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Dave Ellemberg, Olivier Brault, Myriame Masson; Electrophysiological correlates of suppressive lateral interactions. Journal of Vision 2015;15(12):109. doi: https://doi.org/10.1167/15.12.109.
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© ARVO (1962-2015); The Authors (2016-present)
The visibility of image elements can be reduced by other elements in their vicinity. This is usually explained by inhibitory lateral interactions among neurons in the primary visual cortex, although there is little evidence for the involvement of intracortical inhibition. Further, the mechanisms underlying these interactions remain unknown. We investigated the neural bases of suppressive lateral interactions by recording visual evoked potentials together with psychophysical measures for visual targets in the presence of flanking stimuli. High-density EEG’s were recorded in eight observers with normal or corrected-to-normal vision in response to a foveally viewed Gabor as a function of the spacing of horizontally adjacent Gabors. Inter-element spacing ranged from 1.5 to 6 cycles from the centre of the target to the centre of either of its adjacent flankers. The central target had the same or a different orientation (0 º, ±15º, ±30º, and ±60º) and spatial frequency as the flankers (0, ±.5, and ±1 octave). Each stimulus configuration was repeated 80 times and stimuli were interleaved. We analyzed the power density and spectral coherence over the time-frequency plane (in the central occipito-parietal region). Power density (p = 0.015) as well as short- (p = 0.005) and long-range (p = 0.005) spectral coherence decreases as inter-element spacing decreased to reach conditions under which the psychophysical test produced the greatest suppression in the apparent contrast of the central Gabor. A similar pattern of results was found when the spatial frequency and orientation of the flankers were systematically varied. These findings support the cortical origin of suppressive lateral interactions through short- and long-range functional connectivity. Further, synaptic inhibition likely causes a breakdown of synchronisation in the network response, consistent with the proposition that a function of surround suppression is to remove the statistical redundancies by increasing the sparseness or selectivity of sensory responses.
Meeting abstract presented at VSS 2015
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