The proposed project will investigate the cortical basis of image interpolation - the brain's ability to """"""""fill-in"""""""" portions of the visual scene by utilizing color, texture, and contour information form the surrounding area. The spatial extent and temporal dynamics of this process have not yet been adequately characterized. Evidence for cortical image interpolation will be evaluated by using reverse correlation methods to estimate receptive field in two conditions - a full-view condition, and a masked condition in which a portion of the stimulus falling within the cell's receptive field is occluded by a uniform grey mask thereby generating an artificial scotoma. Standard models of V1 simple cells (Gabor filters followed by a static nonlinearity) predict that in the masked condition, a """"""""hole"""""""" coincident with the location of the mask should be evident in the recovered receptive field. In contrast, pilot data indicate that some V1 neurons are able to interpolate missing information in the masked condition - their response kernels are almost identical to the full-view condition kernels. The proposed experiments will systematically investigate the degree to which masks of varying size are filled; the time required for the interpolation process; the spatial extent of the surround information used in the process; and the laminar dependence of the phenomenon. A potential application of these results would be the incorporation of image interpolation in microstimulation protocols in artificial vision systems - cortical prostheses - providing restoration of visual function for the blind using relatively sparse electrode arrays.
| Malone, Brian J; Ringach, Dario L (2008) Dynamics of tuning in the Fourier domain. J Neurophysiol 100:239-48 |
| Ringach, Dario L; Malone, Brian J (2007) The operating point of the cortex: neurons as large deviation detectors. J Neurosci 27:7673-83 |
| Malone, Brian J; Kumar, Vikas R; Ringach, Dario L (2007) Dynamics of receptive field size in primary visual cortex. J Neurophysiol 97:407-14 |
