Localizing recording sites to ZII stripes in the ventral uvula. A and B show photomicrographs of a coronal section through the caudal region of folium IXcd. In A (B), an injection of red (green) CTB is shown with ZII+ labeling in green (red). The thin dashed lines denote the electrode tracks, whereas the thick dashed lines indicate the midline. The inverted triangles indicate the ZII-immunonegative notch separating the medial and lateral portions of P2+ (P2+med, P2+ lat). In A, an expansion cell was recorded at the injection site, located in P2+med. In B, a descent cell was recorded at the injection site in P2+lat. In the rightmost track, located 600 μm medial to the injection track, an ascent cell was recorded as indicated (*) in the lateral portion of the P1− stripe (P1−lat). C shows a drawing of coronal section through folia IXcd and X with ZII+ and ZII− stripes indicated, respectively, by red and white shading in the molecular layer. Multiple parallel electrode penetrations are represented by thin dashed lines. The medial-most injection from the oblique electrode penetration (green CTB) was easily distinguished from the lateral-most injection from the vertical electrode penetration (red CTB), and was used as the reference point for reconstructing the remaining oblique electrode penetrations, which were based on stereotaxic coordinates. The orange, purple, and light blue asterisks indicated locations where descent, expansion, and contraction cells were recorded, respectively. At the half-green/half-purple asterisk on the lateral edge of P1−lat, both ascent and expansion units were recorded at the same location. (The two units were separated with spike sorting.) The two shaded gray areas indicate the locations of two injection sites. Representative direction tuning curves are shown for each type of neuron. Firing rate is plotted as a function of direction of motion in polar coordinates. The gray circles represent the spontaneous rates. Scale bars: A, B, 300 μm; C, 250 μm. U, D, R, L, Upward, downward, rightward, and leftward motion.