Leonid R. Gavrilov
Lab. of Med. Acoust., N. N. Andreev Acoust. Inst., Moscow V-36, 117036, Russia
It has been shown that short and relatively intense pulses of focused ultrasound (FUS) are able to stimulate selectively a variety of nervous structures [L. R. Gavrilov, Ultrasonics 22, 132--138 (1984)]. Different tactile, temperature (warmth and cold), and various pain sensations can be produced in the skin at the surface of the body. Pain sensations can also be produced in deep-seated structures, e.g., joints and muscles. Pulsed FUS acting on electroreceptors of skates induced spikes of neuronal activity. Stimulation of the ear labyrinth in humans with normal hearing by amplitude-modulated FUS induced hearing sensations that corresponded to the envelope of the amplitude-modulated ultrasonic signal. In similar circumstances deaf people, with clinically diagnosed destruction of the hair cells in the labyrinth, perceived the FUS signals. The mechanism of all these physiological phenomena has been attributed primarily to a mechanical effect of the FUS stimulation of the nerve structures. FUS stimulation has been applied successfully to the clinical diagnosis of a number of neurological and dermatological diseases and hearing disorders involving changes in the perception of various sensations.