Sending ultrasound waves to specific areas of the brain may elevate a person's mood, causing them to feel lighter and happier, a new study has found.
The finding potentially could lead to new treatments for psychological and psychiatric disorders.
Dr Stuart Hameroff and colleagues from the University of Arizona applied transcranial ultrasound to 31 chronic pain patients in a double blind study in which neither doctor nor subject knew if the ultrasound machine had been switched on or off.
Patients reported improvements in mood for up to 40 minutes following treatment with brain ultrasound, compared with no difference in mood when the machine was switched off.
The researchers confirmed the patients' subjective reports of increases in positive mood with a Visual Analog Mood Scale, or VAMS, a standardised objective mood scale often used in psychological studies.
"Because important structures called micro-tubules in all brain neurons vibrate in the ultrasound range, and help mediate mood and consciousness, transcranial ultrasound TUS may benefit a variety of neurological and psychiatric disorders," Hameroff said.
The discovery may open the door to a possible range of new applications of ultrasound in medicine.
"We frequently use ultrasound in the operating room for imaging. It's safe as long as you avoid excessive exposure and heating," said Hameroff.
Jay Sanguinetti, a doctoral candidate in the department of psychology and his adviser John Allen, professor of psychology, were intrigued by Hameroff's idea of testing ultrasound.
They conducted a follow-up study of ultrasound on UA psychology student volunteers, recording vital signs such as heart rate and breath rate, and narrowed down the optimum treatment to 2 megahertz for 30 seconds as the most likely to produce a positive mood change in patients.
"With 2 megahertz those who were stimulated with ultrasound reported feeling 'lighter,' or 'happier;' a little more attentive, a little more focused and a general increase in well-being," Sanguinetti said.
The study was published in the journal Brain Stimulation.