Detection of moving targets in the visual pathways of turtles using computational models

Microcircuits in the visual cortex of freshwater turtles have been revisited. These consist of a model of the retina, the lateral geniculate nucleus (LGN) and the visual cortex. In this paper, we present, via simulation how visual input on the retina is subsequently processed by the LGN leading up to an input to the cortex that generates a wave of activity. To gain access to the information content of the cortical wave, we analyze the extent to which these waves are able to discriminate the motion direction of the targets. The results are displayed in terms of root mean square error. We also show, via simulation, the role of the geniculate nucleus in terms of noise suppression. In particular, we show that, without the geniculate complex, retinal noise is strong enough to produce cortical activities without any form of target inputs. For realistic motion discrimination, it is imperative that noise in the geniculate is suppressed.