Visual Attention in The Fovea and The Periphery during Visual Search

Visual search depends on both the foveal and peripheral visual system, yet the foveal attention mechanisms is still lack of insights. We simultaneously recorded the foveal and peripheral activities in V4, IT and LPFC, while monkeys performed a category-based visual search task. Feature attention enhanced responses of Face-selective, House-selective, and Non-selective foveal cells in visual cortex. While foveal attention effects appeared no matter the peripheral attention effects, paying attention to the foveal stimulus dissipated the peripheral feature attentional effects, and delayed the peripheral spatial attentional effects. When target features appeared both in the foveal and the peripheral, feature attention effects seemed to occur predominately in the foveal, which might not distribute across the visual field according to common view of distributed feature attention effects. As a result, the parallel attentive process seemed to occur during distractor fixations, while the serial process predominated during target fixations in visual search.

Value signals guide abstraction during learning

The human brain excels at constructing and using abstractions, such as rules, or concepts. Here, in two fMRI experiments, we demonstrate a mechanism of abstraction built upon the valuation of sensory features. Human volunteers learned novel association rules based on simple visual features. Reinforcement-learning algorithms revealed that, with learning, high-value abstract representations increasingly guided participant behaviour, resulting in better choices and higher subjective confidence. We also found that the brain area computing value signals - the ventromedial prefrontal cortex - prioritized and selected latent task elements during abstraction, both locally and through its connection to the visual cortex. Such a coding scheme predicts a causal role for valuation. Hence, in a second experiment, we used multivoxel neural reinforcement to test for the causality of feature valuation in the sensory cortex, as a mechanism of abstraction. Tagging the neural representation of a task feature with rewards evoked abstraction-based decisions. Together, these findings provide a novel interpretation of value as a goal-dependent, key factor in forging abstract representations.