CORTICOCORTICAL CONNECTIONS BETWEEN AREA 21A AND PRIMARY VISUAL-CORTEX IN THE CAT

WE investigated the corticocortical connections between area 21a and i psilateral areas 17 and 18 in the cat. The anterograde/retrograde fluo rescent tracer tetramethylrhodamine conjugated to dextran (Fluoro-Ruby ) was injected into area 21a of the anaesthetized cat. Cell bodies lab elled retrogradely from area 21a were consistently observed in both ar eas 17 and 18, primarily located in the supragranular layers of cortex where they formed discrete patches of cells. Similar numbers of cell bodies were labelled retrogradely in areas 17 and 18 of each animal. O ur data are also consistent with previous reports of a reciprocal proj ection from area 21a back to areas 17 and 18 terminating principally i n infragranular cortical layers.