Trade-off between stimulation focality and the number of coils in multi-locus transcranial magnetic stimulation

Nurmi, Samuel; Karttunen, Jere; Souza, Victor H.; Ilmoniemi, Risto J.; Nieminen, Jaakko O.

doi:10.1088/1741-2552/ac3207

Cited by 16 publications

(14 citation statements)

References 27 publications

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“…For example, the 30-mm targeting range in the cortex can be made larger or E-field focality can be made adjustable. To expand the cortical region within which the E-field can be targeted beyond the 30-mm-diameter region demonstrated in this study, one may (1) develop a transducer with more than five coils [9,40], (2) reduce the desired E-field focality to design a five-coil transducer with a wider control region [40], or (3) implement a transducer that follows the head curvature [40]. To study interhemispheric communication in motor networks for the study of motor control [41], one may use the 5-coil transducer on one hemisphere while stimulating the contralateral hemisphere with a separate figureof-eight coil.…”

Section: Discussionmentioning

confidence: 99%

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

Nieminen

Sinisalo

Souza

et al. 2021

Preprint

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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.

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Section: Discussionmentioning

confidence: 99%

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

Nieminen

Sinisalo

Souza

et al. 2021

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…For example, the 30-mm targeting range in the cortex can be made larger or E-field focality can be made adjustable. To expand the cortical region within which the E-field can be targeted beyond the 30-mm-diameter region demonstrated in this study, one may (1) develop a transducer with more than five coils [ 9 , 40 ], (2) reduce the desired E-field focality to design a five-coil transducer with a wider control region [ 40 ], or (3) implement a transducer that follows the head curvature [ 40 ]. To study interhemispheric communication in motor networks for the study of motor control [ 41 ], one may use the 5-coil transducer on one hemisphere while stimulating the contralateral hemisphere with a separate figure-of-eight coil.…”

Section: Discussionmentioning

confidence: 99%

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

et al. 2022

Self Cite

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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.

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“…Previous research exploring rTMS protocols revealed its strength for treatmentresistant depression symptomology, lessening chronic orofacial pains, and obsessive-compulsive disorder, among several other ailments [22][23][24]. A hallmark characteristic of rTMS is its depthfocality tradeoff, which results in stimuli applied to non-targeted brain structures when probing deeper regions [25,26]. This feature seems to suggest that rTMS may prove highly efficacious in repairing dysfunctional neural networks (via activity-dependent modulation of synaptic plasticity), particularly in TBI patients with diffuse axonal injury.…”

Section: Repetitive Transcranial Magnetic Stimulationmentioning

confidence: 99%

Neurostimulation for Traumatic Brain Injury: Emerging Innovation

Diaz¹,

Root²,

Beneke³

et al. 2023

OBM Neurobiol

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Traumatic brain injury (TBI) is a significant source of brain deficit and death among neurosurgical patients, with limited prospects for functional recovery in the cases of moderate-to-severe injury. Until now, the relevant body of literature on TBI intervention has focused on first-line, invasive treatment options (namely craniectomy and hematoma evacuation) with underwhelming focus on non-invasive therapies following surgical stabilization. Recent advances in our understanding of the impaired brain have encouraged deeper investigation of neurostimulation strategies, owed largely to its demonstrated livening of damaged neural circuitry and capacity to stabilize erratic network activity. The objective of the present study is to provide a scoping review of new knowledge in neurostimulation published in the PubMed, Scopus, and Google Scholar databases from inception to November 2022. We critically assess and appraise the available data on primary neurostimulation delivery techniques, with marked emphasis on restorative opportunities for accessory neurostimulation in the interdisciplinary care of moderate-to-severe TBI (msTBI) patients. These data identify two primary future directions: 1) to relate obtained gain-of-function outcomes to hemodynamic and histological changes and 2) to develop a clearer understanding of neurostimulation efficacy, when combined with pharmacologic interventions or other modulatory techniques, for complex brain insult.

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Trade-off between stimulation focality and the number of coils in multi-locus transcranial magnetic stimulation

Cited by 16 publications

References 27 publications

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

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

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

Neurostimulation for Traumatic Brain Injury: Emerging Innovation

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