Predictive coding in the visual cortex: a functional interpretation of some extra-classical receptive-field effects

We describe a model of visual processing in which feedback connections from a higher- to a lower-order visual cortical area carry predictions of lower -level neural activities, whereas the feedforward connections carry the res idual errors between the predictions and the actual lower-level activities. When exposed to natural images, a hierarchical network of model neurons im plementing such a model developed simple-cell-like receptive fields. A subs et of neurons responsible for carrying the residual errors showed endstoppi ng and other extra-classical receptive-field effects. These results suggest that rather than being exclusively feedforward phenomena, nonclassical sur round effects in the visual cortex may also result from cortico-cortical fe edback as a consequence of the visual system using an efficient hierarchica l strategy for encoding natural images.