Color Columns in Visual Area V4

Abstract

SummaryModels of the cerebral cortex propose a canonical columnar architecture preserved across the brain. Evidence for this model primarily stems from observations in primary sensory areas, such as the visual cortex, where neurons in an anatomical column respond preferentially to the same stimulus features. Similar columnar feature selectivity has been described for visual area V2, visual area V3 [9, 10], the middle temporal visual area (area V5), and inferotemporal cortex. The fourth visual area (V4) features color selective neurons, organized in clusters across its surface. However, whether these color-sensitive neurons are organized in a columnar fashion is debated and uncertain due to technical limitations. Here, we utilize laminar multielectrode recordings along V4 columns to resolve rival hypotheses. Linear electrode arrays were introduced orthogonally into area V4, spanning all cortical layers. Monkeys viewed color stimuli presented to the visual receptive field of the column of neurons. We found that preference for a specific color was conserved along depth but varied across columns. Interestingly, while color preference (e.g. red or green) was consistent along depth, color selectivity was significantly greater in upper layers relative to the input layer and was weakest in the lower layers. These findings demonstrate that area V4 is organized in functional columns like other visual areas.

Keywords: Cortical Layers, Feature-selectivity, Macaque, Microcircuitry, Visual Cortex