Investigating the heterogeneity within the somatosensory-motor network and its relationship with the attention and default systems

Ziteng Han; Tiantian Liu; Zhongyan Shi; Jian Zhang; Dingjie Suo; Li Wang; Duanduan Chen; Jinglong Wu; Tianyi Yan

doi:10.1093/pnasnexus/pgad276

Investigating the heterogeneity within the somatosensory-motor network and its relationship with the attention and default systems

PNAS Nexus. 2023 Aug 23;2(9):pgad276. doi: 10.1093/pnasnexus/pgad276. eCollection 2023 Sep.

Authors

Ziteng Han¹, Tiantian Liu¹, Zhongyan Shi¹, Jian Zhang², Dingjie Suo¹, Li Wang¹, Duanduan Chen¹, Jinglong Wu¹, Tianyi Yan¹

Affiliations

¹ School of Medical Technology, Beijing Institute of Technology, No. 5 South Zhongguancun Street, Haidian District, Beijing 100081, China.
² School of Mechatronical Engineering, Beijing Institute of Technology, No. 5 South Zhongguancun Street, Haidian District, Beijing 100081, China.

Abstract

The somatosensory-motor network (SMN) not only plays an important role in primary somatosensory and motor processing but is also central to many disorders. However, the SMN heterogeneity related to higher-order systems still remains unclear. Here, we investigated SMN heterogeneity from multiple perspectives. To characterize the SMN substructures in more detail, we used ultra-high-field functional MRI to delineate a finer-grained cortical parcellation containing 430 parcels that is more homogenous than the state-of-the-art parcellation. We personalized the new parcellation to account for individual differences and identified multiscale individual-specific brain structures. We found that the SMN subnetworks showed distinct resting-state functional connectivity (RSFC) patterns. The Hand subnetwork was central within the SMN and exhibited stronger RSFC with the attention systems than the other subnetworks, whereas the Tongue subnetwork exhibited stronger RSFC with the default systems. This two-fold differentiation was observed in the temporal ordering patterns within the SMN. Furthermore, we characterized how the distinct attention and default streams were carried forward into the functions of the SMN using dynamic causal modeling and identified two behavioral domains associated with this SMN fractionation using meta-analytic tools. Overall, our findings provided important insights into the heterogeneous SMN organization at the system level and suggested that the Hand subnetwork may be preferentially involved in exogenous processes, whereas the Tongue subnetwork may be more important in endogenous processes.

Keywords: brain networks; fMRI; functional connectivity; somatosensory-motor network.