It is a well known fact that whales, bats, and even praying mantises use ultrasound as a sensory guidance system, and now a new study has found that ultrasound can modulate brain activity to heighten sensory perception in humans.
Scientists at Virginia Tech Carilion Research Institute have demonstrated that ultrasound directed to a specific region of the brain can boost performance in sensory discrimination.
The study provides the first demonstration that low-intensity, transcranial-focused ultrasound can modulate human brain activity to enhance perception.
The scientists delivered focused ultrasound to an area of the cerebral cortex that processes sensory information received from the hand. To stimulate the median nerve - a major nerve that runs down the arm and the only one that passes through the carpal tunnel - they placed a small electrode on the wrist of human volunteers and recorded their brain responses using electroencephalography, or EEG.
Then, just before stimulating the nerve, they began delivering ultrasound to the targeted brain region.
The scientists found that the ultrasound both decreased the EEG signal and weakened the brain waves responsible for encoding tactile stimulation.
They also found that the subjects receiving ultrasound showed significant improvements in their ability to distinguish pins at closer distances and to discriminate small frequency differences between successive air puffs.
"It seems paradoxical, but we suspect that the particular ultrasound waveform we used in the study alters the balance of synaptic inhibition and excitation between neighboring neurons within the cerebral cortex," lead author William "Jamie" Tyler said.
"We believe focused ultrasound changed the balance of ongoing excitation and inhibition processing sensory stimuli in the brain region targeted and that this shift prevented the spatial spread of excitation in response to stimuli resulting in a functional improvement in perception," the researcher said.
The study is published in journal Nature Neuroscience.
