Multi-locus transcranial magnetic stimulation—theory and implementation

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Journal Title
Journal ISSN
Volume Title
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Date
2018-07
Major/Subject
Mcode
Degree programme
Language
en
Pages
849-855
Series
Brain Stimulation, Volume 11, issue 4
Abstract
Background: Transcranial magnetic stimulation (TMS) is a non-invasive brain stimulation method: a magnetic field pulse from a TMS coil can excite neurons in a desired location of the cortex. Conventional TMS coils cause focal stimulation underneath the coil centre; to change the location of the stimulated spot, the coil must be moved over the new target. This physical movement is inherently slow, which limits, for example, feedback-controlled stimulation. Objective: To overcome the limitations of physical TMS-coil movement by introducing electronic targeting. Methods: We propose electronic stimulation targeting using a set of large overlapping coils and introduce a matrix-factorisation-based method to design such sets of coils. We built one such device and demonstrated the electronic stimulation targeting in vivo. Results: The demonstrated two-coil transducer allows translating the stimulated spot along a 30-mm-long line segment in the cortex; with five coils, a target can be selected from within a region of the cortex and stimulated in any direction. Thus, far fewer coils are required by our approach than by previously suggested ones, none of which have resulted in practical devices. Conclusion: Already with two coils, we can adjust the location of the induced electric field maximum along one dimension, which is sufficient to study, for example, the primary motor cortex.
Description
Keywords
Coil design, Electric field, Instrumentation, Multi-channel TMS, Multi-locus TMS, Transcranial magnetic stimulation
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Citation
Koponen, L M, Nieminen, J O & Ilmoniemi, R J 2018, ' Multi-locus transcranial magnetic stimulation—theory and implementation ', Brain Stimulation, vol. 11, no. 4, pp. 849-855 . https://doi.org/10.1016/j.brs.2018.03.014