Figure 1.

Identification of D₁ and D₂ MSNs. a, A sagittal slice taken from a P40 FVB mouse. Ctx, Cortex; Cpu, caudate putamen; GP, globus pallidus; ec, external capsule; ic, internal capsule. b, Confocal image of eGFP-positive MSNs from a BAC transgenic animal. c, Visualized whole-cell recordings were made with contrast-enhanced IR-DIC microscopy (see Materials and Methods). d, Single-cell RT-PCR (scRT-PCR) verification of substance P (sp) and enkephalin (enk) expression in D₁ and D₂ spiny neurons. e, f, Injection of Cholera toxin subunit B-Alexa 647 into the SNr of BAC D₁ and D₂-eGFP mice displays overlapping and mutually exclusive populations of MSNs.