Fig. 4: Stimulus-stimulus interactions in retinal “saccadic suppression”.
a Example RGC responding only weakly to texture displacements (top), but nevertheless exhibiting strong suppression of flash-induced responses (bottom; curves plotted at the same scale). Asterisks indicate significantly suppressed flash-induced responses (p < 0.0001, one-tailed sign test, N = 39 independent observations; Methods). Exact p-values at each flash time: 117 ms (p = 10−5), 150 ms (10−5), 200 ms (10−6), 350 ms (10−5), and 600 ms (0.26). b Population modulation index (mean ± s.e.m., N = 31 RGCs) when the textures jumped from their start to end positions instantaneously. Strong suppression (*p < 0.01, two-tailed Wilcoxon signed-rank test) and significant differences between coarse (red) and fine (blue) textures (#p < 0.0001, two-tailed Wilcoxon signed-rank test) still occurred. Exact p-values at each flash time (coarse, fine, across): 17 ms (p = 10−6, p = 0.027, p = 10−6), 50 ms (10−6, 0.021, 10−6), 100 ms (10−5, 0.001, 10−6), 250 ms (10−6, 0.001, 10−4), and 500 ms (0.002, 0.04, 0.06). c Two example RGCs showing that a flash before saccade-like texture displacements suppressed the response to the displacements, suggesting that stimulus–stimulus interactions drive retinal “saccadic suppression”. d Population modulation index (mean ± s.e.m., N = 376 RGCs) for a paradigm similar to b, but with textures replaced by spatially uniform backgrounds of different intensity (i.e., instantaneous luminance steps). Suppression of flash-induced responses was preserved (*p < 10−10, two-tailed Wilcoxon signed-rank test), and differences between low-contrast (light gray) and high-contrast (dark gray) luminance steps (#p < 10−10, two-tailed Wilcoxon signed-rank test) resembled the differences between fine and coarse texture jumps in b. Exact p-values at each flash time (high contrast, low contrast, across contrasts): 17 ms (p = 10−48, p = 10−32, p = 10−43), 33 ms (10−55, 10−41, 10−48), 50 ms (10−60, 10−46, 10−51), 100 ms (10−57, 10−50, 10−42), 250 ms (10−39, 10−33, 10−26), 500 ms (10−8, 0.02, 10−8) and 1000 ms (0.9, 0.7, 0.8). e Overlaid modulation profiles from texture displacements (Fig. 3e), texture jumps (b), and contrast steps (d). Coarse texture displacements, coarse texture jumps, and high-contrast luminance steps had similar effects; and so did fine texture displacements, fine texture jumps, and low-contrast luminance steps.
