The experiments described in this application are intended to provide pilot data concerning the effects of local pharmacological manipulations of basal ganglia (BG) output neurons (in particular, GABAergic substantia nigra pars reticulata (SNr) neurons) on jaw movements, jaw muscle EMG activity and trigeminal sensory- motor reflex activity in chronically prepared awake cats. In these experiments, chronic cannulae implanted in the SNr will allow the local injection of GABA agonists or antagonists into the SNr so that we can observe the effects of increasing or decreasing GABAergic SN outputs on oral sensory and motor behavior. Also, since pharmacological manipulations of the the BG (with dopamine receptor blocking drugs) are a prime cause of abnormal involuntary oral movements (i.e., tardive dyskinesia), the second experiment in this proposal is designed to obtain pilot data concerning the effects of chronic neuroleptic drug administration of trigeminal main sensory and motor neuron responses to afferent inputs and to microiontophoretically applied putative neurotransmitter substances. These studies will use standard acute extracellular electrophysiological techniques. It is anticipated that data from these pilot studies will guide us in assessing the usefulness of the proposed experimental approaches and in designing studies which will hopefully lead to a better understanding of BG-trigeminal interactions.
