The influence of sensory potentials on transcranial magnetic stimulation - Electroencephalography recordings

Nahian S Chowdhury; Nigel C Rogasch; Alan K I Chiang; Samantha K Millard; Patrick Skippen; Wei-Ju Chang; Katarzyna Bilska; Emily Si; David A Seminowicz; Siobhan M Schabrun

doi:10.1016/j.clinph.2022.05.015

The influence of sensory potentials on transcranial magnetic stimulation - Electroencephalography recordings

Clin Neurophysiol. 2022 Aug:140:98-109. doi: 10.1016/j.clinph.2022.05.015. Epub 2022 Jun 11.

Affiliations

¹ Center for Pain IMPACT, Neuroscience Research Australia, Sydney, New South Wales, Australia; University of New South Wales, Sydney, New South Wales, Australia. Electronic address: n.chowdhury@neura.edu.au.
² Discipline of Psychiatry, Adelaide Medical School, University of Adelaide, Adelaide, South Australia, Australia; Hopwood Centre for Neurobiology, Lifelong Health Theme, South Australian Health and Medical Research Institute, Adelaide, South Australia, Australia; Turner Institute for Brain and Mental Health, School of Psychological Sciences and Monash Biomedical Imaging, Monash University, Melbourne, Victoria, Australia.
³ Center for Pain IMPACT, Neuroscience Research Australia, Sydney, New South Wales, Australia.
⁴ Center for Pain IMPACT, Neuroscience Research Australia, Sydney, New South Wales, Australia; University of New South Wales, Sydney, New South Wales, Australia.
⁵ Department of Neural and Pain Sciences, University of Maryland School of Dentistry, Baltimore, MD, 21201, United States; Center to Advance Chronic Pain Research, University of Maryland Baltimore, Baltimore, MD 21201, United States.

PMID: 35760007
DOI: 10.1016/j.clinph.2022.05.015

Abstract

Objective: It remains unclear to what extent Transcranial Magnetic Stimulation-evoked potentials (TEPs) reflect sensory (auditory and somatosensory) potentials as opposed to cortical excitability. The present study aimed to determine; a) the extent to which sensory potentials contaminate TEPs using a spatially-matched sham condition, and b) whether sensory potentials reflect auditory or somatosensory potentials alone, or a combination of the two.

Methods: Twenty healthy participants received active or sham stimulation, with the latter consisting a sham coil click combined with scalp electrical stimulation. Two additional conditions i) electrical stimulation and ii) auditory stimulation alone, were included in a subset of 13 participants.

Results: Signals from active and sham stimulation were correlated in spatial and temporal domains > 55 ms post-stimulation. Relative to auditory or electrical stimulation alone, sham stimulation resulted in a) larger potentials, b) stronger correlations with active stimulation and c) a signal that was not a linear sum of electrical and auditory stimulation alone.

Conclusions: Sensory potentials can confound interpretations of TEPs at timepoints > 55 ms post-stimulation. Furthermore, TEP contamination cannot be explained by auditory or somatosensory potentials alone, but instead reflects a non-linear interaction between both.

Significance: Future studies may benefit from controlling for sensory contamination using spatially-matched sham conditions, and which consist of combined auditory and somatosensory stimulation.

Keywords: Electroencephalography; Sensory-evoked potentials; Sham stimulation; TMS-EEG; Transcranial magnetic stimulation.

MeSH terms

Electroencephalography* / methods
Evoked Potentials / physiology
Evoked Potentials, Motor / physiology
Healthy Volunteers
Humans
Scalp
Transcranial Magnetic Stimulation* / methods