Reaching Deep: Enhanced Brain Stimulation with Advanced H-Coils

Industry: The paper focuses on advancements in transcranial magnetic stimulation (TMS), a technique used in neuroscience and neurology for non-invasive brain stimulation. TMS is widely used for research and treatment of neurological and psychiatric disorders.

Challenge: Traditional TMS coils, like the figure-8 coil, have limitations in stimulating deep brain regions without causing unwanted cortical stimulation. This restricts the effectiveness of TMS for treating conditions that involve deeper brain structures.

How the GaGe Digitizer was used: The GaGe Digitizer was used to measure the electrical field induced by the TMS coils. The digitizer recorded the voltage differences captured by a dipole probe in the head model, allowing researchers to compute the electrical field strength and distribution.

Extraordinary Aspects of the Paper: The study introduces two new H-coils, H1 and H2, which are designed to stimulate deeper brain regions more effectively than the standard figure-8 coil. The H-coils can reach depths of 4-6 cm in the brain, compared to the 1.5 cm depth achieved by the figure-8 coil. This capability opens up new possibilities for TMS in treating a broader range of neurological disorders.

Equipment & Sensors Used:

GaGe Digitizer: Model and part number not specified, used for recording voltage measurements.

TMS Coils: H1-coil and H2-coil: Custom-designed for deep brain stimulation with flexible frames to fit various skull shapes. Figure-8 coil: Standard commercial Magstim coil with 7 cm internal loop diameters.

Field Measurement Probe: Two-wire dipole probe with 1.7 cm tip distance, used for measuring the electrical field in the head model.

Function Generator: Agilent Technologies Inc., used to drive the transducers.

Power Amplifier: 50-dB power amplifier from Electronic Navigation Industries.

3-D Positioning System: Computer-controlled system from Velmex Inc., used to move the probe within the head model.