Probing intrahemispheric interactions with a novel dual-site TMS setup

Melina Hehl; Shanti Van Malderen; Marc Geraerts; Raf L J Meesen; John C Rothwell; Stephan P Swinnen; Koen Cuypers

doi:10.1016/j.clinph.2023.12.128

Probing intrahemispheric interactions with a novel dual-site TMS setup

Clin Neurophysiol. 2024 Feb:158:180-195. doi: 10.1016/j.clinph.2023.12.128. Epub 2024 Jan 5.

Authors

Melina Hehl¹, Shanti Van Malderen¹, Marc Geraerts², Raf L J Meesen³, John C Rothwell⁴, Stephan P Swinnen⁵, Koen Cuypers⁶

Affiliations

¹ Movement Control & Neuroplasticity Research Group, Department of Movement Sciences, Group Biomedical Sciences, KU Leuven, 3001 Heverlee, Belgium; KU Leuven, Leuven Brain Institute (LBI), Leuven, Belgium; Neuroplasticity and Movement Control Research Group, Rehabilitation Research Institute (REVAL), Hasselt University, Diepenbeek, Belgium.
² Neuroplasticity and Movement Control Research Group, Rehabilitation Research Institute (REVAL), Hasselt University, Diepenbeek, Belgium.
³ Movement Control & Neuroplasticity Research Group, Department of Movement Sciences, Group Biomedical Sciences, KU Leuven, 3001 Heverlee, Belgium; Neuroplasticity and Movement Control Research Group, Rehabilitation Research Institute (REVAL), Hasselt University, Diepenbeek, Belgium.
⁴ Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, University College London, London, United Kingdom.
⁵ Movement Control & Neuroplasticity Research Group, Department of Movement Sciences, Group Biomedical Sciences, KU Leuven, 3001 Heverlee, Belgium; KU Leuven, Leuven Brain Institute (LBI), Leuven, Belgium.
⁶ Movement Control & Neuroplasticity Research Group, Department of Movement Sciences, Group Biomedical Sciences, KU Leuven, 3001 Heverlee, Belgium; KU Leuven, Leuven Brain Institute (LBI), Leuven, Belgium; Neuroplasticity and Movement Control Research Group, Rehabilitation Research Institute (REVAL), Hasselt University, Diepenbeek, Belgium. Electronic address: [email protected].

PMID: 38232610
DOI: 10.1016/j.clinph.2023.12.128

Abstract

Objective: Using dual-site transcranial magnetic stimulation (dsTMS), the effective connectivity between the primary motor cortex (M1) and adjacent brain areas such as the dorsal premotor cortex (PMd) can be investigated. However, stimulating two brain regions in close proximity (e.g., ±2.3 cm for intrahemispheric PMd-M1) is subject to considerable spatial restrictions that potentially can be overcome by combining two standard figure-of-eight coils in a novel dsTMS setup.

Methods: After a technical evaluation of its induced electric fields, the dsTMS setup was tested in vivo (n = 23) by applying a short-interval intracortical inhibition (SICI) protocol. Additionally, the intrahemispheric PMd-M1 interaction was probed. E-field modelling was performed using SimNIBS.

Results: The technical evaluation yielded no major alterations of the induced electric fields due to coil overlap. In vivo, the setup reliably elicited SICI. Investigating intrahemispheric PMd-M1 interactions was feasible (inter-stimulus interval 6 ms), resulting in modulation of M1 output.

Conclusions: The presented dsTMS setup provides a novel way to stimulate two adjacent brain regions with fewer technical and spatial limitations than previous attempts.

Significance: This dsTMS setup enables more accurate and repeatable targeting of brain regions in close proximity and can facilitate innovation in the field of effective connectivity.

Keywords: Dorsal premotor cortex (PMd); Dual-site TMS (dsTMS); Effective functional connectivity; Intrahemispheric interaction; Transcranial magnetic stimulation (TMS).

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Evoked Potentials, Motor* / physiology
Head
Humans
Motor Cortex* / physiology
Transcranial Magnetic Stimulation / methods