"Dance for PD" classes use music to temporarily ease tremors and get Parkinson's patients moving.
"Dance for PD" classes use music to temporarily ease tremors and get Parkinson's patients moving. Maggie Starbard/NPR
Even if you can't keep a beat, your brain can. "The brain absolutely has rhythm," says Nathan Urban, a neuroscientist at Carnegie Mellon University in Pittsburgh.
you concentrate, Urban says, your brain produces rapid, rhythmic
electrical impulses called gamma waves. When you relax, it generates
much slower alpha waves.
The internal cadences of the brain and nervous system appear to
play an important role in everything from walking to thinking, Urban
says. And abnormal rhythms, he says, have been associated with problems
including schizophrenia, epilepsy, autism and Parkinson's disease.
rhythms of the brain begin with the firing patterns of individual brain
cells. Some types of cells tend to fire as slowly as once a second,
while others tend to fire more than a hundred times as fast. "They're
little clocks," Urban says. "They have an intrinsic frequency."
All those different beats in the brain could produce chaos. One
reason they don't is that groups of brain cells synchronize when they
need to get something done. So, when a mouse is exploring a new place,
cells begin firing together in areas of the brain involved in navigation
Urban has been studying how brain cells achieve this synchrony and
has found evidence that it works a bit like a room full of people
clapping their hands. At first, each person claps to his own beat. But
if you ask them to clap together, they'll start listening to their
neighbors and adjusting their rhythms until the claps are synchronized.
cells appear to do something very similar, Urban says. There's still
debate about why this synchronization takes place. But many scientists
believe it's important, because they know that when any two cells fire
together, the connections between them get stronger, a process that is
critical to learning and memory.
The Rhythms of Digestion and Dance
course, rhythms in the brain and nervous system also control many
rhythms in the body. Among these rhythms are the repetitive muscle
contractions responsible for functions as basic as digestion and as
elevated as dance, says Eve Marder,
a biology professor at Brandeis University. Marder has spent years
studying the complex patterns of nerve cell firing that allow crabs to
chew, filter and digest their food.
"It turns out that the stomach of a crab is a very, very complicated mechanical device,"
driven by the precisely choreographed contractions of 42 sets of
muscles, Marder says. And the way a crab processes lunch has a lot in
common with the way a ballerina does pliés, she says. Both actions rely
on circuits of nerve cells that fire in a sequence, activating one
muscle, then another, then another until the pattern repeats.
Rhythmic sequences are also required to move around, says Mark Churchland,
a brain scientist at Columbia University. Walking, for example,
requires repeatedly lifting a foot up, putting it down, and pushing it
back. Fish swish a tail from side to side to swim. "It's sort of hard to
imagine any way of doing continuous locomotion that wasn't built on a
rhythmic underpinning," Churchland says.
Many of these rhythms
are maintained by cells in the nervous system, not the brain, Churchland
says. This means the brain can use a kind of shorthand to control
motion. So instead of sending instructions for each muscle contraction
needed to take a step, the brain sends a general command: "Activate the
What's interesting, Churchland says, is that
the brain may be using this rhythmic shorthand for some motions that
don't appear rhythmic at all, like reaching. "You start with your hand
in one place and you move your hand to another place. There's nothing
rhythmic about that," he says.
But when Churchland took a closer look at reaching he found something really surprising. "That pattern of muscle activity is the sum of two rhythms," he says.
When Rhythms Go Wrong
teacher Lucy Bowen McCauley (second from left) finds that simply
humming can help her students with Parkinson's get their feet to
"unfreeze" and match the song's rhythm.
Diseases including epilepsy, schizophrenia and Parkinson's can
disrupt the brain's normal rhythms. People with Parkinson's disease, for
example, tend to develop abnormal firing patterns in their brains that
result in tremor and other difficulties with movement.
these symptoms of Parkinson's are greatly reduced when patients respond
to the external rhythms of music and dance. This transformation is easy
to see at a studio in Silver Spring, Md., where Lucy Bowen McCauley teaches a dance class designed for people with Parkinson's.
Anne Davis (left) and Phyllis Richman get in sync with each other
during a mirror game in their dance class in Silver Spring, Md.
When a half dozen of her students arrive for class, their steps
are halting, their gestures visibly distorted by tremors. After some
warm-up exercises, they make their way to folding chairs on the dance
floor and sit. Then, as the sound of Ella Fitzgerald fills the room and
McCauley calls out "heel, heel, heel, toe, toe, toe," the group begins
tapping out the beat in unison.
"When we use music, these Parkinson's patients become dancers," McCauley says. "They look graceful and they can move in rhythm."
class, some students talk about the role that rhythm plays in their
disease. "My doctor says he can tell a Parkinson's tremor from any other
kind," says Anne Davis, a retired teacher who's had the disease for
more than 15 years. That's because the tremors of Parkinson's have their
own distinctive rhythm, Davis says.
And a man-made rhythm has helped reduce her tremor, she says. It comes from an implanted deep brain stimulation device
that sends high-frequency electrical impulses to the area causing her
hands to tremble. Scientists think the fast pulses somehow override the
much slower rhythm responsible for tremor.
patients also experience something called freezing — a temporary
inability to initiate a movement like taking a step. "You're trying to
go forward or sideways or whatever and your feet won't move," says
Phyllis Richman, another student in the dance class and a former food
critic for the Washington Post. "So then you fall," Davis adds.
But musical rhythms have a remarkable ability to help Parkinson's patients unfreeze,
McCauley says. "Two times I've had people really have trouble walking
down the hall to get to the class," she says. The solution: "We hum a
tune. One time I did a march and one time I did a waltz. And we got in
sync with the rhythm and they were able to get their feet to match."
course, dance doesn't halt the brain damage caused by Parkinson's. But
McCauley's students say the rhythms of dance give them a respite from
the abnormal brain rhythms of Parkinson's. "I come here because this is
where I get joy," Davis says.