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RELATIONSHIPS BETWEEN ORIENTATION AND OCULAR DOMINANCE MAPS IN CAT AREA 18.

Picower Ctr. for Learning & Memory, Dept. Brain & Cognitive Sci, MIT, Cambridge, MA, USA

Multiple stimulus feature maps exist in primary visual cortex, and specific relationships between them help to achieve a more complete representation of all possible feature combinations. In cat area 17 iso-orientation and ocular dominance domains are isotropic, but in cat area 18 orientation domains are highly elongated. Using optical imaging of intrinsic signals, we determined whether there is a corresponding change in the pattern of ocular dominance in area 18, and whether spatial relationships between orientation and ocular dominance maps are conserved across areas. We found that, despite the orientation map having domains that are elongated, ocular dominance domains in cat area 18 remained isotropic. Spatial relationships between orientation and ocular dominance maps were similar in both area 17 and 18: there was a tendency for contours of the two maps to intersect at near orthogonal angles, and there was a negative correlation between the gradients of the two maps. Further investigation demonstrated that the strength of each of these spatial relationships differed in local areas of cortex: in the region with the strongest orthogonal intersection relationship, the negative correlation between orientation and ocular dominance gradients was the weakest, while the region with near parallel contours demonstrated the strongest negative correlation between gradients. The differential distribution across cortex of each relationship may reflect the need for multiple strategies to achieve uniform coverage of features whose mapping patterns can be heterogeneous. Displacing one map artificially with respect to the other led to the deterioration of these two relationships. Thus precise relationships between these maps are conserved across area 17 and 18, even though the overall structure of the orientation map differs greatly between the two areas.
Support Contributed By: NIH grant EY07023

Citation:
H. Yu, B.J. Farley, M. Sur. RELATIONSHIPS BETWEEN ORIENTATION AND OCULAR DOMINANCE MAPS IN CAT AREA 18. Program No. 818.5. 2003 Abstract Viewer/Itinerary Planner. Washington, DC: Society for Neuroscience, 2003. Online.