A transcranial magnetic stimulator inducing near-rectangular pulses with controllable pulse width (cTMS).

Area of Science:

• Biomedical Engineering
• Neuroscience
• Medical Devices

Background:

• Transcranial magnetic stimulation (TMS) is a non-invasive brain stimulation technique.
• Conventional TMS devices often use cosine pulse shapes, which can be energy-intensive and generate significant heat.
• Optimizing TMS parameters like pulse width (PW) is crucial for improving efficacy and safety.

Purpose of the Study:

• To describe a novel transcranial magnetic stimulation (TMS) device with controllable pulse width (PW) and a near-rectangular pulse shape (cTMS).
• To evaluate the energy efficiency and coil heating characteristics of the cTMS device compared to conventional methods.
• To demonstrate the in vivo efficacy of the cTMS device in stimulating the motor cortex.

Main Methods:

• Development of a cTMS device utilizing insulated gate bipolar transistors (IGBTs) for high-current switching (up to 6 kA).
• Implementation of PW control ranging from 5 to over 100 microseconds.
• Comparison of energy consumption and coil heating between cTMS and conventional cosine pulses.
• In vivo stimulation of the rhesus monkey motor cortex using the cTMS device.

Main Results:

• The cTMS device achieved PW control from 5 to over 100 microseconds.
• Near-rectangular pulses required 2%-34% less energy and generated 67%-72% less coil heating compared to conventional cosine pulses.
• In vivo experiments showed a decrease in threshold pulse amplitude with increasing PW during motor cortex stimulation.

Conclusions:

• The novel cTMS device offers significant improvements in energy efficiency and reduced coil heating.
• The controllable PW and near-rectangular pulse shape enhance the functionality of TMS devices.
• These advancements hold promise for expanding the research and therapeutic applications of TMS.