Wolfram Boucsein

Dissociation of decision-making under ambiguity and decision-making under risk in patients with Parkinson's disease: A neuropsychological and psychophysiological study

Decision-making impairments in Parkinsons disease (PD) are most likely associated with dysfunctions in fronto-striatal loops. Recent studies examined decision-making in PD either in ambiguous situations with implicit rules, using the Iowa Gambling Task (IGT), or in risky situations with explicit rules, using the Game of Dice Task (GDT). Both tasks have been associated with the limbic-orbitofrontal-striatal loop, involved in emotional processing. However, the GDT has additionally been highly associated with the dorsolateral prefrontal-striatal loop, being involved in executive functions. The present study is the first one which examined decision-making in PD patients with both, IGT and GDT. We studied 21 non-demented PD patients on dopaminergic medication and 23 healthy controls with both tasks and a neuropsychological test battery with focus on executive functions. To analyse possible abnormalities in emotional processing, electrodermal responses (EDRs) were assessed while performing the tasks. We found that PD patients were significantly impaired in the GDT, but not in the IGT. Executive dysfunctions correlated with GDT but not with IGT performance. In both tasks, PD patients showed significantly reduced feedback EDRs after losses, but not after gains, indicating a primary decline of sensitivity to negative feedback. Our behavioural data suggest that dysfunctions in the dorsolateral prefrontal loop might be stronger than in the limbic loop, resulting in deficits in executive functions and GDT performance but unimpaired IGT performance. Reduced sensitivity to negative feedback is discussed with regard to dysfunctions in the limbic loop, which may result from pathology of limbic structures or dopaminergic medication.

Effects of stimulus intensity, risetime, and duration on autonomic and behavioral responding: implications for the differentiation of orienting, startle, and defense responses.

The effects of stimulus intensity, duration, and risetime on the autonomic and behavioral components of orienting, startle, and defense responses were investigated. Six groups of 10 students were presented with 15 white noise stimuli at either 60 or 100 dB, with controlled risetimes of either 5 or 200 ms, and at stimulus durations of 1 or 5 s (1 s only in the case of the 60-dB groups). A dishabituation stimulus consisting of a 1000 Hz tone was also presented. Measures consisted of skin conductance and heart rate, together with ratings of facial expressions and upper torso movement obtained using video recording. Increased intensity resulted in greater amplitudes and frequencies of electrodermal and behavioral responses, and a change from cardiac deceleration to acceleration. Faster risetimes elicited larger electrodermal responses, greater frequencies of eye-blinks, head and body movements, and larger cardiac accelerations. The effects of duration for the 100-dB stimuli were less clear-cut. Overall, the results are discussed in relation to the differentiation of orienting, startle, and defense responses.

Experimental investigation of psychophysiological stress-reactions induced by different system response times in human-computer interaction∗

In human-computer interaction, system response times are considered to have important effects on operator performance and stress response. To evaluate the effects of short (2s) and long (8s), as well as constant and variable, system response times, a laboratory study was conducted with 68 subjects in four independent groups working at a simulated computer workplace. Subjects had to perform a simple detection and correction task at a visual display terminal in six trials of 20min each, the first being a training trial with identical conditions for all subjects. Performance and physiological measures (heart rate, electrodermal activity, and blood pressure) were taken during the trials, and subjective measures of mood and physical state as well as physiological measures were done in the resting periods iiftcr the trials. In addition to a general adaptation effect over the trials, experimental effects were shown mainly for the duration factor: subjects under conditions of long, as compared to those under shor...

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.

Combining electrodermal responses and cardiovascular measures for probing adaptive automation during simulated flight

Adaptive automation increases the operators workload in case of hypovigilance and takes over more responsibility if workload becomes too high. Two consecutive studies were conducted to construct a biocybernetic adaptive system for a professional flight simulator, based on autonomic measures. Workload was varied through different stages of turbulences. In a first study with 18 participants, electrodermal responses of experimental subjects oscillated very close to the individual set point, demonstrating that workload level was adjusted as a result of adaptive control, which was not the case in yoked control subjects without adaptive automation. Combining electrodermal responses with heart rate variability in a second study with 48 participants further enhanced the adaptive power which was seen in even smaller set point deviations for the experimental compared to the yoked control group. We conclude that the level of arousal can be adjusted to avoid hypovigilance by combining autonomic measures in a closed loop.

Design of work/rest schedules for computer work based on psychophysiological recovery measures

Abstract Ambulatory assessment of cardiovascular, electrodermal and electromyographic activity was used to monitor different kinds of strain during eight hours of highly demanding computer work under different work/rest schedules. Eleven patent examiners performed their complex visual display task under two different break regimes in counterbalanced order: 7.5 min break after 50 min work on one day and 15 min break after 100 min work on the other day. Short breaks were more effective in promoting recovery from both mental and emotional strain until the early afternoon, while the long break was more effective in reducing fatigue and emotional strain in the late afternoon. Recovery from muscular strain was greater during scheduled rest breaks compared to unpredictable breaks such as system breakdowns and interruptions by colleagues, but the increase of electrodermal activity was also higher, pointing to the possibility of increased emotional strain as a consequence of a rigid break schedule. Relevance to industry Psychophysiological monitoring was able to show that workers performing highly demanding computer-based work benefit more from short, frequent breaks during the morning and longer, less frequent breaks in the afternoon.

A psychophysiological model of emotion space

Despite a wide variety of emotions that can be subjectively experienced, the emotion space has consistently revealed a low dimensionality. The search for corresponding somato-visceral response patterns has been only moderately successful. The authors suggest a solution based on an assumed parallelism between emotion coding and color coding. According to the color detection model proposed by Sokolov and co-workers, neurons responsible for color detection are triggered by a combination of excitations in a limited number of input cells. Similarly, a limited number of input channels may feed complex emotion detectors being located on a hypersphere in a four-dimensional emotion space, the three angles of which correspond to emotional tone, intensity, and saturation, in parallel to hue, lightness, and saturation in color perception. The existence of such a four-dimensional emotion space in the subjective domain is shown by using schematic facial expressions as stimuli.A neurophysiological model is provided in which reticular, hypothalamic, and limbic structures constitute input channels of an emotion detecting system, thus acting as the first layer of emotion predetectors. Hypothalamic neurons with differential sensitivity for various transmitters may elicit a subsequent selective activation in a second layer of predetectors at the thalamic level. The latter are suggested to trigger emotion detectors located in cortical areas, the action of which should be revealed by measures of central nervous system activity. Preliminary results from evoked potential studies show that switching between schematic faces that express different emotions may be used as an objective measure for establishing a psychophysiological emotion space.

Psychophysiological stress effects from the combination of night-shift work and noise

The influence of night-shift work and noise on arousal and stress reactions have, to date, been investigated separately. The aim of this study was to compare their psychophysiological effects in combination. Twenty-four male student subjects continuously performed ten hours of visual display tasks per 24 h under highly controlled conditions for either five consecutive day or night shifts, followed by two days of rest. Each group worked in conditions of simulated traffic noise, at either 80 or 50 dB(A). Urinary catecholamines, electrodermal activity, heart rate, and ratings of mood and physical symptoms were recorded continuously or at specified intervals. Catecholamine excretion rates, autonomic reactions, reaction times, and ratings of subjective alertness showed changes typical for night-shift work. No main effects of noise were found, but significant interactions between the two experimental factors reflected differential actions of noise dependent on the type of shift. The results favor a multiple-arousal concept. Night-shift work primarily influences general arousal, while noise affects both general and goal-directed arousal, dependent on the presentation during day or night shift.

Effects of different stress settings on cardiovascular parameters and their relationship to daily life blood pressure in normotensives, borderline hypertensives and hypertensives

The aim of this study was to compare a traditional stress setting, consisting of two mental arithmetic tasks and two Stroop test modifications, and a stress setting of varying task demand and decision latitude according to Karaseks job strain model, with respect to their feasibility to elicit differences in cardiovascular reactivity and recovery in 20 normotensives, 20 borderline hypertensives, and 20 non-medicated hypertensives, carefully selected by means of World Health Organization criteria. In addition, the relationship between laboratory and everyday blood pressure was investigated. All subjects were tested under both stress settings in counterbalanced order. Blood pressure was recorded both intermittently from the brachial artery (Riva-Rocci) and continuously from the finger (Finapres). Heart rate and electrodermal activity were continuously measured as well. Furthermore, daily life blood pressure recorded by means of 24 h ambulatory monitoring during a normal working day served as criterion for the re-classification of the blood pressure groups by means of discriminant analysis using physiological recordings from baseline, test phases and rest phases. The groups did not show significant differences in their reactivity to the various mental stressors including the Karasek-model oriented ones but marked differences in their behaviour occurred during the 10 min of recovery following each stress setting. Both systolic and diastolic blood pressure in hypertensives failed to recover during this period. The results also showed the superiority of the Finapres method with respect to reflecting the dynamics of physiological recovery processes. None of the stress settings showed an advantage in predicting blood pressure in daily life. In general, the results question the validity of mental laboratory stressors for the prediction of cardiovascular changes in daily life but point to a possible role of recovery processes after stress in the development of essential hypertension.

Methodological Issues in Electrodermal Measurement

Electrodermal recording has been extensively used for more than a century, but serious attempts to standardize recording and evaluation have not been performed since the early seventies. The Society for Psychophysiological Research has published a consensus of an expert committee (Fowles, Christie, Edelberg, Grings, Lykken, & Venables, 1981). Despite this, conflicting methodology still persists in electrodermal research and application. Perhaps this is in part the result of the committee’s concentration on electrodes, jelly, placement, and preparation of sites. On the other hand, some central issues which had been raised by (1967) and by (1971), have not attracted much attention of the commission. The aim of this paper is to bring up these issues again, in order to discuss recommendations given earlier with respect to more recent empirical work.