D

FIGURE 6.2-1 Response sensitivity for a DS neuron located in the frog's superficial, contralateral tectum to a 2°-diameter black spot (dashed line) and a 4° x 1° black bar (solid line) moved across its RF in various directions. Scale: 2 cm = 40 spikes. A, anterior (0°); P, posterior (180°); D, dorsal (90°); V, ventral (270°). (Redrawn from Reddy, 1977.)

FIGURE 6.2-1 Response sensitivity for a DS neuron located in the frog's superficial, contralateral tectum to a 2°-diameter black spot (dashed line) and a 4° x 1° black bar (solid line) moved across its RF in various directions. Scale: 2 cm = 40 spikes. A, anterior (0°); P, posterior (180°); D, dorsal (90°); V, ventral (270°). (Redrawn from Reddy, 1977.)

At 4°/s, the response was less than for 1.1 °/s Figure 6.2-4 shows the vector response of a DS unit found in the frog's cerebellum. Reddy found that there was no correlation between RF location on the retina under test, and the preferred direction of some 34 DS units he measured. In fact, the distribution of preferred d d

FIGURE 6.2-2 Response sensitivity for a DS unit located in the frog's deep, contralateral tectum to motion of a 7°-diameter white spot (solid line) and a 2°-diameter black spot (dashed line) moved across its RF in various directions. Scale: 2 cm = 40 spikes. (Redrawn from Reddy, 1977.)

directions was apparently random, as shown in Figure 6.2-5. Reddy found several important differences between superficial and deep tectal DS units. The deep units had larger RFs (15 to 25°), and adapted quickly to repeated object movements. On the other hand, superficial tectal DS units had RFs from 4° to 12°, and showed no adaptation. Superficial tectal DS units also responded to smaller moving objects (2° to 6° diameter) than did deep units. The width of the response lobes was wider for superficial tectal DS units, and also tended to have larger side lobes. Deep tectal, thalamic, and cerebellar DS units in general had narrower response characteristics.

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