Abstract
The effect of single shock stimulation of the mesencephalic reticular formation upon the geniculate evoked potential and the response probability of optic radiation units to optic tract stimulation was studied in locally anesthetized and curarized cats.
1. The geniculate evoked potential following optic tract stimulation consisted of two components, i. e. the pre-and postsynaptic components respectively. By conditioning stimulation of the mesencephalic reticular formation the postsynaptic component alone was augmented for a few hundred msec. without significant alteration of the presynaptic one.
2. Remarkable facilitatory effects were obtainable only when a certain limited region of the mesencephalon was stimulated.
3. Discharges of single radiation units were explored, and it was found that they received facilitatory and/or inhibitory effects following reticular stimulation, the facilitatory effect being predominant in most units. These effects were manifested as changes in responsiveness of radiation units to liminal optic tract stimuli after conditioning reticular stimulation.
4. From the result mentioned above it was concluded that transmission at most geniculate synapses was facilitated following reticular stimulation.
