Velocity-tuning of motion-sensitive and direction-selective cells in the rabbit striate cortex.

The receptive field characteristics of 268 striate cortical cells were classified in 10 Dutch-belted rabbits. From the 66 motion-sensitive and direction-selective units encountered, quantitative data describing the responses of 41 motion-sensitive, and 10 direction-selective cells to moving gratings were obtained. The results showed that all cells responded with increased spike discharges to increased velocities of the moving gratings up to a maximum, then they became less responsive to further increase of the velocities. The patterns of the response curves varied from cell to cell. When the 51 cells were taken as a whole, there were more cells responding to the velocities of 10-30 deg/sec than to higher or lower velocities. The total range over which these cells responded was 0.1-300 deg/sec. The preferred velocities for individual cells ranged from 1.5 to 150 deg/sec, showing a moderate concentration at the 6-40 deg/sec region. The extent of the effective velocities for individual cells formed a continuous distribution. No segregation into groups was seen in either of the two cell types studied or in all cells taken as a group. These data were compared with those reported for the rabbit retinal ganglion cells and the cells in the nucleus of the optic tract, as well as the cells in the cat visual system.