Effective Ultrasonic Stimulation in Human Peripheral Nervous System.

Area of Science:

• Biomedical Engineering
• Neuroscience
• Acoustics

Background:

• Noninvasive stimulation of excitable cells using low-intensity ultrasound is promising.
• Identifying effective ultrasound parameters for stimulation has been challenging due to variations in transducers and frequencies.
• Stimulated tissue volume differences complicate the evaluation of ultrasound parameters.

Purpose of the Study:

• To control for differences in stimulated volumes and evaluate effective ultrasound parameters for stimulating excitable cells.
• To determine the impact of ultrasound frequency on stimulating the human peripheral nervous system.
• To compare the efficacy of low versus high ultrasound frequencies in eliciting tactile and nociceptive responses.

Main Methods:

• Stimulation of the human peripheral nervous system using a single ultrasound transducer.
• Operation of the transducer across a range of frequencies (300 kHz and 900 kHz).
• Matching stimulated volumes with an acoustic aperture to control for spatial differences.

Main Results:

• Low frequencies (300 kHz) were significantly more effective in generating tactile and nociceptive responses compared to high frequencies (900 kHz).
• The observed effect of ultrasound frequency was consistent across tested pressures and stimulus types (continuous and pulsed).
• Both tactile and nociceptive responses were stronger at lower frequencies.

Conclusions:

• Ultrasonic stimulation of excitable cells is more potent at lower frequencies.
• The enhanced effect at low frequencies is likely due to mechanical forces, not thermal effects.
• This study provides crucial guidance for selecting transducer hardware for effective ultrasonic stimulation of the peripheral nervous system.