Neuromodulation Effects of Ultrasound Stimulation Under Different Parameters on Mouse Motor Cortex

Objective: Although low-intensity transcranial ultrasound stimulation (TUS) enhances/suppresses neural oscillations and causes electroencephalography changes in the motor cortex, researchers have not clearly determined the manner in which the relative power and entropy of neural oscillations in the motor cortex vary with ultrasonic parameters, such as ultrasound intensity, stimulation duration (SD), and duty cycle. Methods: In this paper, we use the transcranial ultrasound of different parameters to stimulate the mouse motor cortex, cause tail muscle contraction and movement, and simultaneously record local field potentials (LFPs) in the mouse motor cortex. The relative power and entropy of the LFPs under different ultrasonic parameters are analyzed. Results: The relative power of the theta [4-8 Hz] frequency bands decreases with an increase in spatial-peak and pulse-average intensity (Isppa) at 0-0.5 s and 0.5-1 s; the relative power of the gamma [30-45 Hz] frequency bands increases with an increase in Isppa at 0-0.5 s and 0.5-1 s; the relative power each of the gamma [30-45 Hz] and high gamma [55-100 Hz] frequency bands increases with an increase in the SD at 0-0.5 s and 0.5-1 s; the entropy values decrease with increases in Isppa and SD at 0-0.5 s. Conclusion: The relative power and entropy of neural oscillations in the motor cortex can be modulated by TUS with different parameters, namely, ultrasound intensity and stimulation duration.