The anterior ectosylvian visual area of the ferret: a homologue for an enigmatic visual cortical area of the cat?

The present paper describes the results of electrophysiological mapping experiments focused on the anterior limb of the ectosylvian gyrus of the ferret (Mustela putorius). The aim was to determine if the ferret possessed a homologous cortical area to the anterior ectosylvian visual area (AEV) of the domestic cat, but not clearly delineated in any other mammal studied to date. We were able to gather data on the visuotopic organization of a region that we consider to be a homologue of cat AEV. The visual map in this area showed a distinct visuotopic organization and covered a large extent of the visual field. Within the ferret AEV there were clusters of bimodal recording sites (somato-visual and audio-visual) that were located adjacent to surrounding unimodal cortical areas (such as the second somatosensory area and primary and secondary auditory areas). The ferret AEV, like that of the cat, was topographically isolated from other visual cortical areas by intervening auditory and somatosensory areas. Taken together these features suggest that the region described here as AEV in the ferret is indeed a direct homologue of the previously described cat AEV.