Consistent mapping of orientation preference across irregular functional domains in ferret visual cortex

The mammalian visual cortex harbors a number of functional maps that repres ent distinct attributes of stimuli in the visual environment. Wow different functional maps are accommodated within the same cortical space, especiall y in species that show marked irregularities in one or more functional maps , remains poorly understood. We used optical imaging of intrinsic signals a nd electrophysiological techniques to investigate the organization of the m aps of orientation preference, ocular dominance, and visual space in ferret . This species shows striking nonuniformity in the arrangement of ocular do minance domains and disruption of the mapping of visual space along the V1/ V2 border. We asked whether these irregularities would be reflected in the organization of the map of orientation preference. The results show that or ientation preference is mapped consistently within both V1 and V2, and acro ss the interareal boundary, with no reflection of the irregularities in the other maps. These observations demonstrate the accommodation of multiple f unctional maps within the same cortical space without systematic geometrica l relationships that necessarily constrain the organization of each represe ntation. Furthermore, they imply that the structure of the map of orientati on preference reflects the architecture and activity patterns of cortical c ircuits that are independent of other columnar systems established in layer 4.