The mouse motor cortex stimulation via non-invasive temporal interference transcranial focused ultrasound with microbubbles
Jie Jin, Xinze Liu, Zhenxiang Ji, Chenxuan Wu, Yuting Han, Quanrong Jing, Jian Zhang, Wei Li, Tianyi Yan, Hui Jing, Dingjie Suo
Ultrasonics Sonochemistry 2025 · 10.1016/j.ultsonch.2025.107561
Abstract
Transcranial focused ultrasound (tFUS) has emerged as an innovative brain stimulation technology that uniquely integrates three characteristics: (a) non-invasive energy delivery, (b) submillimeter-scale spatial precision, and (c) effective penetration through cranial barriers to reach subcortical structures. Previous studies have shown that microbubbles (MBs) could amplify the mechanical effects of ultrasound, and the utilization of temporal interference ultrasound excitation effectively lowers cavitation thresholds. In this study, tFUS is applied to the motor cortex of both normal mice and MB-injected mice. Electromyography (EMG) recordings are utilized to analyze the effects of temporal interference (TI) ultrasound and single-frequency ultrasound stimulation on contralateral limb movements in mice. A hybrid model integrating the Gilmore-Akulichev-Zener (GAZ) model with nonlinear lipid membrane dynamics is developed, and numerical simulations of microbubble (MB) dynamics are performed to calculate the scattered pressure exerted by MBs on neurons. The study demonstrated that temporal interference ultrasound combined with MBs could increase the success rate of motor responses. The potential mechanism could be temporal interference ultrasound combined with MBs generate higher scattered pressures. The results demonstrated that temporal interference ultrasound combined with MBs could enhance neuronal activity in the Central Nervous System, enabling a highly specific method to increase the efficiency of tFUS stimulation.
Abstract via europepmc.
Exposures
Exposure 1: Single-frequency 1 MHz tFUS without microbubbles
Target: primary motor cortex — “right M1 region / mouse motor cortex”
Device: not reported
| Waveform | pulsed | |
|---|---|---|
| Fundamental frequency (kHz) | 1,000 | ✓✓✓ |
| 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) | 0.4 | ✓✓✓ |
| 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) | 330, 580swept | ✓✓✓ |
| In-situ Isppa (W/cm²) | not reported | |
| In-situ Ispta (W/cm²) | not reported |
400 ms stimulation, 3.6 s interstimulus interval, 1000 Hz PRF, 40 % DC; tested with and without a single 60 ul tail-vein injection of SonoVue microbubbles; pressure P0 varied from 0.17 to 0.58 MPa.
Exposure 2: Temporal interference tFUS, 1 + 0.8 MHz, without microbubbles
Target: primary motor cortex — “right M1 region / mouse motor cortex”
Device: not reported
| Waveform | pulsed, other_patterned | |
|---|---|---|
| Fundamental frequency (kHz) | 1,000, 800swept | ✓✓✓⚑ |
| 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) | 0.4 | ✓✓✓ |
| 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) | 330, 580swept | ✓✓✓ |
| In-situ Isppa (W/cm²) | not reported | |
| In-situ Ispta (W/cm²) | not reported |
Two-frequency temporal interference (1 + 0.8 MHz) with the same 400 ms stimulation, 3.6 s interval, 1000 Hz PRF and 40 % DC; with and without microbubbles.
Flags from extraction
exposures[0].unspecified_domain.pressure_kpa— Peak pressures 0.17, 0.25, 0.33, 0.58 MPa are described as measured at the focus posterior to the skull while the field was characterised in degassed water; domain unclear. The quote contains only 0.33 and 0.58.exposures[0].timing.duty_cycle_pct— 40 % DC is stated in the Results, not in the Methods parameter list; pulse duration not stated, left not_reported.exposures[1].fundamental_frequency_khz— TI combines 1 and 0.8 MHz (0.81 MHz in the simulation table); recorded as a list.n_subjects— Number of mice is not stated in the text.exposures[0].label— Microbubbles were injected in some arms; under INCLUSION.md E4 (any arm given with microbubbles) this paper may be out of scope.exposures[0].device.family— Transducer maker not named; only a 1 MHz focused transducer with 20 mm aperture is described.