The blockage of ponto-geniculo-occipital waves in the cat lateral geniculate nucleus by nicotinic antagonists.

The cholinergic mechanism underlying the genesis of ponto-geniculo-occipital (PGO) waves recorded from the lateral geniculate (LG) nucleus was studied in reserpinized cats under urethane anesthesia. PGO field potentials and their related unit activities occurred spontaneously or were triggered by stimulation of the brainstem peribrachial (PB) area. It was found that PGO-related unit activities were strongly depressed by systemic or iontophoretic applications of nicotinic antagonists such as mecamylamine or hexamethonium but remained intact after similar applications of scopolamine. These results suggest that the genesis of thalamic PGO waves involves a nicotinic activation of relay neurons by PB cholinergic afferents.