Modular pulse synthesizer for transcranial magnetic stimulation with fully adjustable pulse shape and sequence.

Area of Science:

• Neuroscience
• Biomedical Engineering
• Electrical Engineering

Background:

• The temporal shape of transcranial magnetic stimulation (TMS) pulses critically impacts neuron activation, neuromodulation efficacy, and sensory perception.
• Current TMS technology offers a limited repertoire of pulse shapes, hindering flexible waveform control and advanced stimulation paradigms.
• Existing methods for flexible pulse shaping face limitations due to semiconductor stress and inability to generate smooth electric fields.

Purpose of the Study:

• To introduce a novel modular pulse synthesizer (MPS) technology for flexible, high-power TMS pulse generation.
• To enable user-defined electric field shapes and rapid pulse sequences with high output quality in TMS.
• To overcome limitations of conventional TMS devices, including restricted waveform control and capacitive artifacts.

Main Methods:

• Development of a modular power electronics architecture that distributes high-power, high-speed switching across multiple identical modules.
• Utilization of semiconductor devices with lower voltage and current ratings, managed by distributed switching at several hundred kilohertz.
• Implementation of optional symmetric differential coil driving to maintain constant coil potential and minimize artifacts.

Main Results:

• The MPS technology can flexibly generate high-power TMS pulses (peak ~4000 V, ~8000 A) with user-defined electric field shapes.
• It synthesizes virtually any pulse shape with fine electric field quantization (~17% granularity) and ~300 kHz bandwidth.
• The system enables rapid sequences of pulses with high output quality and prevents capacitive artifacts in sensitive recording amplifiers.

Conclusions:

• The MPS TMS technology provides unprecedented flexibility in TMS waveform control, overcoming previous limitations.
• This advancement facilitates the optimization of stimulation paradigms for enhanced brain function probing and more effective neuromodulation.
• The technology expands the available parameter space for TMS users, paving the way for sophisticated neuroscience research and clinical applications.