(A) Effects of PTV cooling on PSTHs of spike-responses of a class 2 complex area 19 cell to optimally oriented bar moving at different velocities. The stimulus was presented via the dominant (contralateral) eye. Stimulus size: 5° × 1°. (B) Velocity-tuning of peak spike-responses of the same cell whose responses are shown in (A). Note in (A,B) there is a substantial increase in the magnitude of responses during inactivation of PTV, especially for movement from left to right. (C) Preferred velocities of area 19 cells before inactivation vs. those during PTV inactivation (i) and control vs. rewarming (ii). In most cases, during cooling, inactivation resulted in upward shifts in preferred velocities. Note that the numbers indicate the number of data points that overlap. (Di) The direction selectivity indices (DSIs) of area 19 cells at stimulus velocities optimal before inactivation. In a large proportion of cells, inactivation resulted in large (≥20%) changes in their DSIs. Also in five cells (*) inactivation resulted in reversal of preferred directions of movements. # Denotes the response indicated by # in upper panel of (B). (Dii) DSIs at stimulus velocities optimal after PTV rewarming. @ Denotes the response indicated by @ in upper panel of (B). (Ei) The DSIs of a subpopulation of area 19 cells calculated at stimulus velocities optimal during cooling. Note in a majority of cells, inactivation resulted in large increases in their DSIs. (Eii) DSIs at stimulus velocities optimal during cooling in control condition vs. those after PTV rewarming.