Transcranial Focused Ultrasound Neuromodulation of Voluntary Movement-Related Cortical Activity in Humans

Abstract

Transcranial focused ultrasound (tFUS) is an emerging non-invasive brain stimulation tool for safely and reversibly modulating brain circuits. The effectiveness of tFUS on human brain has been demonstrated, but how tFUS influences the human voluntary motor processing in the brain remains unclear. Methods: We apply low-intensity tFUS to modulate the movement-related cortical potential (MRCP) originating from human subjects practicing a voluntary foot tapping task. 64channel electroencephalograph (EEG) is recorded concurrently and further used to reconstruct the brain source activity specifically at the primary leg motor cortical area using the electrophysiological source imaging (ESI). Results: The ESI illustrates the ultrasound modulated MRCP source dynamics with high spatiotemporal resolutions. The MRCP source is imaged and its source profile is further evaluated for assessing the tFUS neuromodulatory effects on the voluntary MRCP. Moreover, the effect of ultrasound pulse repetition frequency (UPRF) is further assessed in modulating the MRCP. The ESI results show that tFUS significantly increases the MRCP source profile amplitude (MSPA) comparing to a sham ultrasound condition, and further, a high UPRF enhances the MSPA more than a low UPRF does. Conclusion: The present results demonstrate the neuromodulatory effects of the low-intensity tFUS on enhancing the human voluntary movement-related cortical activities evidenced through the ESI imaging. Significance: This work provides the first evidence of tFUS enhancing the human endogenous motor cortical activities through excitatory modulation.

Transcranial Focused Ultrasound Neuromodulation: A Review of the Excitatory and Inhibitory Effects on Brain Activity in Human and Animals

“…Through ESI, the results showed that tFUS modulates MRCP source dynamics with high spatiotemporal resolutions and significantly increases the MRCP source profile amplitude (MSPA), and further, a high PRF enhances the MSPA outperforms a low UPRF does. This study provides the first evidence that tFUS enhances human endogenous motor cortical activities through excitatory modulation ( Yu et al, 2020 ).…”

“…As discussed by the authors, the different findings may be caused by stimulation parameters and other methodological factors. Yu et al (2020) demonstrated the neuromodulatory effects of low-intensity tFUS on human voluntary movement-related cortical potential (MRCP). Through ESI, the results showed that tFUS modulates MRCP source dynamics with high spatiotemporal resolutions and significantly increases the MRCP source profile amplitude (MSPA), and further, a high PRF enhances the MSPA outperforms a low UPRF does.…”

“…The studies of Fomenko et al (2020) reported that tFUS targeting at the motor cortex displayed inhibitory effects on cortical excitability, but the effects on SICI were inconsistent. Furthermore, other studies have reported heterogeneous effects of FUS targeting on the motor cortex, demonstrating increased cortical excitability or the amplitude of MEPs after prolonged sonication ( Gibson et al, 2018 ; Yu et al, 2020 ).…”

Mathematical Model of Ultrasound Attenuation With Skull Thickness for Transcranial-Focused Ultrasound

“…The sound pressure was chosen based on the literature on tFUS neuromodulation. For example, Yu et al (2020) select a sound pressure of 0.8092 MPa in their experiment. Sound pressures of 0.5, 1, 2, and 4 MPa are used in another study ( Gaur et al, 2020 ).…”

Low Intensity Focused Ultrasound for Non-invasive and Reversible Deep Brain Neuromodulation—A Paradigm Shift in Psychiatric Research

“…Using a simultaneous ultrasound and TMS paradigm, LIFU to the motor cortex ( Table 1 ) reduced the amplitude of TMS-evoked motor evoked potentials and attenuated intracortical facilitation ( 31 ). Conversely, a study using concurrent LIFU-EEG ( Table 1 ), found evidence that LIFU enhanced the movement-related cortical potential ( 33 ). A novel theta burst patterned LIFU protocol was also recently introduced that produced a consistent increase in motor cortical excitability ( 35 ).…”