Frequency and Timing‐Dependent Effects of Ultrasound on Neural Responses: Comparative Analysis With Whisker Stimulation in Rats
Ye Yuan, Tian Liu, Jue Wang
Journal of Neuroscience Research 2025, 103 · 10.1002/jnr.70100
Abstract
This study explores whether ultrasound can induce short-term synaptic plasticity (STP)-like effects at the systems level by modulating cortical excitability and sensory responsiveness. We designed a temporally shifted sensory paradigm to test how ultrasound frequency (1, 2, and 4 MHz), inter-stimulus interval (10, 25, and 100 ms), and stimulation order (ultrasound-whisker vs. whisker-ultrasound) affect cortical responses in the rat barrel cortex. Thirty Sprague-Dawley rats underwent an identical experimental protocol. Electrocorticography (ECoG) signals were recorded from the C2 barrel column, and neural responses were assessed by peak amplitude, latency, and power spectral density. Whisker stimulation alone evoked strong cortical responses, significantly greater than ultrasound stimulation. Notably, when ultrasound preceded whisker stimulation by 25 ms, subsequent whisker responses were significantly enhanced, suggesting the existence of a cortical "excitability window" for neuromodulation. This facilitation effect was absent with time intervals of 10 and 100 ms. Mechanistically, ultrasound may modulate membrane tension and activate mechanosensitive ion channels to transiently lower the activation threshold of cortical neurons. These findings reveal that ultrasound can temporally enhance cortical excitability and sensory responsiveness in a frequency- and timing-dependent manner. Our results provide systems-level evidence of STP-like neuromodulation and provide the potential of ultrasound as a noninvasive method for dynamic control of sensory processing.
Abstract via europepmc.
Exposures
Exposure 1: Ultrasound stimulation of C2 barrel column (frequency and whisker-timing paradigm)
Target: primary somatosensory cortex — “C2 barrel column, primary somatosensory cortex (S1BF)”
Device: other named manufacturer · Siansonic Inc. ✓
| Waveform | pulsed | |
|---|---|---|
| Fundamental frequency (kHz) | 1,000, 2,000, 4,000swept | ✓✓✓ |
| Pulse duration (ms) | 0.1 | ✓✓✓ |
| Pulse repetition frequency (Hz) | 500 | ✓✓✓ |
| Duty cycle (%) | not reportedpulse duration × PRF gives 5% | ⚑ |
| Sonication duration (s) | 2 | ✓✓✓ |
| 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 | |
| Ispta, domain unspecified (W/cm²) | 0.7 | ✓✓✓⚑ |
A craniotomy was performed and the skull removed so that ultrasound was delivered directly onto the exposed dura via coupling gel. Three ultrasound frequencies (1, 2, 4 MHz) were tested in each animal with intensity and PRF held constant. Ultrasound was combined with whisker stimulation in whisker-ultrasound (W-U) and ultrasound-whisker (U-W) sequences at inter-stimulus intervals of 10, 25, and 100 ms. Each stimulation session lasted 2 s, with 100 continuous stimulations per condition, a 3-min inter-sequence interval, and a 1-h rest between different ultrasound frequencies in the same animal.
Flags from extraction
n_sessions_per_subject— Each animal underwent a single terminal craniotomy experiment covering all frequency/interval conditions, but the paper does not explicitly state a number of sessions per animal.exposures[0].timing.duty_cycle_pct— Duty cycle not explicitly stated; only PRF (500 Hz) and pulse duration (100 µs) are given, which would allow computation (5%) but this was not done per the no-arithmetic rule.exposures[0].unspecified_domain.ispta_w_cm2— Domain of the reported Ispta (700 mW/cm2) is not stated as free-field or in-situ; ultrasound is applied directly onto the exposed dura (craniotomy) via gel, with no skull path, but the paper does not label the measurement domain.sham_type— No sham/placebo ultrasound condition was used; whisker-only and ultrasound-only conditions served as unimodal reference comparators, not an inactive-device sham.