Target-Cell-Type Specificity of Corticostriatal Pathways in Movement Control

The striatal direct and indirect pathways exhibit overlapping yet distinct functions in movement planning and control. However, it remains unclear how those distinct functions arise. We investigated an input structure to the striatum, the secondary motor cortex (M2), to find whether this input can potentially drive the functional heterogeneity of direct and indirect pathways in skilled and innate movements. Here, we used monosynaptic retrograde viral labeling, two photon imaging and perturbation experiments to investigate the activity correlation between direct/indirect medium spiny neurons (MSNs) in the dorsal lateral striatum (DLS) and their target cell-type-specific projecting neurons in M2. We found that activity patterns of projecting neurons in M2 do not appear to be overlapping with the activity patterns observed in MSNs in DLS. In addition, perturbations in parafascicular nucleus (PF) led to the abolishment of MSN activities in DLS, while M2 perturbations only decreased MSN activities. Therefore, we proposed that the functional heterogeneity of direct and indirect MSNs in movement control is not likely to be differentiated in M2, and there is a possibility that this heterogeneity can be differentiated in PF.