SOME OBSERVATIONS ON SPONTANEOUS OPTIC TRACT DISCHARGES IN FREE BEHAVING CATS

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Abstract
In cats carrying electrodes chronically implanted in the optic chiasm, spontaneous optic tract discharges (SOTD) were studied during natural sleep and under Nembutal anesthesia. The absolute strength of the SOTD and discharges of higher amplitudes than a certain level were sampled electronically (sampled SOTD) recording their rate. Nembutal suppressed the SOTD below the level maintained during natural sleep. Effects of steady retinal illumination upon the SOTD were examined. Under a nembutalized condition-the SOTD was mainly suppressed by retinal illumination. Retinal illumination caused an increase of the SOTD in non-anesthetized, sleeping cats. The SOTD often diminished when the animals entered from light to deep sleep. The SOTD usually fluctuated greatly during a maintenance of deep sleep and was difficult to correlate to fluctuation of other biological activities (systemic blood pressure, heart rate, and phasic body movements characteristics of deep sleep). Spontaneous synchronization of the SOTD at 1-4 c/s (pulsing) occurred during SOTD recovery usually in the transient phase between light and deep sleep. During maintained sleep, (light or deep) the SOTD decreased greatly temporarily. Recording the antidromic OT (optic tract) fiber responses under various strengths of the SOTD in different types of sleep, the antidromic responsiveness of the OT fiber terminals was determined according to the types of sleep, almost independently of tha strength of the background SOTD.