Analysis of the brain regions involved in myoclonus produced by intracerebral picrotoxin.

Picrotoxin caused myoclonic jerking of the opposite forelimb when applied to the striatum and the cortical surface of rat brain. Intrastriatal picrotoxin increased [3H]2-deoxyglucose uptake by the ipsilateral frontal cortex, thalamus and subthalamic nucleus. Electrolyte and ibotenic acid lesions made in the globus pallidus prevented striatally evoked myoclonus without affecting the movements elicited from the cortex. Electrolytic lesions in the subthalamic nucleus and thalamus affected striatally evoked myoclonus more than the cortically elicited response. It is concluded that striato-pallidal-thalamic-cortical circuitry is responsible for striatally evoked myoclonus.