Theoretical analysis of transcranial Hall-effect stimulation based on passive cable model

Abstract

Transcranial Hall-effect stimulation (THS) is a new stimulation method in which an ultrasonic wave in a static magnetic field generates an electric field in an area of interest such as in the brain to modulate neuronal activities. However, the biophysical basis of simulating the neurons remains unknown. To address this problem, we perform a theoretical analysis based on a passive cable model to investigate the THS mechanism of neurons. Nerve tissues are conductive; an ultrasonic wave can move ions embedded in the tissue in a static magnetic field to generate an electric field (due to Lorentz force). In this study, a simulation model for an ultrasonically induced electric field in a static magnetic field is derived. Then, based on the passive cable model, the analytical solution for the voltage distribution in a nerve tissue is determined. The simulation results showthat THS can generate a voltage to stimulate neurons. Because the THS method possesses a higher spatial resolution and a deeper penetration depth, it shows promise as a tool for treating or rehabilitating neuropsychiatric disorders.

A new brain stimulation method: Noninvasive transcranial magneto–acoustical stimulation

“…The previous studies, in which the Maxwell equation combining the ultrasound and magnetic field was established and the distribution of electric field was obtained, predicted that TMAS can stimulate the nerve tissue, [10] in which, however, the action potentials in neuron models were not stim- Appendix A: Supplementary materials…”

“…where σ is the conductivity of the tissue with a typical value of the conductivity of tissue, 0.5 S/m; [10] B x is the intensity of the magnetostatic field; Ψ is the phase angle and obeys the following equation:…”

“…Meanwhile, the ratios of the mean amplitude between FUS and CTRL, and between FUS SMF are 2.38 and 2.36, which indicate that FUS can also modulate the oscillatory activities of brain, which is consistent with the result of previous FUS study. [10] To compare mean absolute amplitude between the TMAS and FUS and the increase in the amplitude of LFP is 1.45. Furthermore, the oscillatory activities of brain are significantly increased with TMAS, demonstrating that the TMAS can enhance the effect of FUS on the brain neuron modulation.…”

“…[6][7][8] In this paper, transcranial magneto-acoustical stimulation (TMAS) that was proposed by Norton in 2003 is developed for noninvasive brain neuromodulation. [9,10] FUS has the characteristics of noninvasive, high spatial resolution and high penetration depth. The mechanism of FUS is that the ultrasound-induced cavitation of these nanometric bilayer sonophores can induce a complex mechanoelectrical interplay that leads to excitation, primarily through the effect of currents induced by membrane capacitance change.…”