Ipsilateral visual field represented in the cat's visual cortex

Responses to visual stimulation were recorded in cells from the border region between cortical areas 17 and 18 in anaesthetized cats. There was found to be a band of ipsilateral representation, the cells of which had rather large receptive fields centered up to 8-12 degrees into the ipsilateral hemifield. The edges of the receptive fields extended 2-3 degrees still further ipsilaterally. The cortical region involved is very small, however, stretching 0.2-1.0 mm mediolaterally, and possibly restricted largely to layers II and III. Hence, in cats, as in sheep and hamsters, there is a band about 20 degrees wide of visual field along the naso-temporal division that is represented in the visual cortices of both hemispheres.