Activity of fast?spiking interneurons in the monkey striatum during reaching movements guided by external cues or by a free choice

Parvalbumin-containing GABAergic interneurons in the striatum, electrophysiologically identified as fast-spiking (FSIs), exert inhibitory control over striatal output to drive appropriate behavior. While a number of studies have emphasized their importance motor control, it is unknown how these putative adapt functional properties different modes movement selection. Here, we tested whether FSIs are sensitive externally versus internally selected movements by recording activity while two male rhesus monkeys performed reaching visual targets. Two variants were used: an external condition, which instructed via cues, and internal guided representation target location. These conditions allowed contrast FSI associated with either cued or driven After extensive training, performance was only marginally affected type movement, albeit some differences between monkeys. Over two-thirds modulated around onset, regardless consisting mostly increased activity. We found that subset showed stronger activation related initiation condition than suggesting dependence on selection mode. Moreover, this difference strength predominant striatum. data indicate changes carry information scaled constraints action reflecting involvement local circuits adaptation behavior according task demands.