To understand how low-frequency ultrasound (LILFU) stimulates brain circuit activity, you have to grasp what's going on with your gray matter when doctors aren't using high-tech gadgetry to blast it with sound waves.
Brain cells release neurotransmitters, molecules that carry information from one nerve cell to another across small gaps called synapses. When they arrive at another cell, neurotransmitters cause ion channels to open, which in turn triggers the electrical impulses that pass messages along nerve fibers. These reactions are a vital component of the brain's circuitry, and neurotransmitter disruptions are symptoms of such debilitating conditions as Alzheimer's disease, Parkinson's disease, depression and epilepsy.
The team of neuroscientists at Arizona State University found that LILFU waves boosted the release of neurotransmitters, possibly by opening up sodium and calcium ion channels enough to trigger action potentials, which in turn release neurotransmitters. This means that, without invasive surgery, physicians in the future may be able to undo the damage produced by diseases such as Alzheimer's by stimulating the production of the very neurotransmitters that the condition disrupts.
It will take years of research and development before LILFU technology is ready to alter human brain circuitry and nonsurgically repair neurological injuries and diseases.
As you might imagine, however, the effects of ultrasound on the human brain haven't inspired only therapeutic innovations. Various studies have reportedly theorized that ultrasonic weapons could be used to induce vomiting and nausea in victims -- perhaps during a riot-control scenario [source: Jauchem]. Other scientists suggest that the technology could eventually allow us to manipulate human memory.
Ultrasonic mind control is a science very much in its infancy. With enough research, we might one day live in an age where police use ultrasound to incapacitate you at a protest, while physicians optimize human brain efficiency with a little ultrasonic fine-tuning.
Explore the links on the next page to learn even more about ultrasound and the human brain.