Figure 1.

Recording neural activity in the RN. A, Illustration of a head-fixed rat pup in the recording apparatus. B, Reconstruction of electrode placements (blue vertical lines) within the RN in three successive coronal sections for all pups in the study (N = 8). C, Left, Coronal brain section stained with cresyl violet. Red vertical line is the trace of the DiI-coated electrode positioned through the RN. Middle, Representative recordings of MUA in the RN from three successive electrode sites (top traces) and EMG recordings from the contralateral forelimb (bottom trace). The unit activity contained within the dashed box is magnified at right to reveal a burst of action potentials with ISIs ≤8 ms, defined here as a complex spike. PAG, Periaqueductal gray; 3N, oculomotor nucleus; IV, fourth ventricle; M, medial; V, ventral.