The role of ipsilateral motor network in upper limb movement

Hao Ding; Nelly Seusing; Bahman Nasseroleslami; Abdul Rauf Anwar; Sebastian Strauss; Martin Lotze; Matthias Grothe; Sergiu Groppa; Muthuraman Muthuraman

doi:10.3389/fphys.2023.1199338

The role of ipsilateral motor network in upper limb movement

Front Physiol. 2023 Jul 3:14:1199338. doi: 10.3389/fphys.2023.1199338. eCollection 2023.

Authors

Hao Ding^{1

2}, Nelly Seusing³, Bahman Nasseroleslami², Abdul Rauf Anwar⁴, Sebastian Strauss³, Martin Lotze⁵, Matthias Grothe³, Sergiu Groppa⁶, Muthuraman Muthuraman¹

Affiliations

¹ Department of Neurology, University Hospital Würzburg, Würzburg, Germany.
² Academic Unit of Neurology, Trinity College Dublin, The University of Dublin, Dublin, Ireland.
³ Department of Neurology, University Medicine of Greifswald, Greifswald, Germany.
⁴ Paris Brain Institute, Paris, France.
⁵ Functional Imaging Unit, Center for Diagnostic Radiology, University Medicine Greifswald, Greifswald, Germany.
⁶ Department of Neurology, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany.

Abstract

The execution of voluntary movements is primarily governed by the cerebral hemisphere contralateral to the moving limb. Previous research indicates that the ipsilateral motor network, comprising the primary motor cortex (M1), supplementary motor area (SMA), and premotor cortex (PM), plays a crucial role in the planning and execution of limb movements. However, the precise functions of this network and its interplay in different task contexts have yet to be fully understood. Twenty healthy right-handed participants (10 females, mean age 26.1 ± 4.6 years) underwent functional MRI scans while performing biceps brachii representations such as bilateral, unilateral flexion, and bilateral flexion-extension. Ipsilateral motor evoked potentials (iMEPs) were obtained from the identical set of participants in a prior study using transcranial magnetic stimulation (TMS) targeting M1 while employing the same motor tasks. The voxel time series was extracted based on the region of interest (M1, SMA, ventral PM and dorsal PM). Directed functinal connectivity was derived from the extracted time series using time-resolved partial directed coherence. We found increased connectivity from left-PMv to both sides M1, as well as right-PMv to both sides SMA, in unilateral flexion compared to bilateral flexion. Connectivity from left M1 to left-PMv, and left-SMA to right-PMd, also increased in both unilateral flexion and bilateral flexion-extension compared to bilateral flexion. However, connectivity between PMv and right-M1 to left-PMd decreased during bilateral flexion-extension compared to unilateral flexion. Additionally, during bilateral flexion-extension, the connectivity from right-M1 to right-SMA had a negative relationship with the area ratio of iMEP in the dominant side. Our results provide corroborating evidence for prior research suggesting that the ipsilateral motor network is implicated in the voluntary movements and underscores its involvement in cognitive processes such as movement planning and coordination. Moreover, ipsilateral connectivity from M1 to SMA on the dominant side can modulate the degree of ipsilateral M1 activation during bilateral antagonistic contraction.

Keywords: bilateral motor network; ipsilateral motor evoked potential; ipsilateral motor network; upper limb; voluntary movement.

Grants and funding

The article contribution received funding support from multiple sources. It was supported by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Project-ID 424778381-TRR 295, and MU 4354/1-1 by MM. In addition, the Fondazione Grigioni per il Morbo di Parkinson to MM, also provided financial support for this research.