ABSTRACT In macaque monkeys, dorsal intraparietal areas are involved in several daily visuo-motor actions. However, their border and sources of cortical afferents remain loosely defined. Through a retrograde tracer and MRI diffusion-based tractography study here we show a complex organization of the dorsal bank of the IPS, which can be subdivided into a rostral area PEip, projecting to the spinal cord, and a caudal area MIP lacking such projections. Both areas include a rostral and a caudal sector, emerging from their ipsilateral, gradient-like connectivity profiles. As tractography estimations, we used the cross-sectional volume of the white matter bundles connecting each area with other parietal and frontal regions, after selecting ROIs corresponding to the injection sites of retrograde tracers. A quantitative analysis between the proportions of cells projecting to all sectors of PEip and MIP along the continuum of the dorsal bank of the IPS and tractography revealed a significant correlation between the two data sets for most connections. Moreover, tractography revealed “false positive” but plausible streamlines awaiting histological validation.

THE COMPLEX HODOLOGICAL ARCHITECTURE OF THE MACAQUE DORSAL INTRAPARIETAL AREAS AS EMERGING FROM NEURAL TRACERS AND DW-MRI TRACTOGRAPHY