14C-deoxyglucose mapping of orientation subunits in the cats visual cortical areas

The orientation domain in the cortical visual areas of anesthetized cats has been investigated by employing the 14C-deoxyglucose technique (Sokoloff et al., 1977). Orientation subunits (OS) are seen in the first (V1), the second (V2) and the third visual area (V3) as well as in the visual areas of the suprasylvian sulcus. In the latter regions OS are less elaborated than in V1, V2, and V3. The OS are continuous through all cortical layers; in V1 however, only weak label is detected in layer 4C. In V1, V2, and V3 the width of the OS is about 0.4 mm and the average distance between two OS centers is 0.9 mm. The spatial pattern of the OS seems to be more regular in the visual field periphery than in regions representing the vertical meridian.