Topographic and somatotopic organization of functional connectivity between the intraparietal sulcus and primary somatosensory cortex in macaque monkeys
- 1Institut des Sciences Cognitives Marc Jeannerod, UMR5229, CNRS-University of Lyon 1, Lyon, France
Abstract
The posterior parietal cortex integrates somatosensory information with signals supporting action, spatial cognition, and multisensory processing, yet the fine-scale topographic relationship between the intraparietal sulcus (IPS) and primary somatosensory cortex (S1) remains poorly understood. Here, we used resting-state fMRI in 10 awake rhesus macaques to characterize functional connectivity between four S1 subregions (areas 3a, 3b, 1, and 2) and 223 single-voxel seeds densely sampling an IPS-centered parietal territory. Across S1 subregions and hemispheres, IPS-S1 connectivity exhibited a highly structured spatial organization characterized by systematic anteroposterior and mediolateral gradients and a prominent semi-oval topology following the geometry of the intraparietal sulcus. Connectivity was generally stronger toward the cortical banks and convexities and weaker near the sulcal fundus, a pattern that could not be explained by reduced local temporal signal-to-noise ratio. Unsupervised hierarchical clustering independently recovered this spatial organization and identified connectivity-defined subdivisions that only partially corresponded to classical cytoarchitectonic boundaries. Along the S1 mediolateral axis, prominent troughs in cluster-averaged connectivity profiles corresponded to several previously described somatotopic transitions, allowing to consistently map putative boundaries between tongue and face representations and between hand and trunk-leg representations. Based on these boundaries, individual IPS clusters exhibited connectivity with multiple S1 body-part sectors, with the pattern of connectivity across these sectors varying across IPS clusters and S1 subregions. Together, our findings reveal that IPS-S1 functional connectivity is organized by a large-scale sulcal topology while preserving fine-grained features of S1 somatotopic organization. These findings suggest that the functional organization of the IPS is shaped by multiple spatial dimensions, including large-scale sulcal topology and the organization of S1 subregions and body-part representations, which may together contribute to the functional specialization of individual IPS regions.
Related
- Somatotopic Organization of Sensory Inputs From Taste Appendages in the Subesophageal Zone and Brain of the Honey Bee Apis mellifera
- Somatotopic functional connectivity gradients in the monkey and human striatum.
- Somatotopic Organization of the Ventroposterior Nucleus of the Thalamus in Macaque Monkeys with Dorsal Spinal Cord Injuries Sustained During Early Postnatal Development
- Postnatal maturation of putamen microstructure accompanies topographic white matter connectivity and altered circuits in autism
- Three dimensional reconstruction of the human nucleus accumbens reveals topographic organization and molecular heterogeneity of D1-islands across the anterior posterior axis
BibTeX
@misc{sheng2026topographic,
title = {{Topographic and somatotopic organization of functional connectivity between the intraparietal sulcus and primary somatosensory cortex in macaque monkeys}},
author = {W.-A. Sheng and S. Clavagnier and M. Froesel and T. Heed and W. Vanduffel and S. Ben Hamed},
howpublished = {bioRxiv},
year = {2026},
month = sep,
doi = {10.64898/2026.09.19.752858},
url = {https://www.biorxiv.org/content/10.64898/2026.09.19.752858v1},
note = {CC BY-NC},
}
RIS
TY - UNPB
TI - Topographic and somatotopic organization of functional connectivity between the intraparietal sulcus and primary somatosensory cortex in macaque monkeys
AU - W.-A. Sheng
AU - S. Clavagnier
AU - M. Froesel
AU - T. Heed
AU - W. Vanduffel
AU - S. Ben Hamed
PY - 2026
DA - 2026/09/19
PB - bioRxiv
DO - 10.64898/2026.09.19.752858
UR - https://www.biorxiv.org/content/10.64898/2026.09.19.752858v1
AB - The posterior parietal cortex integrates somatosensory information with signals supporting action, spatial cognition, and multisensory processing, yet the fine-scale topographic relationship between the intraparietal sulcus (IPS) and primary somatosensory cortex (S1) remains poorly understood. Here, we used resting-state fMRI in 10 awake rhesus macaques to characterize functional connectivity between four S1 subregions (areas 3a, 3b, 1, and 2) and 223 single-voxel seeds densely sampling an IPS-centered parietal territory. Across S1 subregions and hemispheres, IPS-S1 connectivity exhibited a highly structured spatial organization characterized by systematic anteroposterior and mediolateral gradients and a prominent semi-oval topology following the geometry of the intraparietal sulcus. Connectivity was generally stronger toward the cortical banks and convexities and weaker near the sulcal fundus, a pattern that could not be explained by reduced local temporal signal-to-noise ratio. Unsupervised hierarchical clustering independently recovered this spatial organization and identified connectivity-defined subdivisions that only partially corresponded to classical cytoarchitectonic boundaries. Along the S1 mediolateral axis, prominent troughs in cluster-averaged connectivity profiles corresponded to several previously described somatotopic transitions, allowing to consistently map putative boundaries between tongue and face representations and between hand and trunk-leg representations. Based on these boundaries, individual IPS clusters exhibited connectivity with multiple S1 body-part sectors, with the pattern of connectivity across these sectors varying across IPS clusters and S1 subregions. Together, our findings reveal that IPS-S1 functional connectivity is organized by a large-scale sulcal topology while preserving fine-grained features of S1 somatotopic organization. These findings suggest that the functional organization of the IPS is shaped by multiple spatial dimensions, including large-scale sulcal topology and the organization of S1 subregions and body-part representations, which may together contribute to the functional specialization of individual IPS regions.
ER -