Modulation of the functional state of the brain with the aid of focused ultrasonic action.

We investigated the possibility of modifying the functional state of the brain with the aid of focused ultrasound and studied various regimes of its action. A specific pattern in the effect of focused ultrasonic action was discovered with regard to its intensity: the effect is absent at low (less than 0.1 mW/cm2) intensities; activation of bioelectrical activity in the brain takes place at intensities from 1 to 100 mW/cm2; and suppression of the ECoG takes place at intensities from 1 to 100 W/cm2. On the basis of our own data and the data in the literature, we suggest that the mechanism of ultrasound action is based upon changes in the permeability of neuronal membranes leading, after a chain of intracellular molecular reactions, to a subsequent general de- or hyperpolarization of the membranes of neuronal populations and to a change in the bioelectrical activity of the brain.