Response sub-additivity and variability quenching in visual cortex

Abstract

Sub-additivity and variability are ubiquitous response motifs in the primary visual cortex (V1). Response subadditivity provides an indication of the brain processes that enable the construction of useful interpretations of the visual environment (that is, nonlinear input transformations), while response variability provides an indication of the factors that limit the precision with which the brain can do this (that is, neural information loss). Historically, these two motifs have been studied independently of each other. However, there is increasing evidence that experimental manipulations that elicit response sub-additivity often also quench response variability. Here we provide an overview of these phenomena and suggest that response sub-additivity and variability quenching may have common origins. We discuss empirical findings as well as recent model-based insights into the functional operations, computational objectives and circuit mechanisms underlying V1 activity. Although these modeling approaches address different aspects of cortical activity, they all predict that response sub-additivity and variability quenching will often co-occur. Response sub-additivity and variability quenching are not limited to V1 but are widespread cortical phenomena. Furthermore, many of the insights obtained in V1 generalize to other cortical areas. Thus, the connection between response sub-additivity and variability quenching may be a canonical motif across the cortex.

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