Abstract
1. In cats carrying electrodes chronically implanted in the optic chiasm, some properties of spontaneous optic tract discharges (SOTD) were studied during natural sleep and under Nembutal anesthesia. In addition to a direct measurement of the absolute strength of the SOTD, discharges which had higher amplitudes than a certain level were (sampled electronically sampled SOTD) and their rate was counted.
2. Nembutal suppressed the SOTD below the level maintained during natural sleep.
3. Effects of steady retinal illumination upon the SOTD were examined. The finding of previous workers was confirmed that under a nembutalized condition the SOTD was mainly suppressed by retinal illumination. On the other hand it was revealed that retinal illumination caused a more or less increase of the SOTD in non-anesthetized, sleeping cats.
4. The SOTD was often found to diminish when the animals entered from light sleep to deep one.
5. The SOTD usually fluctuated greatly during a maintenance of deep sleep. This fluctuation of the SOTD was found difficult to be correlated to fluctuation of other biological activities such as the systemic blood pressure, the heart rate and the phasic body movements characteristics of deep sleep.
6. Spontaneous synchronization of the SOTD at 1-4 c/s (pulsing) was seen to occur when the once decreased SOTD was progressively attaining its original strength. This occurred usually in the transient phase between light sleep and deep one. It could also be seen during maintained sleep, either of light type or deep one, after the SOTD suffered temporarily a great reduction.
7. Recording the antidromic OT fiber responses under various strengths of the SOTD in different types of sleep, it was found that the antidromic responsiveness of the OT fiber terminals is determined according to the types of sleep, almost independently of the strength of the background SOTD.
