Modification of saccadic eye movements by GABA-related substances. II. Effects of muscimol in monkey substantia nigra pars reticulata.

摘要: The preceding study (21) showed that a gamma-aminobutyric acid (GABA) agonist or antagonist injected into the superior colliculus (SC) disrupted saccadic eye movements. purpose of present experiments was to determine whether this result due altering inhibitory input SC from substantia nigra pars reticulata (SNr). SNr cells are themselves inhibited by GABA. Injection muscimol, GABA agonist, should increase inhibition acting on and reduce SC. If effects in results terminals originating SNr, muscimol act like bicuculline Muscimol has same general effect as monkey made irrepressible saccades toward contralateral visual field where at injection site had their movement field. During fixation jerks occurred, interspersed with spontaneous saccades, instead targets remembered targets. Saccades were more vulnerable these intrusions than Since acts SC, we conclude substantial fraction GABA-mediated inputs originates SNr. These experiments, conjunction previous show exerts tonic saccade-related is mediated role initiation particularly important since severely well We suggest both conclusions about might apply skeletal movements well. First, basal ganglia contribute release target structure inhibition. Second, mechanism critical based stored signals not currently available incoming sensory inputs.