Multi-locus transcranial magnetic stimulation system for electronically targeted brain stimulation

Background: Transcranial magnetic stimulation (TMS) allows non-invasive stimulation of the cortex. In multi-locus TMS (mTMS), the stimulating electric field (E-field) is controlled electronically without coil movement by adjusting currents in the coils of a transducer. Objective: To develop an mTMS system that allows adjusting the location and orientation of the E-field maximum within a cortical region. Methods: We designed and manufactured a planar 5-coil mTMS transducer to allow controlling the maximum of the induced E-field within a cortical region approximately 30 mm in diameter. We developed electronics with a design consisting of independently controlled H-bridge circuits to drive up to six TMS coils. To control the hardware, we programmed software that runs on a field-programmable gate array and a computer. To induce the desired E-field in the cortex, we developed an optimization method to calculate the currents needed in the coils. We characterized the mTMS system and conducted a proof-of-concept motor-mapping experiment on a healthy volunteer. In the motor mapping, we kept the transducer placement fixed while electronically shifting the E-field maximum on the precentral gyrus and measuring electromyography from the contralateral hand. Results: The transducer consists of an oval coil, two figure-of-eight coils, and two four-leaf-clover coils stacked on top of each other. The technical characterization indicated that the mTMS system performs as designed. The measured motor evoked potential amplitudes varied consistently as a function of the location of the E-field maximum. Conclusion: The developed mTMS system enables electronically targeted brain stimulation within a cortical region.

Description

| openaire: EC/H2020/810377/EU//ConnectToBrain

Keywords

Coil, Electric field, Motor mapping, mTMS, Multi-locus, Transcranial magnetic stimulation, Transducer

DOI

10.1016/j.brs.2021.11.014

Citation

Nieminen , J O , Sinisalo , H , Souza , V H , Malmi , M , Yuryev , M , Tervo , A E , Stenroos , M , Milardovich , D , Korhonen , J T , Koponen , L M & Ilmoniemi , R J 2022 , ' Multi-locus transcranial magnetic stimulation system for electronically targeted brain stimulation ' , Brain Stimulation , vol. 15 , no. 1 , pp. 116-124 . https://doi.org/10.1016/j.brs.2021.11.014

Permanent link to this item

https://urn.fi/URN:NBN:fi:aalto-2021121510774

Collections

[article-cris] Perustieteiden korkeakoulu / SCI

Show all metadata