How focused ultrasound changes neural activity
In plain words
Low-intensity sound aimed at the brain changes how neurons fire, and the reason is disputed. Part of the measured effect may come from the subject simply hearing the pulse.
Precise statement
Identify the mechanism by which focused ultrasound at $0.2\ \text{to}\ 1.5\ \mathrm{MHz}$, spatial-peak pulse-average intensity below about $10^8\ \mathrm{erg}/(\mathrm{s}\ \mathrm{cm}^{2})$ and mechanical index below 1, modulates neuronal firing. Candidates: radiation force and membrane strain, intramembrane cavitation, mechanosensitive ion channel activation, local heating of order $0.1\ \mathrm{K}$, and indirect auditory activation. An answer is a mechanism predicting the sign and magnitude of the effect versus frequency, pulse length and duty cycle.
What would settle it
Experiments with auditory confound removed, varying frequency and pulse parameters independently, with simultaneous measurement of displacement, temperature and neural response.
Status in the literature
Unverified note
Auditory confounding demonstrated in rodents in 2018 forced reinterpretation of earlier results; no consensus mechanism as of 2025.