Induction of Human Motor Cortex Plasticity by Theta Burst Transcranial Ultrasound Stimulation

Abstract

Objective: Transcranial ultrasound stimulation (TUS) is a promising noninvasive brain stimulation technique with advantages of high spatial precision and ability to target deep brain regions. This study aimed to develop a TUS protocol to effectively induce brain plasticity in human subjects. Methods: An 80-second train of theta burst patterned TUS (tbTUS), regularly patterned TUS (rTUS) with the same sonication duration, and sham tbTUS was delivered to the motor cortex in healthy subjects. Transcranial magnetic stimulation (TMS) was used to examine changes in corticospinal excitability, intracortical inhibition and facilitation, and the site of plasticity induction. The effects of motor cortical tbTUS on a visuomotor task and the effects of occipital cortex tbTUS on motor cortical excitability were also tested. Results: The tbTUS produced consistent increase in corticospinal excitability for at least 30 minutes, whereas rTUS and sham tbTUS produced no significant change. tbTUS decreased short-interval intracortical inhibition and increased intracortical facilitation. The effects of TMS in different current directions suggested that the site of the plastic changes was within the motor cortex. tbTUS to the occipital cortex did not change motor cortical excitability. Motor cortical tbTUS shortened movement time in a visuomotor task. Interpretation: tbTUS is a novel and efficient paradigm to induce cortical plasticity in humans. It has the potential to be developed for neuromodulation treatment for neurological and psychiatric disorders, and to advance neuroscience research.

Ultrasound Neuromodulation Reduces Demyelination in a Rat Model of Multiple Sclerosis

“…Although significant advances in the development of remyelinating drugs have been made recently, further work remains necessary to minimize side effects and alleviate safety concerns. In contrast, TUS is a safe and noninvasive form of neuromodulation, which is broadly applied in novel therapeutic methods for initial human studies [ 43 , 44 , 45 , 46 , 47 , 48 ]. Although increasingly being investigated, TUS is still in its early phases.…”

Ultrasound stimulation of the motor cortex during tonic muscle contraction

“…While the negative tUS results reported here mirror struggles some other investigators have shown when attempting to elicit measurable modulation of M1 by tUS, this was also a pilot study with small sample sizes (n = 8; n = 10). As such, clearer results may emerge with larger datasets or changes in methodology [ 103 ].…”

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