EVIDENCE FOR VISUAL CORTICAL AREA HOMOLOGS IN CAT AND MACAQUE MONKEY

The maps of visuotopically discrete visual cerebral cortical areas in the cat and the macaque monkey are compared and gaps in knowledge are identified that limit such comparisons. Cat areas 17, 18, and 19 can be equated with macaque areas V1, V2, and V3, respectively, based on criteria of relative position in the cortical mantle, internal organization of visual field representations, and trans- and subcortical connections. Using these same criteria, a visual area on the medial bank of the lateral suprasylvian sulcus (area PMLS) in the cat can be equated with macaque area V5. The equivalences are supported by data on neuronal receptive field properties and the contributions the areas make to visual behavior. Although the data are scanty for most other visual areas, there are enough data tentatively to equate collectively cat areas 20a and 20b with macaque areas TF and TH and to liken cat areas 21a and 21b with macaque area V4. What is not clear is if there is a region in cat that is equivalent to area TE in the macaque monkey. If there is, it likely lies on the banks of the posterior suprasylvian sulcus between areas 20 and 21 and the polysensory cortex of the posterior ectosylvian gyrus. Knowledge gained from prior research on macaque areas V4 and TE can be used to formulate specific additional investigations of cat area 21 and the uncharted posterior suprasylvian sulcus. In addition, prior investigations carried out on cat area 20 can be used to devise specific explorations of macaque areas TF and TH.