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Neural Correlates of Vasarely's Nested Squares and the Alternating Brightness Star Illusion in area V1

56.406, Tuesday, May 14, 2:45 - 6:45 pm, Orchid Ballroom
Session: Color and light: Lightness and brightness

Jie Cui¹, Stephen Macknik¹, Xoana Troncoso^1,2, Jorge Otero-Millan¹, Susana Martinez-Conde¹; ¹Barrow Neurological Institute, Phoenix, AZ 85013, USA, ²Unite de Neuroscience, Information et Complexite, (CNRS-UNIC), UPR CNRS 3293, Gif-sur-Yvette, France

Vasarely's 'nested-squares' illusion shows that 90° corners are more salient perceptually than straight edges. On the basis of this illusion we developed previously the 'Alternating Brightness StarÂ’ illusion, which shows that sharp corners are more salient than shallow corners, and that the same corner can be perceived as either bright or dark depending on the polarity of the angle (i.e. whether concave or convex) (Troncoso, et al, 2005, 2009). Here we presented these illusions to awake monkeys while we recorded from single neurons in area V1, during guided-viewing conditions. Neuronal responses, calculated via eye-position corrected reverse correlation, concentrated on the illusory "folds" from luminance gradients composed of aligned corners, in agreement with previous psychophysical results. Sharp corners generated higher firing rates than shallow corners, irrespective of angle polarity, also consistent with human perception. These data support the hypothesis that corner and junction processing starts in the earliest neural stages of the visual hierarchy.

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