Quantitative assessment of RF properties was based on the analysis of responses to stimuli presented via the dominant eye. To prevent cell habituation (or adaptation), a delay of 800 ms was introduced when the stimulus velocity exceeded 6.6°/s. In all runs in which the stimulus velocity did not exceed 33°/s, the bin width was 22 ms. In runs in which the stimulus velocity was higher, the bin width was 6 ms. Thus, the same number of spikes per bin at velocities ≥46.2°/s (bin width 6 ms) and at velocities ≤33°/s (bin width 22 ms) do not indicate the same or similar number of spikes/s. Optimally oriented visual stimuli were usually traveling at its preferred velocity across the RF in the direction orthogonal to its optimum orientation. Peri-stimulus time histograms (PSTHs) were constructed from a sum of 5 or 10 repeats for each test condition. A Gaussian weighted average over five neighboring bins of PSTHs were then applied to smooth the responses. Peak response rates and mean background activity were determined at each condition, tuning curves as well as widths at half-height (WHH, see Figure 3Aii) were calculated.