Journal of Neurophysiology, Vol 40, Issue 1 9-15, Copyright © 1977 by APS
Antidromic activity in visual radiation during evoked cortical responses
A. D. Rosen and E. F. Vastola
1. Antidromic stimulation of the visual radiation of cats has been used to
investigate the possibility that some of the activity in principal
geniculate cells following an optic tract stimulus is antidromic. Single
spikes were selected from two classes of poststimulus activity to condition
the antidromic test spike--the undoubted orthodromic postsynaptic spike and
the later spikes, occurring up to 100 ms after the optic tract stimulus. 2.
In 15 of 39 cells the minimum antidromic activation times and the minimum
spike-spike intervals were found to be shorter and latencies for antidromic
stimulation were longer when the conditioning spikes belonged the class of
late poststimulus activity. The differences are in accord with the
assumption that some of the conditioning spikes were antidromic. 3. Test
spikes were frequently found to have long and variable latency when the
conditioning spike occurred more than 45 ms after the optic tract stimulus.
Possible reasons are briefly discussed. 4. It is suggested that antidromic
activity may occur in conditions of the cortex that are more physiological
than those associated with a penicillin-induced seizure focus. Some
possible mechanisms and functional significance are briefly discussed.
