Synchrony level in relation to the preferred orientation difference in neuron pairs prior to adaptation. (A) Schematic example of raw tuning curves showing the data points (broken lines) for which the synchrony was measured. In this example the preferred orientation difference is 22.5°. CCHs were computed for the initial preferred orientation of each cell and for the adapting orientation. (B) Example of cross-correlation histogram (CCH) where cells had identical preferred orientation (0°). Synchrony index (SI) measured at 0 time lag, SI value was 0.041. Confidence intervals at 99.9% levels are indicated by green lines. (C) Example of CCH where the preferred orientation difference is 45°. In that case, the SI is lower (0.027). (D) Example of CCH where the difference extends to 90° (rare in our sample). The height of the central peak is clearly not significant being below the upper confidence interval, and the SI value was 0.004. Orientation differences from curves fits measurements was 4.0°, 40.0° and 84.1° in B, C and D, respectively. Pairs comprising neurons with distinct preferred orientations (e.g. in C and D) produced 2 CCHs, only one is shown for sake of clarity.