Kavli Affiliate: Joshua Berke
| Authors: Bon-Mi Gu and Joshua D. Berke
| Summary:
Suppressing actions is essential for flexible behavior. Multiple neural circuits involved in behavioral inhibition converge upon a key basal ganglia output nucleus, the substantia nigra pars reticulata (SNr). To examine how changes in basal ganglia output contribute to self-restraint, we recorded SNr neurons during a proactive behavioral inhibition task. Rats responded to Go! cues with rapid leftward or rightward movements, but also prepared to cancel one of these movement directions as a Stop! cue might occur. This action restraint – visible as direction-selective slowing of reaction times – altered both rates and patterns of SNr spiking. Overall firing rate was elevated before the Go! cue, and this effect was driven by a subpopulation of direction-selective SNr neurons. In neural state space, this corresponded to a shift away from the restrained movement. Furthermore, SNr activity showed an increase in spike variability during proactive inhibition, similar to that reported with movement slowing in Parkinson’s Disease. Increased spike variability corresponded to variable state-space trajectories, slowing reaction times via reduced preparation to move. These findings open new perspectives on basal ganglia mechanisms for movement preparation and cognitive control, in both healthy states and brain disorders.