A Model of Contextual Interactions in Primary Visual Cortex: Examining the Influence of Corticogeniculate Feedback

Abstract

The current view of visual processing in the mammalian brain is based on the general idea that the information is transmitted from retina to neocortex via a feedforward sequence of hierarchical levels that create a detailed topographic map of the visual world. However, in reality, anatomical data show that the feedforward visual pathways are far outnumbered by corticofugal projections [1] which terminate in the LGN of the thalamus. Furthermore, electrophysiological data [2] show that the massive cortical feedback is able to modulate the processing of sensory information by determining the sensitivity of LGN neurons to visual stimuli. Despite this overwhelming neuroanatomical and neurophysiological evidence, the role of cortical feedback has not been addressed yet in relation to mechanisms of orientation selectivity and context effects. The current views completely neglect the role of recurrent feedback in favor of feedforward and horizontal connections [3, 4]. The aim of this study, therefore, is to investigate whether models that incorporate the effect of cortical feedback, in addition to feedforward and horizontal connections, can explain neurophysiological data reporting context-dependent distortions in the orientation tuning and firing pattern of cells in primary visual cortex (V1).