An Exploration of the Electrocorticogram Signatures Evoked by Ultrasound Thalamus Stimulation Under Isoflurane Anesthesia in Rats
Zhijie Wang, Zhiwei Li, Yingwei Li, Gengsheng Mao, Xiaoli Li, Zhenhu Liang
IEEE Transactions on Biomedical Engineering 2025 · 10.1109/tbme.2025.3555648
Abstract
Objective The transcranial ultrasound stimulation (TUS) on the thalamus can indirectly induce cortical response. Studies have shown that general anesthetic induced unconsciousness is related to interruption of thalamocortical connectivity. However, the neural mechanism of how anesthesia levels influence cortical responses during ultrasound thalamus stimulation has never been explored yet. And it remains unknown what cortical responses signatures are evoked by ultrasound thalamus stimulation under different anesthesia levels. Methods We recorded multichannel electrocorticogram (ECoG) evoked by ultrasound thalamus stimulation of rats at various isoflurane concentrations (i.e., 0.5%, 1.0%, 1.5%, and 2.0% (v/v)). We analyzed ECoG signatures in temporal, spatial, and frequency domains by using the ultrasound-evoked potentials (UEPs), omega complexity (OC), and phase amplitude coupling (PAC), respectively. Results The pattern of UEPs was influenced by the anesthesia level, and the response amplitude of UEPs increased with the increase in anesthesia level (0.5% vs. 1.0% and 1.5% (v/v), p Conclusion The cortical response induced by ultrasound thalamus stimulation is related to the anesthesia level. TUS on the thalamus combined with ECoG (TUS-ECoG) may be a potential non-invasive neuromodulation approach for understanding consciousness. Significance This work supplied further implications on the neuromodulatory mechanisms and evaluative applications of TUS under general anesthesia.
Abstract via europepmc.
Exposures
Exposure 1: Thalamus TUS under isoflurane
Target: thalamus — “the thalamus”
Device: Olympus / Panametrics · Olympus · V301-SU (driven by JL-JLCJ-02, Jielian Tech) ✓
| Waveform | pulsed | |
|---|---|---|
| Fundamental frequency (kHz) | 500 | ✓✓✓ |
| Pulse duration (ms) | not reportedimplied by duty cycle ÷ PRF: 0.4 ms (not stated by the paper) | ⚑ |
| Pulse repetition frequency (Hz) | 1,000 | ✓✓✓ |
| Duty cycle (%) | 40 | ✓✓✓ |
| Sonication duration (s) | 0.05 | ✓✓✓⚑ |
| Free-field pressure (kPa) | not reported | |
|---|---|---|
| Free-field Isppa (W/cm²) | not reported | |
| Free-field Ispta (W/cm²) | not reported | |
| In-situ estimate | not reported | |
| In-situ pressure (kPa) | not reported | |
| In-situ Isppa (W/cm²) | 2.3 | ✓✓✓ |
| In-situ Ispta (W/cm²) | not reported |
Trigger frequency 3 ± Δt s (Δt random 0-1 s), stimulation duration 50 ms, PRF 1 kHz, duty cycle 40%, 500 kHz; five minutes of stimulated ECoG recorded at each of four isoflurane concentrations (2.0, 1.5, 1.0, 0.5%).
Flags from extraction
n_subjects— Number of rats read from a figure legend and results text ('nine rats'); total enrolled not otherwise stated.exposures[0].timing.pulse_duration_ms— Pulse duration not stated; paper gives stimulation duration 50 ms, PRF 1 kHz, DC 40%.exposures[0].unspecified_domain.isppa_w_cm2— Isppa measured by hydrophone with a small slice of rat skull in front of the collimator; unsure whether this counts as in situ, left unspecified.exposures[0].timing.sonication_duration_s— Stimulation duration (SD) 50 ms interpreted as sonication length; repeated at trigger frequency 3 s plus random 0-1 s.