be observed within the last 2 min of the anticipation interval, while interactions between drug- and stress-conditions occurred only at the beginning of the 20-min interval. Under the strong stress condition chlordiazepoxide showed an anxiety-reducing effect, under the control condition, however, paradoxical effects.     

Multivariate investigation of reactions to tranquilizers dependent on personality variables (author's transl)]

5 mg of diazepam as well as 2.5, 5, and 10 mg of a substance from the thienodiazepine series (Bay g 5653) were compared with a placebo, following a double-blind procedure. The 149 male student volunteers were classified into introverts and extraverts. For 17 test variables including subjective and physiological measures, as well as psychomotoric and cognitive achievement variables, a 2 x 5-factorial MANOVA was computed. Effects of medication and of interactions between introversion/extraversion and medication were highly significant. Correlations of test variables with composite scores indicated that medication effects could be shown best with objective tests, while the interactions between introversion/extraversion and medication could be shown better with subjective variables. Results were discussed together with those of an earlier univariate analysis of the data using emotional stability/lability as a personality variable.     

Social–physiological compliance as a determinant of team performance

A cybernetic model of behavior predicts that team performance may depend on physiological compliance among participants. This laboratory study tested if compliance in electrodermal activity (EDA), heart rate or breathing in two-person teams (N=16) was predictive of team performance or coordination in a continuous tracking task simulating teleoperation. Visual contact among participants was manipulated. Physiological compliance was scored with weighted coherence and cross correlation. Separate multiple regression analyses revealed that the task completion time was predicted by coherence measures for EDA and heart, but only at a trend level for breathing. Task completion time was also predicted by heart cross correlation. Team tracking error was predicted by coherence measures for EDA, heart and breathing, and also heart cross correlation. While social–visual contact did not have an impact, physiological compliance was predictive of improved performance, with coherence robust over all three physiological measures. Heart cross correlation showed the strongest predictive relationships. These results provide evidence that physiological compliance among team members may benefit team performance. While further study is needed, physiological compliance may someday provide a needed tool for the study of team work, and an objective means to guide the ergonomic design of complex sociotechnical systems requiring a high degree of team proficiency.     

State-dependent implicit learning deficit in schizophrenia: evidence from 20-month follow-up

Previous research has confirmed stable explicit memory deficits in schizophrenia across disease states. However, little is known about the implicit learning capabilities of individuals with schizophrenia across the course of illness. The current study assessed procedural learning in 19 schizophrenia subjects (DSM-IV criteria) and 19 matched controls using the Serial Reaction-Time Task (SRTT). The severity of negative, positive and disorganized symptoms was assessed using the Scales for the Assessment of Positive and Negative Symptoms. A sub-sample of 11 schizophrenia subjects and 11 controls was reassessed 20 months later when symptoms in the schizophrenia subjects had largely remitted. Schizophrenia subjects were severely impaired on sequence-specific procedural learning during an acute episode. This deficit could not be explained by a general memory or processing speed impairment. Impaired implicit learning scores were significantly related to higher ratings of disorganized symptoms. However, 20 months later, when acute symptoms had remitted, the performance of the schizophrenia subjects on procedural learning had normalized. Our findings might share a conceptual overlap with previous reports of a reduced ability of schizophrenia subjects during an acute episode to adapt ongoing perceptual and behavioral programs to previously experienced regularities in their environment.     

Controlling synaptic input patterns in vitro by dynamic photo stimulation

Recent experimental and theoretical work indicates that both the intensity and the temporal structure of synaptic activity strongly modulate the integrative properties of single neurons in the intact brain. However, studying these effects experimentally is complicated by the fact that, in experimental systems, network activity is either absent, as in the acute slice preparation, or difficult to monitor and to control, as in in vivo recordings. Here, we present a new implementation of neurotransmitter uncaging in acute brain slices that uses functional projections to generate tightly controlled, spatio-temporally structured synaptic input patterns in individual neurons. For that, a set of presynaptic neurons is activated in a precisely timed sequence through focal photolytic release of caged glutamate with the help of a fast laser scanning system. Integration of synaptic inputs can be studied in postsynaptic neurons that are not directly stimulated with the laser, but receive input from the targeted neurons through intact axonal projections. Our new approach of dynamic photo stimulation employs functional synapses, accounts for their spatial distribution on the dendrites, and thus allows study of the integrative properties of single neurons with physiologically realistic input. Data obtained with our new technique suggest that, not only the neuronal spike generator, but also synaptic transmission and dendritic integration in neocortical pyramidal cells, can be highly reliable.