High-power dual-channel chamber for high-frequency magnetic neuromodulation

Area of Science:

• Neuroscience and Bioengineering
• Biomedical Engineering
• Magnetogenetics

Background:

• Novel methods like magnetogenetics and magnetoelectric stimulation use alternating magnetic fields to manipulate neural activity.
• Quantifying behavioral effects in freely moving subjects requires specialized equipment for precise magnetic field control.

Purpose of the Study:

• To develop and validate a dual-channel magnetic chamber for precise neural stimulation in freely moving mice.
• To enable rate-sensitive magnetothermal-genetic stimulation and other alternating magnetic field applications.

Main Methods:

• Designed a dual-channel magnetic chamber with optimized coil geometry for independent control of two spatially orthogonal magnetic fields.
• Utilized nominal frequencies of 50 and 550 kHz with high magnetic field strengths (88 and 12.5 mT) and resonant coil drives.
• Incorporated a liquid cooling system for sustained operation and an observation port with a camera for real-time behavioral monitoring.

Main Results:

• The system achieved high-amplitude magnetic fields across two distinct frequency channels with minimal interference (<1%).
• Demonstrated uniform magnetic field distribution (±10% across 94% of chamber volume) and ensured in vivo safety with limited temperature increase (<0.35℃/s).
• Validated frequency-selective heating rates (3.5℃/s and 1.5℃/s) using iron-oxide nanoparticles, with stable operation for 4 seconds.

Conclusions:

• A novel, high-frequency, high-power magnetic stimulation platform with independently controlled dual channels was developed.
• The platform supports real-time behavioral observation in freely moving animals, facilitating frequency-multiplexed stimulation strategies.
• This versatile tool advances magnetogenetics, neural circuit interrogation, and noninvasive stimulation research in neuroscience and bioengineering.