Projections between the globus pallidus externa and cortex span motor and non-motor regions.

The globus pallidus externa (GPe) is a heterogenous nucleus of the basal ganglia, with intricate connections to other basal ganglia nuclei, as well as direct connections to the cortex. The anatomic, molecular and electrophysiologic properties of cortex-projecting pallidocortical neurons are not well characterized. Here we show that pallidocortical neurons project to diverse motor and non-motor cortical regions, are organized topographically in the GPe, and segregate into two distinct electrophysiological and molecular phenotypes. In addition, we find that the GPe receives direct synaptic input back from deep layers of diverse motor and non-motor cortical regions, some of which form reciprocal connections onto pallidocortical neurons. These results demonstrate the existence of a fast, closed-loop circuit between the GPe and the cortex which is ideally positioned to integrate information about behavioral goals, internal states, and environmental cues to rapidly modulate behavior.