Figure 1. Identification of Purkinje and CbN cells involved in hindlimb movement during locomotion.

(A) Top, Schematic of the setup including a head-fixed mouse running on the cylindrical treadmill, with paw movement recorded with an infrared camera. The patch pipette contained an electrode wire and an optical fiber. Bottom. Side-view of the ipsilateral hindlimb (left). A cursor (green cross) tracked the X and Y positions of tip of the paw within a marked ROI (green box). The paw record (right) was captured at ~ 240 frames/s. (B) Left, AAV2/9-mediated retrograde labeling of Purkinje inputs following injection of a viral mixture (ChR2-mCherry and ChR2-eYFP) in the interpositus nucleus of Pcp2-cre mice. Sample image of a coronal section showing an overlap (white) of mCherry (magenta) and eYFP (green) label in Purkinje cells of lobulus simplex. sim, simplex, prf, primary fissure, IA, interpositus anterior, IP, interpositus posterior, IDL, interpositus dorsolateral hump, Lat, lateral nucleus, Me, medial nucleus. Upper right, higher magnification image of labeled Purkinje somata (arrows) at the bottom of lobulus simplex surrounding the primary fissure. Lower right, higher magnification image of the site of injection in the nucleus interpositus posterior, showing labeled terminals of Purkinje afferents, but not CbN cell bodies. (C) and (D), Left, Sample images of coronal sections from two different mice. Green, Alexa 488-dextran amine injected at two sites along the recording track in mice expressing ChR2 and tdTomato (magenta) in all Purkinje cells (Ai27D x Pcp2-cre). Dotted arrows, injection pipette track. (D), right. Higher magnification images of the labeled Purkinje somata (top; arrows) and CbN cell somata (bottom) along the track in D.