Investigating the Role of Coil Designs and Anatomical Variations in Cerebellar TMS

Abstract

Transcranial magnetic stimulation (TMS) is a non-invasive neuromodulation technique that is used for treating various neurological disorders such as major depressive disorder. TMS has been gaining popularity in the field of neurostimulation of the cerebellum, since the cerebellum is a complex structure connected with almost the entire central nervous system and TMS has promise for non-invasively probing cerebellar function. Recent studies have discovered that the cerebellum plays an important role not only in motor planning and behavior but also in the cognitive domain. However, few studies have explored how different coil designs and anatomical variations affect the effectiveness of cerebellar TMS. Therefore, in this paper, we investigated the effects of cerebellar TMS with different coil designs positioning on several locations. Finite-element modeling was conducted with Figure-8 coil and D-B80 coil. Each coil was positioned in the center, 1 and 3 cm to the left of center of the cerebellum, and all the locations were tangential to the scalp at a distance of 5 mm. Furthermore, 50 MRI derived head models were used in the computer modeling to examine how anatomical variations affect the distribution and intensity of electric field in cerebellar TMS.

Review on biophysical modelling and simulation studies for transcranial magnetic stimulation

“…In summary, various studies have investigated inter-subject variability of the induced EF ranging from a few to up to 50 subjects (Bijsterbosch et differences (Opitz et al 2011, Bijsterbosch et al 2012, Janssen et al 2013. Also, the EF variability may be different according to the targeted brain part and population segment (Bijsterbosch et al 2012, Zhong et al 2019. In the studies reviewed in this and other subsections, adults have been the predominant population segment (figure 5(b)), and the elderly and youth populations are almost unexplored.…”

“…The variability was larger in other regions, which had complicated, variable, and distinct folding patterns between individuals. Zhong et al (2019) demonstrated the difference between two coils (conventional figureof-eight coil and the coil used for deep brain stimulation) targeting the cerebellum in 50 subjects using the FEM. The maximum induced EF strength had a normalised standard deviation ranging from 20 to 34% among subjects in the target regions.…”

“…The variability of the maximum EF strength was minor at the motor or sensory areas where the sulcus was approximately in the same direction in all individuals. The variability was larger in other regions, which had complicated, variable, and distinct folding patterns between individuals Zhong et al (2019). demonstrated the difference between two coils (conventional figureof-eight coil and the coil used for deep brain stimulation) targeting the cerebellum in 50 subjects using the FEM.…”

Numerical Analysis of Transcranial Magnetic Stimulation Application in Patients With Orofacial Pain

“…This model simplifies the material and geometric characteristics of a human head. A logical trend in rTMS modeling are so-called anatomically accurate models [15]. Commercially available anatomical models based on MRI image segmentation are especially popular today [16] [17] [18].…”

Transcranial magnetic stimulation: Coil modeling and analysis for activation of cortical neurons

“…In computer modeling, a current of 5000 A is applied to TMS coils at a frequency of 2.5 kHz for output comparable to a conventional stimulator [55]. For coils with double windings (QBC, FOE coil, and their variant), the current direction in both windings is opposite to each other.…”