A computational model of perceptual fill-in following retinal degeneration.
The ablation of afferent input results in the reorganization of sensory and motor cortices. In the primary visual cortex (V1), binocular retinal lesions deprive a corresponding cortical region [lesion projection zone (LPZ)] of visual input. Nevertheless, neurons in the LPZ regain responsiveness by shifting their receptive fields (RFs) outside the retinal lesions; this re-emergence of neural activity is paralleled by the perceptual completion of disrupted visual input in human subjects with retinal damage. To determine whether V1 reorganization can account for perceptual fill-in, we developed a neural network model that simulates the cortical remapping in V1. The model shows that RF shifts mediated by the plexus of spatial- and orientation-dependent horizontal connections in V1 can engender filling-in that is both robust and consistent with psychophysical reports of perceptual completion. Our model suggests that V1 reorganization may underlie perceptual fill-in, and it predicts spatial relationships between the original and remapped RFs that can be tested experimentally. More generally, it provides a general explanation for adaptive functional changes following CNS lesions, based on the recruitment of existing cortical connections that are involved in normal integrative mechanisms.
McManus
Justin N J
JN
Rockefeller University, 1230 York Avenue, New York, NY 10065, USA.
Ullman
Shimon
S
Gilbert
Charles D
CD
D000465:Algorithms; D003198:Computer Simulation; D006801:Humans; D008268:Macular Degeneration / Q000503:physiopathology / Q000523:psychology; D008959:Models, Neurological; D015233:Models, Statistical; D016571:Neural Networks, Computer; D009474:Neurons / Q000502:physiology; D012162:Retinal Degeneration / Q000503:physiopathology* / Q000523:psychology; D012165:Retinal Ganglion Cells / Q000502:physiology; D014793:Visual Cortex / Q000166:cytology / Q000502:physiology; D014794:Visual Fields / Q000502:physiology; D014796:Visual Perception / Q000502:physiology*