Effects of Transcranial Ultrasound Stimulation on Neural Electrical Activity in the Paraventricular Thalamus of Rats Under Etomidate Anesthesia

Background: Transcranial ultrasound stimulation (TUS) has been shown to modulate recovery from propofol anesthesia. Etomidate is also widely used as an anesthetic in clinical practice. Therefore, further investigation is needed to clarify whether TUS modulates thalamic neural electrical activity under etomidate anesthesia. Methods: In this study, we applied TUS to the paraventricular nucleus of the thalamus (PVT) in etomidate-anesthetized rats. Local field potentials (LFPs) from the PVT and electromyography (EMG) signals from cervical muscles were recorded to analyze anesthesia recovery time, time-frequency characteristics, power spectral density, and sample entropy (SampEn). Results: The recovery time from anesthesia was significantly shorter in the TUS group than in the sham group. TUS also induced significant changes in LFPs metrics during emergence, including: a significant decrease in mean absolute power (MAP) in the 4–8 Hz band and increases in the 30–60 Hz, 60–100 Hz, 100–140 Hz, and 140–200 Hz bands; a reduction in relative power (RP) in the 4–8 Hz band and elevations in the 30–60 Hz and 60–100 Hz bands; and a significant increase in SampEn across the 1–200 Hz frequency spectrum. Conclusion: TUS effectively modulated the relative power, mean absolute power, and SampEn of LFPs during the transition from anesthetized to awake states in etomidate-anesthetized rats.