Comparison of the induced fields using different coil configurations during deep transcranial magnetic stimulation

• Published in: PloS one Vol. 12; no. 6; p. e0178422
• Main Authors: Lu, Mai, Ueno, Shoogo
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 06-06-2017; Public Library of Science (PLoS)
• Subjects: Assembly; Biology and Life Sciences; Brain; Brain - diagnostic imaging; Brain - physiopathology; Brain Mapping - methods; Care and treatment; Circularity; Coiling; Comparative analysis; Computer simulation; Cortex; Density; Design; Diagnosis; Disorders; Dosimetry; Electric fields; Electromagnetic Fields; Equipment Design; Evaluation; Excitation; Fluctuations; Flux density; Head; Humans; Impedance; Impedance method; Influence; Magnetic brain stimulation; Magnetic fields; Magnetic flux; Mathematical models; Medicine and Health Sciences; Mental Disorders; Motivation; Motivation - physiology; Nervous system diseases; Nervous System Diseases - diagnostic imaging; Nervous System Diseases - physiopathology; Neurological diseases; Penetration; Physical Sciences; Reinforcement; Research and Analysis Methods; Risk; Simulation; Studies; Therapeutic applications; Transcranial magnetic stimulation; Transcranial Magnetic Stimulation - instrumentation; Transcranial Magnetic Stimulation - methods
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0178422

Stimulation of deeper brain structures by transcranial magnetic stimulation (TMS) plays a role in the study of reward and motivation mechanisms, which may be beneficial in the treatment of several neurological and psychiatric disorders. However, electric field distributions induced in the brain by deep transcranial magnetic stimulation (dTMS) are still unknown. In this paper, the double cone coil, H-coil and Halo-circular assembly (HCA) coil which have been proposed for dTMS have been numerically designed. The distributions of magnetic flux density, induced electric field in an anatomically based realistic head model by applying the dTMS coils were numerically calculated by the impedance method. Results were compared with that of standard figure-of-eight (Fo8) coil. Simulation results show that double cone, H- and HCA coils have significantly deep field penetration compared to the conventional Fo8 coil, at the expense of induced higher and wider spread electrical fields in superficial cortical regions. Double cone and HCA coils have better ability to stimulate deep brain subregions compared to that of the H-coil. In the mean time, both double cone and HCA coils increase risk for optical nerve excitation. Our results suggest although the dTMS coils offer new tool with potential for both research and clinical applications for psychiatric and neurological disorders associated with dysfunctions of deep brain regions, the selection of the most suitable coil settings for a specific clinical application should be based on a balanced evaluation between stimulation depth and focality.