THE mammalian striate cortex is organized such that the receptive field properties of neighboring neurons change gradually across the cortical surface, forming so-called cortical maps. The presence of such maps has been demonstrated in different species of mammals for several parameters characterizing the visual space: retinotopy, ocular dominance, orientation, direction of motion and spatial frequency. In this study we used the optical imaging of intrinsic signals to simultaneously record the multiple functional maps in the same animal in order to obtain a comprehensive set of rules that govern mutual dependencies among the functional maps. Our results indicate that while orientation, direction and ocular dominance are represented on the cortex in a mutually dependent manner, the representation of spatial frequency is independent of the other types of cortical representations. The presence and/or absence of mutual dependence among the multiple functional maps are suggested to provide an important clue for the understanding of the development of visual cortical information representation in neonatal animals.
1Brain Science Institute (RIKEN), Wako, Saitama 351-0198, Japan
2Center for Magnetic Resonance Research, University of Minnesota Medical School, 2021 6th Street SE, Minneapolis, MN 55455, USA
3Department of Physics, Waseda University, Japan
4Department of Physiology, University of Tokyo School of Medicine, Japan
5PRESTO, JST, Japan
6Corresponding Author and Address: Dae-Shik Kim, Center for Magnetic Resonance Research, University of Minnesota Medical School, 2021 6th Street SE, Minneapolis, MN 55455, USA
ACKNOWLEDGMENTS: The authors thank Tomoya Saito at NEC Informatec for his assistance and cooperation in computer calculations and visualization of maps used in this paper.
Received 18 May 1999; accepted 12 June 1999