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Zhiyi Zhou, Melanie R. Bernard, A. B. Bonds; Synchrony modulation in cat visual cortex reflects structure from coherent motion of random dots. Journal of Vision 2006;6(6):68. doi: 10.1167/6.6.68.
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© ARVO (1962-2015); The Authors (2016-present)
Spatial features (orientation or spatial continuity) modulate synchronous activity in the visual cortex. Using moving dot patterns, we found that synchrony also detects structures generated purely by coherent motion. A 10x10 microelectrode array recorded from areas 17–18 in paralyzed and anesthetized cats and synchrony was quantified using the JPSTH (Aertsen et al. 1989). We compared responses to drifting sinusoid gratings and moving dot patterns. For dot stimuli, 10% of the background was covered by randomly distributed bright dots. In “figure” regions consisting of periodic bars, some of the dots drifted coherently, while all remaining dots both inside and outside these regions moved in random directions. The figure regions themselves moved, creating the perception of a drifting grating pattern. 203 cell pairs showed synchrony under drifting grating stimulation, and of these 63 cell pairs showed synchrony under random dot stimulation. For those pairs, a Student's t-test revealed that the synchrony amplitude for a random dot stimulus with 100% coherence is lower than that for the drifting grating stimulus (P<0.001) but higher than that for the dot stimulus with 70% coherence (P<0.001). The average firing rate for drifting gratings was twice that from random dot stimuli with 100% coherence, but the average firing rate for dot stimuli with 100% coherence did not differ significantly from those with 70% coherence (P>0.01). Synchrony detects temporally correlated structure even without clearly defined contours, but spatial integrity increases the synchrony strength. Synchrony, but not firing rate, is sensitive to the coherency level of temporally correlated structure.
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