Repetitive transcranial magnetic stimulation (rTMS) is attracting attention as a new treatment technique for brain lesions, and many animal studies showing its effects have been reported. However, the findings of animal application researches cannot directly represent the effects of rTMS in human, mainly due to size difference and mechanistic characteristics of rTMS. Therefore, the authors purposed to develop a mouse rTMS to simulate clinical application and to confirm. Firstly, a virtual head model was created according to magnetic resonance images of murine head. Then, simulations of rTMS stimulation with different coils were performed on the murine head phantom, and an rTMS device for mice was fabricated based on the optimal voltage conditions. Lastly, strengths of magnetic fields generated by the two rTMS devices, for human (conventional clinical use) and mouse (newly fabricated), were measured in air and on mouse head and compared. Resultantly, the magnetic field intensity generated by coil of mouse was lower than human’s (p < 0.01), and no differences were found between the predicted simulation values and the measured intensity in vivo (p > 0.05). Further in vivo researches using miniaturized rTMS devices for murine head should be followed to be more meaningful for human.

Transcranial magnetic stimulation (TMS) is a non-invasive neurom odulation technique used to treat various neurological disorders, including major depression. Since the cerebellum is a complex structure connected almost throughout the central nervous system, TMS has gained popularity in the field of cerebellar neurostimulation and promises to stimulate cerebellar activity non-invasively. The TMS coil structure and material play significant roles in achieving the focality of the coil. However, few studies have proposed various structures of solid coils, such as figure-of-eight (FOE) and butterfly-shaped coils to increase the focality of the coil. However, it is observed that there is always a trade-off between the field intensity and the temperature of the coil. In this study, new designs of TMS coils were proposed to reduce the temperature of the coil without significantly reducing the magnetic field intensity. Finite-element simulation tools such as ANSYS Maxwell ® and FEMTET® were used to simulate the field intensity and thermal analysis. The proposed design included hollow coils, double-layered hollow coils, and enamel-layered hollow coils.

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