Song decorrelates cortico–basal ganglia ensembles in zebra finches

The ability to acquire and adjust a sensorimotor skill relies on coordinated activity within a cortico–basal ganglia–thalamo–cortical loop, yet the underlying inter-areal dynamics remain unclear. The zebra finch ( Taeniopygia castanotis ) is well suited for studying these mechanisms, as male song depends on this circuit to bias downstream motor activity and adjust vocal output to social context. Using a custom-made reusable and torque-adjustable Neuropixels implant, we simultaneously recorded neural activity in the premotor region LMAN and in the basal ganglia–like striatal region Area X during rest, solo song, and female-directed song. Pairwise cross-covariance analyses among LMAN units and established striatal and pallidal neuron types revealed heterogeneous interactions during song that vanished on a population level whereas strong co-activation emerged for non-singing epochs. These results suggest that cortico–basal ganglia interactions are dynamically regulated across behavioral states—strong during spontaneous activity yet decorrelated during song—without specialization by Area X neuron type.