| Summary: | 博士 === 國立陽明大學 === 神經科學研究所 === 102 === Neuronal synchrony (coincident spiking, fast spike time correlation) is thought to be an essential part of cortical dynamics underlying perception, cognition, and action. However, its relationship with the functional and geometric properties of cortical circuits remains poorly understood. To relate coincident spiking to tuning and other factors, we measured synchrony based on spontaneous activity because it is the common ‘baseline’ across studies that test different stimuli, and because variations in synchrony strength are much larger across cell pairs than across stimuli suggesting that the spontaneous circuit might actually dominate the visual processing. Is the probability of coincident spiking between two neurons a graded function of lateral cortical separation, independent of functional tuning (e.g. orientation preferences)? Although previous studies reported that coincident spiking declines with lateral cortical distance, we hypothesized that, at short distances, this may be better explained by receptive field similarity. Here we measured V1 tuning via parametric stimuli and spike-triggered analysis, and we developed a generalized linear model (GLM) to quantify their relative contributions to coincident spiking, as measured during spontaneous activity. We report that coincident spiking is predicted by a combination of factors including color, spatiotemporal receptive field (STRF), and related collinear factors spatial frequency, phase and orientation, but not ocular dominance. Accounting for these factors in the model mostly eliminated the contribution of cortical distance to coincident spiking (up to our recording limit of 1.4 mm), in terms of both ‘correlation probability’ (the incidence of pairs that have significant coincident spiking) and ‘correlation strength’ (the proportion of a pair’s spikes that are coincident). We suggest that local V1 coincident spiking is determined more by tuning similarity than by cortical distance or ocular dominance.
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