The hippies were right -- listening to music while taking LSD really does open your mind.
Scientists at the University of Auckland and in Europe have been conducting a number of studies into the effects of LSD on the brain. Earlier this week they reported on how it could can created "profound, sometimes life-changing experiences in microgram doses", potentially opening up uses in psychological treatment.
Now they've described how people tripping on acid experience music.
Volunteers were given 75mcg doses of LSD, asked to lie down in an MRI machine and listen to ambient music (in particular the album Yearning, by Lisa Moskow and Robert Rich).
Compared to control tests where they didn't listen to anything at all, or weren't tripping, the subjects reported seeing "enhanced eyes-closed visual imagery, including imagery of an autobiographical nature".
The scans showed this came about thanks to a "much higher information flow than normal between the brain region involved in musical emotion and the part involved in vision".
"These results extend our understanding of circuitry involved in visual imagery and suggest how LSD and music can work in synergy to enhance this phenomenon," the authors conclude in the study, published in journal European Neuropsychopharmacology.
"The present results provide the beginnings of a mechanistic explanation for the role of music listening in psychedelic drug-assisted psychotherapy; however, a large amount of work is required to develop our understanding of whether and how psychedelic-assisted psychotherapy can be effective."
The popularity of LSD in counter-culture circles coincided with the acid-rock movement, with bands like the Beatles, the Grateful Dead and Pink Floyd writing music that appealed to users.
The authors say further studies are needed to see how different types of music might affect different people, if LSD-assisted musical therapy is to become a useful tool.