The impact of transcranial ultrasound on auditory brainstem responses and neuronal activation in the cochlear nucleus
Shang-Yi Hsueh, Ying-Chang Lu, Jormay Lim, Ya-Cherng Chu, Pei-Hsuan Lin, Yen-Hui Chan, Yu-Wei Wu, Chen-Chi Wu, Jaw-Lin Wang
Hearing Research 2025, 466, 109379 · 10.1016/j.heares.2025.109379
Abstract
Objectives Transcranial ultrasound stimulation (TUS) is a non-invasive technique with therapeutic potential for neurodegenerative diseases. Given its increasing therapeutic relevance, it is essential to identify any unintended consequences, especially on vulnerable systems such as the auditory pathway. Specifically, the precise impact of TUS on auditory responses and neural activation patterns within the central auditory system remains unclear. We hypothesized that TUS could indirectly modulate central auditory processing, even at frequencies outside the direct hearing range, leading to observable changes in auditory brainstem responses (ABRs) and neuronal activity in the cochlear nucleus. Design We analyzed periodic ABR recordings before and after 1 MHz ultrasound stimulation in mice. To investigate the immediate and long-term engram effects of ultrasound stimulation in the cochlear nucleus, we used c-Fos TRAP2 mice. All mice received a 12 kHz pure tone stimulation to establish the tonal signature in the cochlear nucleus. We administered ultrasound stimulation transcranially over the entire brain, covering the region including the cochlear nucleus, either immediately prior to the first tone presentation (ultrasound preconditioning group) or 30 minutes prior to sacrifice (acute ultrasound group) to analyze the long-term and immediate responses to ultrasound stimulation, respectively. A sham control group received only the 12 kHz tone stimulation. Results Ultrasound stimulation induced latency shifts in ABR recordings. The effect of ultrasound on latency was more pronounced at regions of the auditory pathway farther from the inner ear. A significant increase in immediate neural activation was observed in the acute ultrasound group, while a trend toward an increase in long-term engram effect was seen in the ultrasound preconditioning group. A broader band pattern of neural activation was consistently identified in the cochlear nucleus following TUS. These results suggest that TUS can affect neural activation in the cochlear nucleus, manifesting as ABR latency shifts. Conclusions This study provides evidence that ultrasound stimulation can induce latency shifts in ABR recordings and alter neuronal activation patterns in the cochlear nucleus, indicating a modulatory effect of ultrasound on the auditory pathway. The observed activation of neurons along the auditory pathway by ultrasound may offer therapeutic opportunities to improve auditory transduction in patients with central auditory pathway dysfunction, such as auditory neuropathy.
Abstract via europepmc.
Exposures
Exposure 1: Transcranial ultrasound stimulation covering the entire brain (including the cochlear nucleus)
Target: whole brain or unfocused — “entire brain, including the cochlear nucleus”
Device: Olympus / Panametrics · Olympus · C539-SM ✓
| Waveform | pulsed | |
|---|---|---|
| Fundamental frequency (kHz) | 1,000 | ✓✓✓ |
| Pulse duration (ms) | not reportedimplied by duty cycle ÷ PRF: 0.01 ms (not stated by the paper) | ⚑ |
| Pulse repetition frequency (Hz) | 1,000 | ✓✓✓ |
| Duty cycle (%) | 1 | ✓✓✓ |
| Sonication duration (s) | 60 | ✓✓✓ |
| 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) | 50 | ✓✓✓ |
| Ispta, domain unspecified (W/cm²) | 0.043 | ✓✓✓ |
A commercially available 1-MHz ultrasound transducer was placed on the shaved head of the mouse in an anterior-posterior position between the eyes and ears to ensure coverage of the entire brain, including the cochlear nucleus. TUS was applied for 1 min, either between the 5th and 6th ABR recordings, immediately prior to the first 12 kHz tone presentation (ultrasound preconditioning group), or 30 minutes before sacrifice / immediately prior to the second tone presentation (acute ultrasound group).
Flags from extraction
n_subjects— Paper never states a single total of ultrasound-exposed animals; list combines the ultrasound preconditioning (n=6) and acute ultrasound (n=5) groups from the cochlear-nucleus mapping cohort (quoted) plus the separate ABR ultrasound (US) group (n=4, stated in a different sentence: '8 wild-type mice were used, split into an ultrasound (US) group (n = 4) and a control group (n = 4)').randomised— Random assignment is stated only for the cochlear-nucleus mapping cohort (sham/preconditioning/acute groups); not stated for the ABR US/control groups.sham_type— Neither the ABR control group nor the cochlear-nucleus sham/tone-only groups are described with a specific sham mechanism (e.g., inactive transducer); classified as other.exposures[0].timing.pulse_duration_ms— Duty cycle (1%) and PRF (1 kHz) are stated but the paper does not itself state a pulse duration; left not_reported rather than computed.