EN
To determine surface-view connectivity patterns of area 18, separate injections of up to six anatomical tracers were delivered to various rostrocaudal locations of area 18 in six normal cats.Subsequently, cortex was separated from subcortical structures, mannually flattened, and cut parallel to the surface.Result reveal that ipsilateral cortical connections of area 18 with three region of cortex are topological. In areas 17 and 19, separate patches of cells labeled with different tracers progressed in a rostrocaudal sequence corresponding to the order of the injections.A similar but less precise pattern of rostrocaudal labelling occured in more lateral visual cortex, even though several presumptive visual areas were involved.Thus anteromedial suprasylvian cortex projected to anterior area 18 while more posterolateral suprasylvian cortex projected to postrior area 18.There was no evidence of double-labelled cells projecting to separate regions in area 18.These results are more consistent with the concept of a single suprasylvian area projecting to area 18 cortex than several.