The cortico-cortical connections within the parieto-temporal lobe of area PG,7a, in the monkey.

After injections of HRP into area PG(7a) labelled cells have been found in architectonic areas OA, PE, the cingulate and retrosplenial areas medial to area PG; posteriorly areas MST, OA (V4), V2, V3 and the cortex in the walls and floor of the superior temporal sulcus have also been labelled. Small injections placed in PG have resulted in different parts of these areas being labelled, suggesting that these cortico-cortical connections are well organized and raising the possibility of an ordered representation of the visual field in PG. It is suggested that the vertical meridian is around the boundary and the horizontal meridian passes antero-posteriorly across about the middle of its medio-lateral extent; the central part of the visual field is in the depths of the intraparietal sulcus, and the periphery is on the surface of the inferior parietal lobule and in the anterior wall of the upper part of the superior temporal sulcus. The lower visual field is medial and the upper field is lateral.