The External Globus Pallidus is a Major Basal Ganglia Output Hub with Action-Specific Circuits [SMART-seq]

Using whole-brain projection mapping, single-neuron reconstruction, transcriptomics, rabies tracing, and closed-loop optogenetics, we show that the GPe is itself a major modular output structure, organized into parallel channels that selectively control distinct actions.

Projection-defined GPe populations directly target thalamic and brainstem motor centers and exhibit action-specific dynamics and functions. GPe→PPN neurons are selectively suppressed during locomotion, and their manipulation bidirectionally controls locomotion. Critically, D2-SPN activation promotes locomotion through disinhibition of this pathway, revealing a direct movement-facilitating route stemming from D2-SPNs.