Geometrical relationships among multiple cortical maps, such as those between ocular dominance and orientation maps, are a prominent feature of the brain's functional architecture. It is also well known that there is a strong bias of cortical responses toward the contralateral eye during early postnatal development. We wondered therefore whether and how such an imbalance of cortical responsiveness in a developing animal might influence the mutual geometrical relationships between orientation and ocular dominance maps in adult animals. The results of our study indicate the existence of a strong tendency for the peaks of the ipsilateral eye domains to coincide with the location of point singularities (pinwheel centers) in orientation maps. No such relationship was found for the peaks of contralateral eye domains. Computational studies reproduced similar asymmetry in the coincidence under the contralateral eye bias of inputs. Our study raised the idea that the pinwheel centers play an important role for retaining the weaker ipsilateral eye inputs during normal development.
1Laboratory for Visual Neurocomputing, RIKEN BSI, Hirosawa, Wako, Saitama 351-0198
2Department of Physics, Waseda University, Japan
3Department of Physiology, University of Tokyo School of Medicine, Japan
4NEC Informatec Systems, Ltd., Japan
5Center for Magnetic Resonance Research, University of Minnesota Medical School, Minneapolis, MN, USA
6Corresponding Author: Yoshitaka Matsuda and Address: Laboratory for Visual Neurocomputing, RIKEN BSI, Hirosawa, Wako, Saitama 351-0198
Acknowledgements: We thank Dr Shigeru Tanaka for his helpful discussions and continuing support. Y.M. thanks Professor Yoshi-Hiko Ohtsuki of the Department of Physics in Waseda University for his continuous encouragement. We also thank T. Mogami, H. Nakagama, N. Iannella and M. Fukuda for useful comments on this manuscript. Computing was done on the S.A. server B of RIKEN Center System.
Received 27 June 2000; accepted 8 August 2000