Cortical parallel processing streams segregate many diverse features of a sensory scene. However, some features are distributed across streams, begging the question of whether and how such distributed representations contribute to perception. We determined the necessity of the primary visual cortex (V1) and three key higher visual areas (lateromedial [LM], anterolateral [AL], and posteromedial [PM]) for perception of orientation and contrast, two features that are robustly encoded across all four areas. Suppressing V1, LM, or AL decreased sensitivity for both orientation discrimination and contrast detection, consistent with a role for these areas in sensory perception. In comparison, suppressing PM selectively increased false alarm (FA) rates during contrast detection, without any effect on orientation discrimination. This effect was not retinotopically specific, suggesting that suppression of PM altered sensory integration or the decision-making process rather than processing of local visual features. Thus, we find that distributed representations in the visual system can nonetheless support specialized perceptual roles for higher visual cortical areas.
Keywords: contrast; d-prime; decision-making; false alarm; mouse visual cortex; optogenetics; orientation; psychophysics; sensory processing; speed.
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