Cortical connections of the dorsomedial visual area in Old World macaque monkeys

The connections of a wedge of densely myelinated cortex along the dorsomedial border of V2 were determined by injecting tracers into this region in macaque monkeys. According to previous descriptions, this cortex would constitute parts of dorsal V3 and V3A, or a dorsomedial visual area, DM, homologous to the DM described in prosimians and New World monkeys. Injections of wheat germ agglutinin conjugated to horseradish peroxidase or various fluorescent tracers demonstrated connections with architectonically defined V1, V2, and the middle temporal area, as well as regions of visual areas known as the ventral posterior parietal area, the rostral dorsolateral area or rostral V4, ventral posterior cortex and more rostral cortex in the ventral temporal lobe, and medial and dorsointermediate areas. Other sparser and less consistently revealed connections were with the medial superior temporal area, the area of the fundus of the superior temporal sulcus, and the caudal dorsolateral area. Distributions of labeled cells in V1 varied in relationship to the pattern of cytochrome oxidase blobs and interblobs in a manner suggesting a heterogeneous pattern of terminations from blob and interblob regions within DM. Major similarities in overall connections of the DM region in macaques with DM connections described in New World monkeys and prosimian galagos support the conclusion that the same visual area, DM, has been identified in all these primates.