Connections of inferior temporal areas TEO and TE with parietal and frontal cortex in macaque monkeys

Inferior temporal cortex is perhaps the highest visual processing area and much anatomical work has focused on its connections with other visual areas in temporal and occipital cortex. Here we report connections of inferior temporal cortex with regions in the frontal and parietal lobes. Inferior temporal areas TEO and TE were injected with WGA-HRP and 3H-AA, respectively, or vice versa, in 1-week-old infant and 3-4-year-old adult monkeys (Macaca mulatta). The results indicated that whereas TEO has more extensive connections with parietal areas, TE has more extensive connections with prefrontal areas. Thus, in the intraparietal sulcus, area TEO is connected with areas LIPd, LIPv, and V3A, and with the as yet undefined region between LIPv and V3A, whereas the connections of TE are predominantly with LIPd, and to a lesser extent with LIPv. In the prefrontal cortex, area TE is connected with areas 8 and 45 in the inferior limb of the anterior bank of the arcuate sulcus, with area 12 on the inferior prefrontal convexity, and with areas 11 and 13 on the orbital surface. By contrast, the connections of area TEO are limited to areas 8, 45, and 12. Furthermore, within prefrontal cortex, the projections from areas TEO and TE terminate in different layers in areas 8 and 45, such that those from TEO terminate in all layers, whereas those from TEO terminate in layers I and V/VI only. In contrast to the connections of areas TEO and TE with various medial temporal-lobe and subcortical structures, which are immature in infant monkeys (Webster et al., 1991, 1993b), the connections with parietal and prefrontal areas appear adult-like as early as 1 week of age.