Low-Frequency Amplitude-Modulated Ultrasound Stimulation Drives Hippocampal Oscillations and Enhances Memory in Mice
Ruru Wang, Xu Liu, Xin Wang, Xiaoqing Zhou, Jingna Jin, He Wang, Zhipeng Liu, Ren Ma, Tao Yin
IEEE Transactions on Neural Systems and Rehabilitation Engineering 2026 · 10.1109/tnsre.2026.3664390
Abstract
Although transcranial ultrasound stimulation (TUS) can noninvasively target the hippocampal oscillatory network, which serves as a critical interface between cellular functions and cognition, its modulatory efficiency is constrained by the low-pass filtering properties of neuronal membranes. To overcome this limitation, we developed a low-frequency amplitude-modulated (AM) TUS paradigm to enhance neuromodulatory efficiency by improving resonance within the hippocampal oscillatory network. We applied 5, 40, and 80 Hz sinusoidal AM-TUS and 5 Hz pulsed AM-TUS to the mouse hippocampus, and analyzed local field potentials before and after stimulation. Results showed that 5 Hz sinusoidal AM-TUS significantly enhanced the phase locked value (PLV) (increment: $0.054\pm 0.017$ ) and coherence (increment: $0.040\pm 0.016$ ) in the theta band, and the phase-amplitude coupling (PAC) in theta-low gamma (increment, $1.521\pm 0.249$ ) and theta-high gamma (increment, $0.821\pm 0.299$ ) bands. In contrast, the 5 Hz pulsed AM-TUS showed negligible effects. While the 40 Hz sinusoidal AM-TUS enhanced PLV and coherence in the theta band and PAC in theta-low gamma bands, the 80 Hz sinusoidal AM-TUS only enhanced PLV in the theta band. Thus, the 5 Hz sinusoidal AM-TUS demonstrated superior neuromodulatory efficiency over all other paradigms. The outstanding modulatory efficiency of 5 Hz sinusoidal AM-TUS on the oscillatory network was further confirmed in the 14-day TUS, demonstrating enhancements in spatial learning and memory. The 5 Hz sinusoidal AM-TUS presents a novel and efficient approach to precisely modulating hippocampal oscillatory network through entrainment.
Abstract via europepmc.
Exposures
Exposure 1: Sinusoidal and pulsed AM-TUS, hippocampus
Target: hippocampus — “mouse hippocampus”
Device: other named manufacturer · Institute of Acoustics, Chinese Academy of Sciences · 0.5M-D20-F20 ✓
| Waveform | other patterned | |
|---|---|---|
| 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) | 1 | ✓✓✓ |
| 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) | not reported | |
| In-situ Ispta (W/cm²) | not reported | |
| Pressure, domain unspecified (kPa) | 380 | ✓✓✓ |
| Ispta, domain unspecified (W/cm²) | 0.3 | ✓✓✓⚑ |
Base sequence of 500 kHz carrier, 1 kHz PRF and 40% duty cycle, amplitude-modulated by a low-frequency sine (envelope 5, 40 or 80 Hz) or gated by a 5 Hz square wave with 64% duty cycle (pulsed AM-TUS). 150 sessions each with 1 s duration and 3 s interval (about 10 min per hemisphere daily for 14 days in the behavioural cohort); 5 Hz, 40 Hz and 80 Hz envelope protocols separated by 7-day washouts in the electrophysiology cohort.
Flags from extraction
n_subjects— Two separate cohorts of 24 mice each (electrophysiology and behaviour); sham mice are included in the 48.n_sessions_per_subject— 14 days applies to the behavioural cohort; the electrophysiology cohort received single sessions per protocol (5, 40, 80 Hz) separated by 7-day washouts.exposures[0].timing.pulse_duration_ms— Pulse duration not stated; only 1 kHz PRF and 40% duty cycle of the base sequence are given.exposures[0].timing.duty_cycle_pct— 40% is the base-sequence duty cycle before low-frequency amplitude modulation; pulsed AM-TUS adds a further 64% gating.exposures[0].unspecified_domain.ispta_w_cm2— Intensity and pressure are given without stating water or in situ; Ispta 300 mW/cm2 recorded as 0.3 W/cm2. Pressure is stated for sinusoidal AM-TUS.exposures[0].timing.waveform— Amplitude-modulated carrier, so other_patterned.exposures[0].fundamental_frequency_khz— Envelope frequencies 5, 40 and 80 Hz are listed in the protocol description, not as exposures.