Brain Stimulation With cTMS

Researchers have developed a better way to manipulate a person's brain functioning. They have created a new type of transcranial magnetic stimulation (TMS) device (called controllable pulse width TMS or cTMS for short) that will allow rectangular pulse shapes of the magnetic fields. This device will enable researchers to control the width of the magnetic pulse that passes through the subjects skull. Regular TMS produces a much more unfocused magnetic field that stimulates a larger portion of the brain. It is less selective in its targeting ability and is more likely to stimulate unnecessary or undesirable brain regions. This new TMS on the other hand, may allow more targeted electrical activation or deactivation of specific areas of the brain. Using this new device may lead to fewer side effects and increased efficacy of TMS for disorders such as depression, pain management or schizophrenia. Researchers may also be able to use this technology to get an even better functionality map of the brain to find out what specific brain areas do.

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

"A novel transcranial magnetic stimulation (TMS) device with controllable pulse width (PW) and near-rectangular pulse shape (cTMS) is described. The cTMS device uses an insulated gate bipolar transistor (IGBT) with appropriate snubbers to switch coil currents up to 6 kA, enabling PW control from 5 micros to over 100 micros. The near-rectangular induced electric field pulses use 2%-34% less energy and generate 67%-72% less coil heating compared to matched conventional cosine pulses. CTMS is used to stimulate rhesus monkey motor cortex in vivo with PWs of 20 to 100 micros, demonstrating the expected decrease of threshold pulse amplitude with increasing PW. The technological solutions used in the cTMS prototype can expand functionality, and reduce power consumption and coil heating in TMS, enhancing its research and therapeutic applications."

Columbia University Medical Center

"Physiological response to TMS depends on the shape and width of the induced current pulses, however, existing TMS devices allow limited, if any, control over these parameters. The cTMS device induces near rectangular pulses with continuous control over pulse width and shape, allowing the pulses to be physiologically optimized for specific applications."

Angel V. Peterchev, Ph.D.

"These controllable pulse shape TMS (cTMS) devices could enable new methods for mapping neural parameters in vivo, as well as the optimization of stimulation paradigms for improved tolerability and stronger neuromodulatory effect in clinical applications"