eLife assessment
This study reports valuable findings that corticostriatal projections (specifically, from M1 and MCC ) target direct and indirect pathway striatal projection neurons in partially segregated ways. Moreover, this partial segregation is biased, implying that specific engagement of the direct pathway may be achieved through the selective activation of unique cortical neurons. The evidence for this conclusion is solid, though the key experiments (rabies tracing controls, etc.) are incomplete. Otherwise, the experiments are rigorously designed, and the results are solid. This work will be of interest to those interested in brain anatomy and/or circuitry, cortical and/or basal ganglia function, locomotor activity, reinforcement learning, or diseases related to these.