Simulated Optical Imaging of Orientation Preference in a Model of V1

Optical imaging studies have played an important role in mapping the orientation selectivity and ocular dominance of neurons across an extended area of primary visual cortex (V1). Such studies have produced images with a more or less smooth and regular spatial distribution of relevant neuronal response properties. This is in spite of the fact that results from electrophysiological recordings, though limited in their number and spatial distribution, show significant scatter/variability in the relevant response properties of nearby neurons. In this paper we present a simulation of the optical imaging experiments of ocular dominance and orientation selectivity using a computational model of the primary visual cortex. The simulations assume that the optical imaging signal is proportional to the averaged response of neighboring neurons. The model faithfully reproduces ocular dominance columns and orientation pinwheels in the presence of realistic scatter of single cell preferred responses. In addition,we find the simulated optical imaging of orientation pinwheels to be remarkably robust, with the pinwheel structure maintained up to an addition of degrees of random scatter in the orientation preference of single cells. Our results suggest that an optical imaging result does not necessarily, by itself, provide any obvious upperbound for the scatter of the underlying neuronal response properties on local scales. Keywords— visual cortex, orientation hypercolumn, orientation pinwheel, optical imaging, ocular dominance column