PT - JOURNAL ARTICLE AU - Roberto Caminiti AU - Gabriel Girard AU - Alexandra Battaglia-Mayer AU - Elena Borra AU - Andrea Schito AU - Giorgio M. Innocenti AU - Giuseppe Luppino TI - The Complex Hodological Architecture of the Macaque Dorsal Intraparietal Areas as Emerging from Neural Tracers and DW-MRI Tractography AID - 10.1523/ENEURO.0102-21.2021 DP - 2021 May 25 TA - eneuro PG - ENEURO.0102-21.2021 4099 - http://www.eneuro.org/content/early/2021/05/21/ENEURO.0102-21.2021.short 4100 - http://www.eneuro.org/content/early/2021/05/21/ENEURO.0102-21.2021.full 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.