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 residual errors between the predictions and the actual lower-level activities. When exposed to natural images, a hierarchical network of model neurons implementing such a model developed simple-cell-like receptive fields. A subset of neurons responsible for carrying the residual errors showed endstopping and other extra-classical receptive-field effects. These results suggest that rather than being exclusively feedforward phenomena, nonclassical surround effects in the visual cortex may also result from cortico-cortical feedback as a consequence of the visual system using an efficient hierarchical strategy for encoding natural images.
Rao
R P
RP
Salk Institute, Sloan Center for Theoretical Neurobiology, La Jolla, California, USA. rao@salk.edu
Ballard
D H
DH
D005246:Feedback; D005544:Forecasting; D008959:Models, Neurological; D016571:Neural Networks, Computer; D014793:Visual Cortex / Q000502:physiology*; D014795:Visual Pathways / Q000502:physiology