Response modulation across conditions.

<p>A: Histograms show the mean firing rate for 2 particular orientations; the new preferred acquired orientation following adaptations and the baseline level (flank orientations). Adaptation I increases the firing rate at the new preferred orientation (<i>t</i>-test, p<0.0001). In parallel, the mean response decrease at the control preferred orientation (see insert histogram in B, <i>t</i>-test, p<0.0001). The firing returns to its control values within 60–90 min (<i>t</i>-test, p>0.1). Adaptation II enhances further the firing rate of 20% over the first one (<i>t</i>-test, p<0.001). Baseline remains unchanged across conditions (<i>t</i>-test, p>0.1). B: Scatter plots showing <i>on a cell by cell basis the</i> modulation of responses at the new preferred stimulus. Data of spike counts were transformed into logarithmic values. Left column: the cells' responses increase after adaptation I (blue circles, r = 0.68) and returned near to control values (green crosses, r = 0.76). Right column: following adaptation II, the cells' responses increase comparing to the first one (red crosses, r = 0.83). Dashed lines indicate the 95% confidence intervals. Correlation coefficients are different between adaptation I and II (Z_D = 2.57, p<0.005).