Figure 4A plots the response of a unit as a function of the translating RDPs position relative to the estimated RF center (see Figure 3A).

The positions of the translating RDPs (here moving in the Pr direction) are projected onto a virtual axis connecting the fixation point with the RF selleck center. The upper two panels contain raster plots of the individual spikes in “outward” and “inward” trials (see Figure 1A), and the lower two panels show the corresponding spike density functions (SDFs). In both trial types, the cell responded vigorously to the onset of the three stimuli (response on both left and right abscissa limits). This response was likely evoked by the RF pattern since the translating RDPs were positioned outside the RF. Immediately after, the response rapidly decreased and then remained relatively constant as the translating RDPs approached the RF center. Interestingly, during attend-RF (green) responses were considerably PI3K inhibitor stronger than during tracking (red). When the translating RDPs’ local dots moved in the AP direction (Figure 4B), the responses during tracking also initially increased and then continuously decreased to reach a minimum at approximately the RF center.

Again, during the attend-RF condition responses were considerably stronger. Interestingly, the differences in response grew larger relative to Figure 4A. Thus, tracking decreased the responses of this unit relative to attend-RF, mainly when the translating RDPs were close to the RF center. This effect

was stronger when the translating RDPs local dots moved in the AP direction. We quantified these observations across all neurons by computing for each unit a modulation index (MI) between responses in both conditions (see Experimental Procedures). Positive MIs indicate higher firing rates during tracking relative to attend-RF and negative the opposite. Figure 4C shows the MIs 17-DMAG (Alvespimycin) HCl for all neurons as a function of the translating RDPs position relative to the RF center when their dots locally moved in the Pr (top) and AP (middle) directions. Neurons were sorted according to their RF size (thick lines) and aligned to the RF center. Each RF was divided into three regions of equal size (thin black lines). To estimate the MIs along the translating RDPs trajectory these regions were extended outside the RF. For translating RDPs’ with dots locally moving in the Pr direction (top) most neurons showed weaker responses during tracking than during attend-RF, with a largest difference at the RF center (blue). When dots locally moved in the AP direction (middle panel) the results were similar but the response differences were even stronger, particularly at the RF center.