Simulation and Design of a Rodent-Specific Transcranial Magnetic Stimulation Coil Based on the Principle of Temporal Interference

Transcranial magnetic stimulation (TMS) is a noninvasive and painless treatment for psychiatric disorders. The basic mechanisms of TMS are understood primarily from studies of rodents. However, due to the relatively small brain size of rodents, the current commercially available animal coils are poorly focusing, leading to an inability to stimulate specific brain regions. To address the above issues, a magnetic stimulation coil is designed for rodents based on the principle of temporal interference and the relationships between the stimulation effect of temporal interference magnetic stimulation (TI-TMS) and the coil parameters are also explored. The result found that the stimulus intensity, stimulus depth, and focusing of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Pi $ </tex-math></inline-formula>-core coils are enhanced by 61.8%, 52.3%, and 32.5% compared with the rTMS miniaturized eight-figure coil. A novel discharge circuit for TI-TMS has been designed in this article and the feasibility is verified by saline experiment. The frequency and amplitude of the circuit can be controlled.