When researchers at Oregon Health & Science University wanted to study one of the ways that alcohol affects the brain, they turned to zebra finches -- and got them drunk.
"Speech impairment is one of the most intriguing and least understood effects of alcohol on cognitive function, largely due to the lack of data on alcohol effects on vocalizations in the context of an appropriate experimental model organism," the researchers wrote in their study, published this month in the journal PLOS One.
Zebra finches can serve as a model for humans because the neural structure that underlies their vocalizations is very well understood and easy for scientists to study, and because the way they learn song is analogous to the way people learn speech.
To make sure that they could be used to study the effects of alcohol on the human brain, the Oregon team had to make sure of three things: that birds will drink alcohol, that they'll get drunk, and that being drunk affects their songs.
They will. They do. It does.
The birds readily drank alcohol when presented with spiked juice, and drinking it raised their blood ethanol concentrations significantly. On average, the birds had a blood alcohol level of 0.04. (One bird, if pulled over, would have blown a 0.08, enough to earn him a DUI.) They didn't get sleepy or lose their ability to fly normally, but the booze did change the way they sang.
Though not immediately recognizable to the human ear, as demonstrated in the recording above, there were differences in two acoustic variables. Amplitude, a measurement of loudness, decreased in drunk birds, while entropy, which relates to the organization of a sound, went up. That means the birdsong went from being a clear tone to sounding more like white noise, Christopher Olson, Ph.D., one of the authors, explained.
The slurred syllables became more obvious when the recordings were slowed down to half-speed.
The researchers hope to use their findings to perform further experiments that will help elucidate what happens on a neural level when people drink, and how that affects vocal control.
"This study on the effect of alcohol on song production was necessary to lay the ground work to use the finch model to understand how alcohol works in the brain," said Olson. "Because of this result we now have a compelling reason to believe that alcohol does affect the underlying neurological circuitry, and ... we are now able to test some very specific and important ideas about how alcohol may affect brain function and vocal development more generally, and importantly how that alters vocal learning and production in humans."
It may even be possible one day, the scientists posit, to use acoustic analysis as a test of intoxication.
Just imagine a karaoke machine that confiscates your keys after one too many drunken renditions of "Don't Stop Believin'."