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Eyal Seidemann; Decision-related activity and top-down modulations at the level of neural populations in primate V1. Journal of Vision 2014;14(15):14. doi: 10.1167/14.15.14.
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© ARVO (1962-2015); The Authors (2016-present)
What are the nature, sources and perceptual consequences of the neural variability in early sensory cortex? In this talk I will describe results from two studies that aim to begin to address these questions. In the first study, we examined co-variations between behavioral choices of monkeys performing a threshold visual detection task and neural population responses recorded simultaneously from their primary visual cortex (V1). We found that fluctuations in V1 responses to the same stimulus are highly correlated with fluctuations in perceptual decisions. By combining these results with a simple computational model we found that most choice-related variability is already present in V1. Top-down modulations from higher visual cortical areas are one potential source for the choice-related variability in V1. The goal of the second study was to characterize two possible forms of top-down effects in V1: modulations by stimulus relevance and by spatial uncertainty. We found that V1 responses are significantly modulated by stimulus relevance but not by spatial uncertainty. These relevance-based modulations are likely to contribute to gating of task-irrelevant information. However, the spatial and temporal characteristics of these top-down modulations are inconsistent with those of the choice-related variability, suggesting that choice-related variability in V1 may be dominated by bottom-up sources.
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