Adaptation-induced plasticity of orientation tuning in a population of 72 neurons. (A) Scatter plot showing the amplitude of shifts in preferred orientation after adaptation as a function of the absolute difference between the control preferred orientation and the adapting orientation. Positive values (black dots) designate attractive shifts (n = 42) and negative values (grey dots) designate repulsive shifts (n = 30). The dashed lines in black and grey indicate the mean amplitude for attractive (17.3°) and repulsive (13.5°) shifts, respectively. (B) Scatter plot displaying the signal-to-noise (S/N) ratio of neuronal spikes' waveforms in the control condition as a function of the absolute shift amplitude (black dots indicate attractive shifts, whereas grey dots indicate repulsive shifts). Data are equally distributed around the S/N ratio mean values for both attractive (black dashed line) and repulsive shifts (grey dashed line). This distribution shows that shifts in orientation preference are unrelated to the S/N ratio (r < 0.1 regardless the direction of the shift). (C) Histograms showing the modulation of mean firing rate between control, adaptation and 60 minutes after adaptation conditions (error bars are SEM). Left: following the adaptation, a significant decrease of the firing rate is observed for the initial preferred orientation; paired sample two-tailed t-test, p < 0.001. Middle: in parallel, a significant increase of the response is observed for the newly acquired preferred orientation (attractive and repulsive shifts pooled together); paired sample two-tailed t-test, p < 0.01. Right: there are no significant changes in the response of far flank orientations (baseline); paired sample two-tailed t-test, p > 0.1. In all cases, recoveries are shown 60 minutes after the adaptation ended.