September 27, 1999

The role of the corpus-callosum in processing information in the brain is still unclear. In order to understand what effect callosal connections have in cortical processing, this paper analyses the factors influencing the development of both intraand interhemispherical connections. Experimentally it has been observed that short-range pyramidal connections in visual cortex are largely orientation nonspecific, whilst longer range connections preferentially contact cells of the same orientation. Using a computational model of cat visual cortex it is shown that this connectivity pattern can be accounted for by assuming the probability of connection between two cells is dependent primarily on two factors receptive field overlap and orientation selectivity. The same factors can also account for many experimental observations of callosal connectivity patterns. These include the extent of the ipsilateral representation of the visual field in the ipsilateral hemisphere and the distribution of callosal cells along the V17/V18 border. The role of the corpuscallosum in the lateralization of hemispherical functions is discussed in view of these results.