Neuronal Correlates of Perceptual Salience in Spike Trains From the Primary Visual Cortex

Abstract

An extensive body of evidence indicates that visual pattern recognition is preceded by a grouping process in which images are parsed into their candidate objects, surfaces and textures. In this process, the common features of an object are thought to be rapidly associated and segregated from those belonging to other objects and the background. Further evidence indicates that much of this perceptual grouping process takes place in early cortical areas, such as striate cortex, where horizontal interactions and recurrent connections modify neuronal activity to signal relationships among image features. The nature of this modification, and the resulting representation, is not fully understood.

Thus, in this study, we investigated this representation by recording from individual neurons in the primary visual cortex of macaque monkeys while they performed a contour detection task. The visual stimuli consisted of an array of randomly drifting Gabor patches, with a subset aligned to form a coherently drifting closed contour. The orientations of the Gabor patches on the contour were jittered to create contours with high, intermediate, and low saliency. The neurons under study were either part of the contour, or were part of the background.

The goal of the proposed research is to use methods from signal detection theory to test three specific hypotheses regarding the neuronal correlates of perceptual salience: firing rate, temporal correlation, and response latency.