Simulation of controllable pulse parameter transcranial magnetic stimulation in realistic head model with morphologically-accurate cortical neurons

Transcranial magnetic stimulation (TMS) enables non-invasive modulation of brain activity with both clinical and research applications, but fundamental questions remain about the neural types and elements it activates and how stimulation parameters affect the neural response. We integrated detailed neuronal models with TMS-induced electric fields in the human head to quantify the effects of TMS on cortical neurons. TMS activated with lowest intensity layer 5 pyramidal cells at their intracortical axonal terminations in the superficial gyral crown and lip regions. Layer 2/3 pyramidal cells and inhibitory basket cells may be activated too, whereas direct activation of layers 1 and 6 was unlikely. Neural activation was largely driven by the field magnitude, contrary to theories implicating the field component normal to the cortical surface. Varying the induced current's direction caused a waveform-dependent shift in the activation site and provided a mechanistic explanation for experimentally observed differences in thresholds and latencies of muscle responses. This biophysically-based simulation provides a novel method to elucidate mechanisms and inform parameter selection of TMS and other forms of cortical stimulation.

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Simulation of transcranial magnetic stimulation in head model with morphologically-realistic cortical neurons

Brain Stimulation ◽

10.1016/j.brs.2019.10.002 ◽

2020 ◽

Vol 13 (1) ◽

pp. 175-189 ◽

Cited By ~ 30

Author(s):

Aman S. Aberra ◽

Boshuo Wang ◽

Warren M. Grill ◽

Angel V. Peterchev

Keyword(s):

Transcranial Magnetic Stimulation ◽

Cortical Neurons ◽

Magnetic Stimulation ◽

Head Model

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Transcranial magnetic stimulation: a new tool in the fight against depression

Dialogues in Clinical Neuroscience ◽

10.31887/dcns.2002.4.1/lgrunhaus ◽

2002 ◽

Vol 4 (1) ◽

pp. 93-103

Keyword(s):

Transcranial Magnetic Stimulation ◽

Cortical Neurons ◽

Magnetic Stimulation ◽

Cortical Excitability ◽

Central Nervous System Function ◽

Technical Parameters ◽

Antidepressant Effects ◽

Health And Disease ◽

Nervous System Function ◽

Basic Concepts

Since its introduction to the clinical realm in 1985, transcranial magnetic stimulation (TMS) has rapidly developed into a tool for exploring central nervous system function in both health and disease. The antidepressant effects of TMS were initially observed in 1993. Since then, a solid body of evidence has accumulated suggesting antidepressant effects for both slow TMS (sTMS) and repetitive TMS (rTMS). This review is divided into four parts. First, it addresses the basic concepts governing TMS, and then, second, it discusses the technical parameters involved in administering TMS. Knowledge of these parameters is necessary for understanding how TMS is administered, and how manipulation of the technique impacts on the results obtained. Third, we review the most relevant studies on the antidepressant effects of sTMS and rTMS published to date. Finally, we discuss cortical excitability and how the understanding of this basic neurophysiological function of cortical neurons can be used for monitoring the effects of TMS. In our discussion, we conclude that the time has arrived for TMS to be offered to depressed patients as a treatment.

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