RT Journal Article SR Electronic T1 The Complex Hodological Architecture of the Macaque Dorsal Intraparietal Areas as Emerging from Neural Tracers and DW-MRI Tractography JF eneuro JO eNeuro FD Society for Neuroscience SP ENEURO.0102-21.2021 DO 10.1523/ENEURO.0102-21.2021 A1 Roberto Caminiti A1 Gabriel Girard A1 Alexandra Battaglia-Mayer A1 Elena Borra A1 Andrea Schito A1 Giorgio M. Innocenti A1 Giuseppe Luppino YR 2021 UL http://www.eneuro.org/content/early/2021/05/21/ENEURO.0102-21.2021.abstract AB 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. Combining retrograde histological tracing and MRI diffusion-based tractography we found a complex hodology 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 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 neural tracers. For most connections, we found a significant correlation 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. The latter also revealed “false positive” but plausible streamlines awaiting histological validation.Significance StatementCombined histological and DW-MRI tractography revealed that intraparietal areas PEip and MIP share common inputs from other parietal, frontal and, to a lesser extent, cingulate areas, although with different gradient-like connectivity profiles. Both tractography and histology revealed a high number of common paths, although tractography showed false positive connections awaiting histological validation. A correlation was performed between the proportion of labelled cells projecting to PEip and MIP and the diffusion-based connectivity estimation of the regions of interest corresponding to the injection sites of retrograde tracers. The results showed a significant correlation from most connections studied, opening a window for future studies contrasting proportions of cells giving rise to the fiber bundles connecting cortical areas with measures of diffusion tractography connectivity.