Figure 6.

Examples of receptive fields encountered during two electrode penetrations of MT in an animal lesioned at 6 weeks of age (W6C). A, Receptive fields of neurons in caudal MT form a topographic sequence across the V1 scotoma (1–10). The ovals in the left diagram represent the best-fitting ellipses of the quantitatively mapped receptive fields (displayed in the “receptive field” column). The rectangles represent receptive fields mapped by hand-operated stimuli. The corresponding recording sites, shown in a coronal section, are identified by numbers (1–10) and color-coded. The histological borders of MT, identified by dense myelination, are indicated by dashed lines in the bottom diagram. The corresponding receptive field maps and direction tuning curves (tested with dot fields) are shown on the middle column. B, Receptive fields of neurons in rostral MT, forming a sequence across the visual field peripheral to the V1 scotoma (a–f). Other conventions as in Figure 5 B and C. L, Lateral; D, dorsal; HM, horizontal meridian; VM, vertical meridian. The size of the square stimulus used for mapping receptive fields 4–10 was 4°, 3°, 3°, 3°, 2.5°, 2.5°, and 2.5° respectively. Maximal firing rates were 77.7, 20.7, 67.6, 20.2, 57.1, 36.6, and 24.5 Hz, respectively. Maximal firing rates of the direction tuning curves are displayed under the polar plots.