Figure 2.

Npy2r-Cre mice capture a mixed population of GPe neurons. a, Npy2r-L-tdTomato mice labeled neurons in the GPe and striosomes in the dStr (top). Inset, Magnified view of a striosome. Prominent axons were apparent in the STN (middle) and SNc and SNr (bottom). b, Axonal projection patterns from Npy2r⁺ neurons are similar to that of Npas1⁺-Nkx2.1⁺ neurons and Npr3⁺ neurons. Only a low density of axons was observed in the STN and SNr. Bottom right, ChR2-eYFP⁺ neurons were largely Npas1⁺. c, Top left, tdTomato-expressing (PV⁺-Npy2r⁺) neurons were observed throughout the GPe in PV-Npy2r-FL-tdTomato mice. PV⁺-Npy2r⁺ neurons were immunoreactive for Nkx2.1 (top right) but not for Npas1 (middle right). Bottom, Most of PV⁺-Npy2r⁺ (tdTomato⁺) neurons were PV⁺. PV⁺-Npy2r^– (green) neurons were visible in the same field (arrowheads). White circles represent colocalization. d, Composite confocal micrograph showing a typical biocytin-filled PV⁺-Npy2r⁺ neuron. In addition to the main axon, local collaterals were observed. cc, Corpus callosum; MO, motor cortex; SubB, subbrachial nucleus; ZI, zona incerta.