Intramembrane cavitation (NICE model)

A leading candidate mechanism for how ultrasound modulates neurons without heating them appreciably: the bilayer sonophore hypothesis, formalised as the Neuronal Intramembrane Cavitation Excitation (NICE) model, proposes that the acoustic pressure wave periodically expands and contracts nanoscale gas pockets between the two leaflets of the lipid membrane, mechanically deforming it and changing its capacitance enough to generate displacement currents that can drive spiking.

NICE is a physically motivated, quantitatively predictive model, but it is one of several competing accounts — mechanosensitive ion channels (Piezo1, TRP, and two-pore-domain potassium channels such as TREK-1 and TREK-2), direct thermal effects, and acoustic radiation force all have experimental support. The mechanism is almost certainly parameter- and cell-type-dependent, and no single model yet explains all observations.