Abstract
The STN provides glutamatergic projections to both pallidal segments and SN. In these experiments we examined the prevalence of excitatory and inhibitory responses to STN stimulation in the primate SN, and mapped the topography of these responses by systematically changing the stimulation location in the STN. Two monkeys received chronic recording chambers directed at STN and SN. One chamber was used to carry out electrical stimulation of the STN with a microelectrode (monophasic stimulation at 1/s, pulse width 50 μs, amplitude < 300 μA), and the other to simultaneously record the neuronal activity in SN, using standard extracellular single-unit recording techniques. Peristimulus histograms were used to evaluate responses to stimulation. Excitatory responses were scattered in a broad area of the SN when the stimulation electrode was in the medial part of the STN. However, responses were confined to portions of the SN when the stimulation electrode was in the lateral part of the STN. Same tendency was found for inhibitory responses. The results suggest that total output of the SN evoked by stimulation changes significantly depending on the stimulation location in the STN. [Jpn J Physiol 55 Suppl:S177 (2005)]
