Presynaptic inhibition and postsynaptic facilitation in lateral geniculate body and so-called deep sleep wave activity.

Abstract

Using cats carrying chronically implanted electrodes, impulse transmission in the lateral geniculate body (LGB) was studied under the influence of the deep sleep wave (DSW) activity described by Brooks and Bizzi. It was found that the DSW exerted the presynaptic inhibition and, simultaneoulsy, the postsyn-aptic facilitation upon the LGB response evoked by single shock stimulation of the optic tract (OT). This presynaptic inhibition was also confirmed by observing the antidromic OT response to stimulation of the OT terminals (Wall's method). The modification of the synaptic transmission was realized more strongly by a burst of DSWs than by a single isolated DSW. There ensued a similar phenome-non when single shock stimulation of the pontine reticular formation (PRF) yielded the DSW-like response in the LGB. Following the PRF stimulation, the postsynaptic component of the LGB response showed a marked decrease at about 30 msec, and then a summit of facilitation was reached at about 70 msec. The excitability change following this summit was variable. The presynaptic component was more or less suppressed with a similar time, indicating the presynaptic inhibition which could be evidenced more clearly by Walls' method.