RELATIONSHIP BETWEEN MULTIPLE STIMULUS FEATURE MAPS IN FERRET VISUAL CORTEX. H. Yu; B.J. Farley; J. Sharma; M. Sur* Brain and Cognitive Sciences, M.I.T., Cambridge, MA, USA We used optical imaging of intrinsic signals in ferret visual cortex to simultaneously examine stimulus feature maps of ocular dominance, orientation, spatial frequency and direction. Visual cortex was segregated into unusually broad ocular dominance bands that tended to be elongated mediolaterally. The particular shape and extent of these bands varied appreciably between animals (cf White et al., J. Neurosci. 19:7089, 1999). Within each eye's ocular dominance band, multiple orientation pinwheel centers were represented. Iso-orientation lines tended to cross the borders of ocular dominance domains at right angles, and orientation vector magnitude fracture lines did not run along ocular dominance borders. This suggests that the pattern of ocular dominace bands does not disrupt the continuity of orientation representation. Cortex activated by high spatial frequency appeared restricted to near the occipital pole, whereas lower spatial frequencies caused activation to spread rostrally. Within iso-orientation domains, activation regions elicited by opposite directions tended to be displaced, and regions representing different spatial frequencies appeared shifted. Our results indicate both local and large-scale regulation of feature maps in ferret visual cortex. Orientation, direction and spatial frequency appear to be continuously mapped over local cortical regions. The segregation of cortex into broad ocular dominance bands requires that coverage of visual space by the two eyes include large regions of cortex. Yet, the regular relationship between ocular dominance borders and orientation columns suggests a uniform mapping rule linking the two and possibly other columnar systems. Supported by: NIH grant 000011284