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Does it Matter? Investigating the Association of White Matter Micro- and Macrostructure with Short-Term TMS Outcomes in the Language Network

Thoma, Sophie LU (2026) PSYP01 20261
Department of Psychology
Abstract
Transcranial magnetic stimulation (TMS) enables causal investigation of brain-behavior relationships but exhibits substantial interindividual variability. White matter pathways, which propagate stimulation-induced signals, may contribute to this variability, yet their role remains unclear. Moreover, prior work has not accounted for individual hemispheric dominance, which may further compound this variability. Here this study applied 1 Hz offline repetitive TMS over the left and right inferior frontal gyrus (IFG) and vertex in 36 participants, combined with diffusion MRI tractography and functional MRI during phonological and control tasks. Thus, this study assessed white matter microstructure (i.e. hindrance-modulated orientational... (More)
Transcranial magnetic stimulation (TMS) enables causal investigation of brain-behavior relationships but exhibits substantial interindividual variability. White matter pathways, which propagate stimulation-induced signals, may contribute to this variability, yet their role remains unclear. Moreover, prior work has not accounted for individual hemispheric dominance, which may further compound this variability. Here this study applied 1 Hz offline repetitive TMS over the left and right inferior frontal gyrus (IFG) and vertex in 36 participants, combined with diffusion MRI tractography and functional MRI during phonological and control tasks. Thus, this study assessed white matter microstructure (i.e. hindrance-modulated orientational anisotropy) and macrostructure (i.e. tract volume) of language-related tracts and modeled induced electric field strength. While TMS did not produce group-level behavioral changes, stronger electric fields in the dominant hemisphere correlated with post-stimulation slowing. Only microstructure of the posterior arcuate fasciculus predicted improved control task efficiency after dominant-hemisphere stimulation. No white matter metrics predicted neural activation changes. These findings suggest that white matter properties weakly influence short-term behavioral and neural responses to IFG stimulation, possibly due to compensatory network mechanisms during distributed task engagement. (Less)
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author
Thoma, Sophie LU
supervisor
organization
course
PSYP01 20261
year
type
H2 - Master's Degree (Two Years)
subject
keywords
transcranial magnetic stimulation, white matter structure, diffusion MRI, hemispheric dominance, language network
language
English
id
9251041
date added to LUP
2026-09-15 10:58:34
date last changed
2026-09-15 10:58:34
@misc{9251041,
  abstract     = {{Transcranial magnetic stimulation (TMS) enables causal investigation of brain-behavior relationships but exhibits substantial interindividual variability. White matter pathways, which propagate stimulation-induced signals, may contribute to this variability, yet their role remains unclear. Moreover, prior work has not accounted for individual hemispheric dominance, which may further compound this variability. Here this study applied 1 Hz offline repetitive TMS over the left and right inferior frontal gyrus (IFG) and vertex in 36 participants, combined with diffusion MRI tractography and functional MRI during phonological and control tasks. Thus, this study assessed white matter microstructure (i.e. hindrance-modulated orientational anisotropy) and macrostructure (i.e. tract volume) of language-related tracts and modeled induced electric field strength. While TMS did not produce group-level behavioral changes, stronger electric fields in the dominant hemisphere correlated with post-stimulation slowing. Only microstructure of the posterior arcuate fasciculus predicted improved control task efficiency after dominant-hemisphere stimulation. No white matter metrics predicted neural activation changes. These findings suggest that white matter properties weakly influence short-term behavioral and neural responses to IFG stimulation, possibly due to compensatory network mechanisms during distributed task engagement.}},
  author       = {{Thoma, Sophie}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{Does it Matter? Investigating the Association of White Matter Micro- and Macrostructure with Short-Term TMS Outcomes in the Language Network}},
  year         = {{2026}},
}