224 Abstracts /International Journal of Psychophysiology300 (1998) 95-271 tions of visual and oculomotor cortex neurons when visual stimulus inclose to the parafoveal zone. Amplitude of the rapid presaccadic potentials prior to right direction saccades (both 10 and 20 degrees) were larger then left ones. That could be associated with functional advantage of a nosal retina part where visual stimuli from right hemifield are projected. The dominance of left cortex hem is here in ma- jority of subjects also plays a role. 588 THE EFFECTS OF CAFFEINE AND CLONIDINE ON EYE MOVEMENTS C.F. Brice, N. Rich, A. Smith and D. Nutt University of Bristol, Department of Experimental Psy- chology, Bristol, UK Introduction: The present study examined the effects of 200 pg clonidine (an alpha 2-adrenoceptor agonist) and low doses of caffeine (1.5 mg/kgl on performance of a range of tasks (selective and sustained attention, simple and serial reactioh / time), saccadic eye movements and subjective mood. Measures of blood pressure and heart rate were also. recorded. Method: A between subjects design was employed. 24 male participants performed in one of 4 conditions (caffeine/placebo, caffeine/clonidine, de- caffeinated/placebo, decaffeinated/clonidine). The effects of caffeine condition and drug condition wefi compared, at 3 time intervals, using analysis of covariance. Dkxssion: These outcomes suggest that increased turnover of central noradrenaline may explain at least some of the improvements in performance produced by caffeine in states of low arousal. However, at the cardiovascular level it appears that caffeine and clonidine influence separate mechanisms. Results: The same pattern of effects was observed across the test sessions on three well established measures of alertness, eye movement velocity, simple reaction time and subjective ratings. Clonidine was found to induce-a slowing of eye movement velocity, simple reaction time and a reduction in subjective alertness, whilst caffeine had the opposite effect. An interaction between drug and caffeine conditions demon- strated that the detrimental effects of donidine on perfor- mance were to some extent reversed by caffeine. In contrast blood pressure increased following caffeine and was lowered in the clonidine condition. These effects were independent of each other. 589 ELECTROEXPECTOGRAM: A TOOL FOR COGNI- TIVE PSYCHOPHYSIOLOGY L. Bozinovska*, T. Prevec** and S. Bozinovski**** Institute of Physiology, Medical Faculty, University of Skopje, Skopje, Macedonia, **University Institute? of Clinical Neuro- physiology, Medical Faculty, Ljubljana, Slovenia, * ** Electri- cal Engineering Faculty, University of Skopje, Skopje, Mace- donia .ji Our research is in the area of anticipatory brain potentials. The fact that they represent a process of expectation and/or preparation for some incoming event relates them to the cognitive processes in the brain. In our research we extended the CNV paradigm over many trials (between 60-1001 and plot a CNV parameter, usually CNV amplitude or slope. What we obtain is a curve showing rise and fall of the expectation (CNV parameter) over 100 trials. That curve we denote as Electroexpectogram or EXG curve. Symbolically EXG = f(p(CNVl,n), where p(CNV) is some CNV parameter, n is number of Sl-S2 trials, and f is a functional relation. A procedure in which the EXG is ob- tained is an EXG paradigm. We experimented with various EXG paradigms. The one which we explored mostly is the feedback based EXG paradigm. Let us note that we also use the term Dynamic CNV paradigm for this EXG paradigm. That is a paradigm in which the computer monitors the level of a CNV parameter (amplitude or slope) and when the parameter reaches some predelined threshold level (indicating presence of a CNV potential), the computer turns off the S2 signal. That causes CNV to extinct, which the computer recognizes and turns S2 on again. As result, an oscillatory cognitive process is visible in the human brain, showing oscillation of the CNV parameter over trials. The obtained curve is a represent of the subject state in the measured moment, and in analogy to EEG and ECG, we call it EXG. It is a new, electrophysiological tool, for cognitive neurophysiology. 590 RELATIONSHIP BETWEEN COGNITIVE SKILLS AND THE ELECTROEXPECTOGRAM L. Bozinovska* , J. Gligorovska* , S. Mancevska* , E. Sivevska* , S. Bozinovski* * *Institute of Physiology, Medical Faculty, **Electrical Engi- neering Faculty, University of Skopje, Macedonia An electrophysiological phenomenon, electroexpectogram (EXG), which develops in an expanded and modified CNV EXG is a result of oscillatory process of the expectancy paradigm, was analysed and compared with cognitive skills generated in the subjects minds during the EXG paradigm. The biofeedback based version of the EXG paradigm was psychological tests. This experimental research was carried used, in which the amplitude of CNV, reflecting expectancy of the subject in Sl-SZR paradigm, is a control parameter for out over 35 subjects. turning off and turning on S2 in the experiment. The examina- tion was carried out on two groups of children, one aged 9.27, the other 13.2. The electrophysiological measurements were: number of the cycles of EXG curve, their duration and amplitude. Psychological tests were: Pattern Classification Learning test and Kohs test of intelligence.