Changes in the Orthodromic and Anti- Dromic Response of Optic Tract during the Eye Movements of Sleep1

PREVIOUS STUDIES HAVE SHOWN that for each rapid eye movement of lowvoltage fast sleep there is a corresponding monophasic wave of 100-140 msec. in the lateral geniculate body of the cat (8). These waves do not depend upon the presence of the retina or the eye muscle afferents (5, 22). In fact, follow ,ing either retinal photocoagulation of the optic disc or enucleation of the eyes, these geniculate slow waves persist unmodified for 3 days, grow smaller in the next 3-5 days, and then disappear after the sixth day (5,22). Since the time course of wave disappearance correlates precisely with the time course of optic nerve degeneration following enucleation (25), it was suggested that optic tract terminals are involved in the genesis of lateral geniculate waves (5). The experiments to be reported here were designed to test whether impulses going through the op tic tract terminals and the lateral geniculate were modified as a consequence of changes taking place in the presynaptic terminals of the optic tract during the slow geniculate waves and the related eye movements. The findings indicate that depolarization of optic tract terminals and depression of transmission through the lateral geniculate occur during the appearance of these waves.