Rapid Eye Movements Elicited By Luminance And Stereo Stimuli

Saccades, as rapid eye movements, are usually elicited by position information.Therefore, it would be a rational assumption to explore the visual processing andmotor programming in saccades with different types of signal of position invasively.In the first part of this thesis, saccadic responses elicited by luminance (luminancecontrast defined, first-order) and stereo (binocular disparity defined, third-order)stimuli were compared, and their changes after the administration of CNS drugs(Benzodiazepines, Bzs) were examined. Experimental results showed that thesaccadic latency for stereo stimuli was significantly greater than that for luminancestimuli;however, the relationship between peak velocity and amplitude of saccadesfor stereo stimuli was similar to that for luminance stimuli. Although Bzadministration prolonged the latency of saccades for stereo and luminance stimuli, thepercentage increases in saccadic latency for stereo stimuli were significantly largerthan those for luminance stimuli. Saccadic peak velocity and amplitude alsosignificantly decreased after Bzs under conditions of stereo and luminance stimuli.However, there was no significant difference for either saccadic peak velocity oramplitude between the two stimulus conditions. The results indicated that thedifferences between two types of saccades were determined by the visual processing,with a greater involvement of cortical areas in saccades to stereo stimuli compared toluminance stimuli. In contrast, the motor programming of saccades was similar underthe two stimulus conditions. In the second part, we studied the effect of Bzs oninvoluntary rapid eye movements, the fast phases of optokinetic nystagmus (OKN),and explored the control properties of OKN fast phases under closed-and open-loopstimulus conditions. After Bz administration, the peak velocity and amplitude of OKNfast phases were significantly decreased, and the relationship between peak velocityand amplitude were impaired. Thus, the saccades to the stereo stimuli could provide anew approach to evaluate the pharmacodynamic effects of Bzs on the cortical areas,and the OKN fast phase demonstrated an objective method to access the effects of Bzson the brainstem areas.