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unique and suggests that a more general neurochemical effect of ethanol is responsible for the enhancement of the psy- chophysiological effects of these drngs.

EVENT-RELATED POTENTIALS DURING FINGER TAPPING

T. Radii, L. Maras, Z. Bohdaneck3~ and M. Indra Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic

Event-related potentials (ERPs) were recorded by means of a 16-channel EEG brain-mapping system during tapping experi- ments, the task of the subjects being to synchronize with the rhythm of isochronous tonal sequences. Inter-tonal intervals (ITIs) were either 700 or 4800 ms. It has been found in previous experiments and confirmed in the present ones that, in contrast to the short ITIs, it is impossible to maintain the rhythm for the longer ITIs. This is combined by a disappear- ance of stimulus anticipation (responses precede tones) which is replaced by usual reaction times (responses follow tones). ERPs were recorded during listening to tonal sequences mo- tionless, listening and tapping (ERPs triggered by tone or tapping onsets); tapping spontaneously with equal speed ap- proximately. ERPs (both auditory and motor components) were of lower amplitude for ISI 700 than 4800. Besides that tapping added to mere listening to the tones reduced the amplitude of ERP-s in both cases. Differences might be caused mostly by the circumstance that at ISI 700, the stimu- lus sequence is being perceived and rhythmic motor perfor- mance programmed as a coherent whole, whereas at 4800 ms each stimulus is being detected and tapping movement pro- grammed separately.

TESTlNG SENSOMOTORIC CAPACITY BY A COM- PUTER-AIDED TRACKING SYSTEM

M. Plietz, L. Beyer and R. Rost Institute of Physiology, University of Jena, Jena, Germany

In rehabilitation of motor disorders there are many subjective possibilities to evaluate progress in regaining control of motor skills. We have developed a computer aided system with pursuit tracking. By the help of this system movements can be standardized and results compared.

Test persons are required to follow a time-variant move- ment displayed on computer screen by moving their arm of leg. Movements are displayed on the same screen to give feedback and measured by a connected sensor, i.e., a go- niometer, and stored in computer memory for further prepa- ration. To test sensorimotoric capacity several request func- tions may be chosen, i.e., sequences of jumps, sinusoidal waves, stochastic functions.

By adaption of linear model theory parameters can be calculated estimating real movements: transfer function and

describing parameters in time, amplitude and velocity range; frequency transmission function by sinusoidal request and describing parameters in the amplitude and frequency range; estimated statistical parameters.

Performing sine movements (0.3 to 1.5 Hz; angle 105°+ 18 ° in elbow), the quality of motor output under normal condi- tions remains stabile. Higher frequencies show increasing error integrals and significant better performance of elbow than knee movements caused by different biomechanical con- dition. Our test may be applied with a PC-AT Computer in different task of motor diagnostics and psychopysiological experiment.

INFLUENCE OF COLOR ILLUMINATION ON AG- GRESSIVITY OF SEA FISH SERRANUS SCRIBA

J. Radilo% ~ and N. KovafzevK b " Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic and h Department of Marine Biology, Kotor, Montenegro

In previous experiments, we have shown aggressivity of Ser-

ranus scriba (Ss) to its own image in the mirror. In this study, we have examined the influence of color illumination (green, red) or semidarkened daylight on the aggressivity of this fish measured by a mirror test. Ss caught recently before the experiments were kept in a glass aquarium with fresh sea- water. A separate testing aquarium, illuminated in random order either with red or green 40 W lamp, or by dim daylight, was used. One dioptry magnifying mirror was placed into this aquarium and aggressivity scored. Significantly higher aggres- sivity was found under red light exposure in comparison with green and dim daylight in all Ss with considerable differences. Dim and green illumination did not differ significantly. Our finding points to phylogenetic aspects of emotional influence of red color causing increase in aggressive behavior.

SENSITIVITY OF THE T-WAVE AMPLITUDE TO BE- HAVIORAL TASKS AND BETA-ADRENERGIC BLOCK- ADE

Harald Rau Department of Clinical and Physiological Psychology, Eber- hard-Karls University Tfibingen, Tiibingen, Germany

Phasic changes of the amplitude of the T-wave of the electro- cardiogram have been considered to indicate changes in the activity of the beta-adrenergic part of the sympathetic nervous system. Behavioral or pharmacological manipulations result in effects on the phasic behavior of the T-wave which verify the assumption that these T-wave modulations reflect changes in the beta-adrenergic sympathetic system: (1), Tasks involving active coping, in contrast to passive coping, elicited marked decreases in the amplitude of the T-wave. (2), This effect could be blocked by the application of pharmacological beta-