Since his birth 33 years ago, Jonathan Keleher has been
living without a cerebellum, a structure that usually contains about half the
brain's neurons.
This exceedingly rare condition has left Jonathan with a
distinctive way of speaking and a walk that is slightly awkward. He also lacks
the balance to ride a bicycle.
But all that hasn't kept him from living on his own, holding
down an office job and charming pretty much every person he meets.
"I've always been more into people than anything
else," Jonathan tells me when I meet him at his parents' house in Concord,
Mass., a suburb of Boston. "Why read a book or why do anything when you
can be social and talk to people?"
Jonathan is also making an important contribution to
neuroscience. By allowing scientists to study him and his brain, he is helping
to change some long-held misconceptions about what the cerebellum does. And
that, in turn, could help the hundreds of thousands of people whose cerebellums
have been damaged by a stroke, infection or disease.
For decades, the cerebellum has been the "Rodney
Dangerfield of the brain," says Dr. Jeremy Schmahmann, a professor of
neurology at Harvard and Massachusetts General Hospital. It gets no respect because
most scientists only know about its role in balance and fine motor control.
You can learn a lot about that role by watching someone
who's been pulled over for drunken driving, Schmahmann says. "The state
trooper test is a test of cerebellar function. So the effect of alcohol on
cerebellar function is identified by everybody who's ever done walking a
straight line or touching their finger to the nose."
But Schmahmann and a small group of other scientists have
spent decades building a case that the cerebellum does a lot more than let
people pass a sobriety test.
First, they showed that it has connections to brain areas
that perform higher functions, like using language, reading maps and planning.
Then, a few years ago, researchers began to do functional MRI studies that
suggested that the cerebellum was actively involved in these tasks.
"The big surprise from functional imaging was that when
you do these language tasks and spatial tasks and thinking tasks, lo and behold
the cerebellum lit up," Schmahmann says.
Some of the most compelling evidence, though, has come from
research on a handful of people who have no cerebellum, people like Jonathan
Keleher.
For the first few years, his future looked highly uncertain,
says his mother, Catherine. "All his milestones were late: sitting up,
walking, talking."
But during that time doctors and developmental health
experts still didn't know why Jonathan was having so much trouble. And that
turned out to be a good thing, says his father, Richard. "Not knowing what
the diagnosis was we said, 'Well, let's assume he can do everything,' " he
says.
So Jonathan got special education, speech therapy and
physical therapy. His father even came up with a sort of beach therapy.
"He wasn't walking," Richard says. "And I
found that if I took him to the beach, he would try to walk."
Jonathan was 5 when a brain scan finally revealed the
problem. And eventually he was referred to Schmahmann, who has spent his entire
career studying the cerebellum.
n image of Jonathan's brain is on a computer screen the day
I visit Schmahmann's lab. He points to an area just above the brain stem.
"He has this remarkable black space down here, which is where the
cerebellum is supposed to be," Schmahmann says. "It's a very big area
of nothingness there."
Research on Jonathan and people like him supports the idea
that the cerebellum really has just one job: It takes clumsy actions or
functions and makes them more refined. "It doesn't make things. It makes
things better," Schmahmann says.
That's pretty straightforward when it comes to movement. The
brain's motor cortex tells your legs to start walking. The cerebellum keeps
your stride smooth and steady and balanced.
"What we now understand is what that cerebellum is
doing to movement, it's also doing to intellect and personality and emotional
processing," Schmahmann says.
Unless you don't have a cerebellum. Then, Schmahmann says, a
person's thinking and emotions can become as clumsy as their movements.
Jonathan got a reminder of this at a busy intersection soon
after he got his driver's license. There was a bus behind him, cars whizzing
by, and his brain simply couldn't coordinate all the information. So he totaled
his father's car.
"Reaction time, not my strong suit," Jonathan
says, adding that he doesn't drive anymore.
Emotional complexity is another challenge for Jonathan, says
his sister, Sarah Napoline. She says her brother is a great listener, but isn't
introspective.
"He doesn't really get into this deeper level of
conversation that builds strong relationships, things that would be the
foundation for a romantic relationship or deep enduring friendships," she
says. Jonathan, who is sitting beside her, says he agrees.
Jonathan also needed to be taught a lot of things that
people with a cerebellum learn automatically, Sarah says: how to speak clearly,
how to behave in social situations and how to show emotion.
Yet Jonathan is now able to do all of those things. He's
done it by training other areas of his brain to do the jobs usually done by the
cerebellum, Schmahmann says.
It's taken decades, Richard says. He adds that it couldn't
have happened at all if his son were less resilient and determined.
"There are times when I realize how brave my son has
been," he says. "Being out there on his own, going down to the beach
and falling down again and again and again and again. It's pretty
impressive."
No comments:
Post a Comment