Solving the orientation specific constraints in transcranial magnetic stimulation by rotating fields

Area of Science:

• Neuroscience
• Biophysics
• Biomedical Engineering

Background:

• Transcranial Magnetic Stimulation (TMS) shows promise for neurological and psychiatric disorders, including depression.
• Current TMS applications are limited by inter-subject variability and lack of accessible model systems.
• Angular sensitivity of TMS contributes to these limitations, hindering precise and reliable stimulation.

Purpose of the Study:

• To develop a TMS technique that overcomes angular sensitivity.
• To improve the reliability and effectiveness of TMS for brain stimulation.
• To enable TMS application in challenging model systems and human subjects.

Main Methods:

• Rotation of the stimulating magnetic field by superposing fields from two orthogonally positioned coils with a time phase shift.
• Development of rotating field TMS (rfTMS).
• Testing rfTMS on cultured hippocampal networks and rat motor cortex.

Main Results:

• rfTMS efficiently stimulates neuronal systems previously difficult to excite magnetically.
• rfTMS overcomes the orientation dependence of standard TMS.
• rfTMS enables optimal targeting in human subjects, even in regions with undetermined or absent preferred axonal orientation.

Conclusions:

• Rotating field TMS (rfTMS) effectively addresses the angular sensitivity of standard TMS.
• rfTMS enhances inter-subject reliability and expands the utility of TMS in research and clinical applications.
• rfTMS opens new possibilities for studying brain disorders and developing targeted neuromodulation therapies.