Ultrasound has a long history of use as a diagnostic tool in medicine, however in the last few years it is gaining increased attention as an alternative to more traditional techniques for manipulating and stimulating nerve cells. Because of its physical properties it is effective in penetrating tissue and delivering energy to a specific location through thermal (heating up tissue) and nonthermal mechanisms (main one being cavitation). The most commonly used neuromodulation techniques nowadays are invasive, cannot penetrate deep into tissue and/or have bad spatial resolution. US can penetrate the skull in a focused manner and excite or inhibit action potentials, which could enable the development of a noninvasive therapy for patients with psychiatric diseases that do not respond well to more traditional forms of treatment. Furthermore US is suitable for manipulating cells with regulatory molecules that respond to thermal and nonthermal stimulus from a distance. US effects are enhanced by a larger intensity of US, longer duration of the stimulus and with the delivery of contrast agents near the targeted location. There are many hypothesis concerning the underlying mechanisms of US stimulation of AP. The main idea is that the mechanical stimulus directly or indirectly effects ion channels and thus the change in membrane potential.
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