(Ai) PSTHs of spike-responses of an area 19 complex, class 2 cell, illustrating the influence of cooling of PTV on peak spike-responses to moving stimuli of two different orientations. Note that during PTV inactivation the cell exhibited substantial decrease in its peak responses to stimuli moving along the axis of one orientation (20°–200°) and a substantial increase in its peak responses to stimuli of another orientation (60°–240°). Stimulus size: 10° × 0.6°. (Aii) Effects of PTV cooling on orientation-tuning property of the same cell shown in (Ai). Note during cooling, there was a 40° shift in optimal orientation but only in the non-preferred direction of movements. The shift was accompanied by an increase in orientation-tuning width at half-height (WHH). Thirty minutes after PTV was rewarmed, the responses and optimal orientation recovered to the pre-cooling levels. (B) Optimal orientations prior to cooling vs. those during cooling(i—preferred direction, ii—non-preferred direction) or after rewarming of PTV (iii—preferred direction, iv—non-preferred direction). In the insert frequency histogram within (Bi), cells exhibiting large (≥20°) shifts in optimal orientation during inactivation of PTV are represented. Note that the numbers indicate the number of data points that overlap. (C) The widths of orientation-tuning curves at half-height calculated from the control condition vs. those during PTV cooling (i) and control condition vs. those after PTV rewarming (ii) * in (Ci) and (Cii) indicate a cell whose responses are illustrated in (Ai) and (Aii). A-pr and A-npr refer to responses of cell in panel (A) at preferred and non-preferred directions respectively. Note the same cell is represented twice. The responses in non-preferred direction is indicated by * -npr.