Parameter optimisation for mitigating somatosensory confounds during transcranial ultrasonic stimulation

Area of Science:

• Neuroscience
• Biophysics

Background:

• Transcranial ultrasonic stimulation (TUS) offers precise, non-invasive neuromodulation.
• Peripheral confounds, particularly somatosensory, are significant challenges in TUS.
• Somatosensory confounds have been overlooked despite increasing TUS intensity and frequency.

Purpose of the Study:

• Systematically characterize somatosensory co-stimulation during TUS.
• Identify conditions for effective mitigation of somatosensory confounds.
• Map the confound-parameter space for TUS.

Main Methods:

• Investigated dose-response effects of TUS.
• Analyzed pulse shaping characteristics.
• Examined transducer-specific parameters.

Main Results:

• Somatosensory confounds mitigated by avoiding scalp intensity peaks, spreading energy, ramping pulse envelopes, and using longer, lower-intensity pulses.
• Higher pulse repetition frequencies and fundamental frequencies reduced somatosensory effects.
• Preliminary evidence suggests particle displacement (strain) drives peripheral somatosensory co-stimulation.

Conclusions:

• Actionable strategies identified to minimize TUS-induced somatosensory confounds.
• Improved experimental control for TUS research and clinical interventions.
• Enhanced understanding of peripheral biophysical mechanisms in TUS.