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The Neurobiology of Rhythm

(Brief Notice: I am not going to go through the "bootstrap" discussion again. Suffice it to say I am over most of the wretched emotions that have kept me from posting, and I am planning to resume regular posting.)

I am not sure if this video clip has reached your neck of the woods yet, but it has made an impact at many universities because it is relevant to a key question in neurobiology. Namely, the study published in Science News on April 30th, shows that birds (namely parrots) have the ability to discern and follow rhythms. This seemingly "silly" finding is actually monumental in neuroscience and helps us see that PERCEPTION of rhythm is not only a human attribute.

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Birds Bust a Move to Musical Beats: Parrots Display a Flair for Moving in Time to Music, a Skill Usually Attributed Only to People

By Bruce Bower

New research shows that Snowball the sulfur-crested cockatoo moves in time to musical beats, an ability long attributed only to people.

Don’t begrudge Snowball his hankering for boy bands. The sulfur-crested cockatoo with a spiky haircut bobs his head, sways his body and stomps his feet in time to the beat of pop songs such as the Backstreet Boys’ “Everybody.”

Two new studies, published online April 30 and slated to appear in Current Biology, indicate that he and members of many other parrot species can synchronize head bobs and other rhythmic movements to musical beats. Until now, most researchers thought that only people align physical movements to timed sounds, a phenomenon known as entrainment.

“This is the first evidence that there could be an animal model of rhythm perception in music,” says neuroscientist Aniruddh Patel of The Neurosciences Institute in San Diego. Patel directed one of the new investigations.

In 2006, Patel proposed that brain circuitry for vocal learning gets co-opted to support musical-beat perception and synchronized movements to music. This would explain why humans and parrots can imitate sounds and move in time to a beat. But animals that can’t imitate sounds, including chimpanzees, monkeys, dogs and cats, can’t keep the beat. If Patel’s right, then other vocal mimics — including songbirds, dolphins, elephants, walruses and seals — should be able to get their groove on.

Music’s origins remain a mystery. Some researchers regard music as a pleasurable by-product of other mental skills, such as language. Others suspect music arose as an evolutionary adaptation to Stone Age life, perhaps to promote social cohesion. Whatever the case, even newborns recognize rhythmic sequences (SN: 2/14/09, p. 14).

“Even if entrainment emerged as a by-product of vocal mimicry, other parts of music perception and cognition may easily be adaptive,” says Harvard University’s Adena Schachner, a psychology graduate student who directed the other new study.

Evidence of what amounts to a kind of dancing to music by at least some parrot species “comes as a big surprise,” remarks psychologist W. Tecumseh Fitch of the University of St. Andrews in Fife, Scotland. “Scientists have claimed that this capacity is uniquely human for several decades.”

Fitch says the parrots can serve as an animal model to probe brain mechanisms involved in synchronizing movements to musical beats. The new findings also underscore the need to examine how parrots use vocal mimicry and, possibly, entrainment in the wild, Fitch says.

The fact that Snowball and other bopping birds exhibit entrainment without making music themselves supports the idea that “the ability to entrain is a side effect of brain mechanisms that evolved to support other functions in humans,” comments neuroscientist Josh McDermott of New York University.

But parrots won’t provide an animal model of entrainment if further work shows that they perceive sound rhythms using different brain mechanisms than people, McDermott adds. Such a finding would suggest entrainment evolved at least twice. It’s also unclear to what extent training or encouragement by others affects the ability of either parrots or people to move in time to music, he notes.

Patel’s team studied Snowball after seeing a YouTube video of the cockatoo’s deftly synchronized moves to a pop song. Now 12 years old, Snowball was given to a bird-rescue facility almost two years ago by his owners.

In experiments Patel and his team conducted at the bird-rescue service, Snowball perched on the back of an armchair and listened to his favorite dancing tune, the Backstreet Boys’ “Everybody.” The music sped up or slowed down across a range of tempos on different trials.

Snowball frequently adjusted the tempo of his dancing to stay synchronized to the beat, Patel says. Bouts of synchronized movement were interspersed with periods during which Snowball danced more slowly or quickly than the beat. Experiments conducted by other researchers have found a similar pattern of intermittent entrainment among dancing preschool children.

Schachner’s group played familiar and unfamiliar musical pieces to Snowball, to an African gray parrot named Alex and to eight human volunteers. Alex was studied before his death in September 2007.

When listening to the same music, the birds synchronized their movements to the beat about as accurately as volunteers tapped a button to the beat.

The researchers then analyzed thousands of YouTube videos showing several hundred animal species moving to music. Signs of entrainment to a beat appeared only in vocal mimics, represented by 14 parrot species and Asian elephants that moved their trunks or legs in time with music.

Patel suspects that, as with people, some parrots have rhythm to spare and others can’t pick up a beat with a forklift. Snowball’s dancing, it seems, has more in common with boy band *NSYNC.

Snowball, a sulfur-crested cockatoo, bobs his head, sways his body and stomps his feet to a percussive musical tune. Experiments indicate that Snowball is able to synchronize his movements to a musical beat, challenging the longstanding belief that only people can dance in this way.

Alex the African gray parrot takes a cool, head-bobbing approach to moving with the music, whereas Snowball fiercely stomps out the beat to Queen’s "Another One Bites The Dust."

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A very interesting article, indeed. It has gotten my own creative juices about research going.

PipeTobacco