Transcranial Magnetic Stimulation Update
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SCIENTIST BOMBARDS BRAINS WITH SUPER-MAGNETS TO EDIFYING EFFECT
By Carey Goldberg
January 14, 2003
Just by pointing his super-magnets at the right spots on your head, Dr.
Alvaro Pascual-Leone can make you go momentarily mute or blind.
He can disrupt your working memory or your ability to recognize faces. He
can even make it harder for you to say verbs while nouns remain as easy as
Weird, yes. Fringe, no.
Pascual-Leone is one of the premier scientific pioneers exploring a new
technique called transcranial magnetic stimulation, or TMS, which shuts down
or revs up the electrical doings inside the brain by sending a potent
magnetic field through the skull.
This is no try-it-at-home parlor trick and no ''Relieve your Pain!''
magnetic bracelet or insole.
Invented in 1985, modern-day magnetic stimulators charge up to a whopping
3,000 volts and produce peak currents of up to 8,000 amps -- powers similar
to those of a small nuclear reactor.
That pulse of current flowing from a capacitor into a hand-held coil creates
a magnetic field outside the patient's head. The field painlessly induces a
current inside the brain, affecting the electrical activity that is the
basis for all it does.
The promise of TMS as a scientific tool seems similarly powerful. And it has
generated a range of intriguing practical effects as well, from improving
attention to combating depression, that have been published in reputable,
''From the point of view of cognitive neuroscience -- understanding how
brain activity relates to behavior -- it is, in a way, a dream come true for
all of us, because it provides a way to create our own patients, as it
were,'' said Pascual-Leone, director of the Laboratory for Magnetic Brain
Stimulation at Beth Israel Deaconess Medical Center. ''You can create a very
transient disruption of the brain. For a few milliseconds, it is as if those
cells were not there. So you are able to ask questions about what role a
particular brain part plays in a particular behavior.''
More and more, TMS also appears to hold the potential for therapy to help
with brain problems, including depression, Parkinson's Disease and stroke.
Evidence, including a seminal paper by Pascual-Leone in 1996, has been
mounting that repeated sessions of TMS can alleviate recalcitrant cases of
depression, and without the nasty side effects of electroshock treatment.
Hundreds of studies in the past decade have explored myriad potential TMS
targets, including schizophrenia and post-traumatic stress disorder. Most
recently, a small study published last month found that applying TMS to
parts of the brain involved in processing sound could temporarily reduce the
endless buzzing-in-the-ears of tinnitus.
Pascual-Leone and his colleagues plan to try TMS next month on patients
whose ability to speak has been damaged by stroke. Preliminary work
indicates that their brains, in trying to repair the damage, may have
rewired themselves wrong. So blocking certain areas can actually help the
patients speak better, he said.
He has a full shopping list of other projects held up only by lack of money,
including plans to expand on work using TMS to relieve chronic pain and to
speed up the learning of physical skills. For all his own obvious
excitement, Pascual-Leone's talk is constantly punctuated by caveats that
TMS is too unproven for other people to get too excited.
For the most part in those hundreds of studies, he said, he hears ''a
premature ringing of the bells. It may help some people but it risks
creating a lot of premature expectations that may not hold true in the
Still, he's not against a few flights of fancy. What if, he asked, TMS could
block the brain activity associated with lying, and witnesses would get
zapped before taking the stand? ''It opens up all kinds of cans of worms,''
Or take the question of mental enhancement. Pascual-Leone was the first to
demonstrate that TMS can not only block brain functioning, it can
temporarily enhance it as well. In some studies, TMS has appeared to improve
subjects' working memories, speed up their problem-solving, and sharpen
Might it be possible, he wondered, to pre-activate a person's brain with TMS
and enable them to learn faster? What if some day a student could rev up one
part of his brain before French class and another before a piano lesson?
TMS is far too crude and little-tried at this point to allow for such
specific interventions. Still, the military is already aiming for TMS
enhancement. Researchers at the Brain Stimulation Laboratory at the Medical
University of South Carolina announced last year that they had received a $2
million government grant to develop a TMS device -- probably a helmet -- to
sharpen the minds of sleep-deprived soldiers while they wore it.
Ultimately, Pascual-Leone said, the field will likely move in the direction
of developing such longer-term TMS devices. Already, repeated stimulations
can apparently produce effects lasting for weeks afterward, by revving up
underactive areas or quieting down overactive spots for long enough that the
changes linger even after the stimulation stops.
But these are still very early days. TMS is conveniently noninvasive --
years ago, it took electrodes inserted in an open brain to produce similar
results -- and it appears to have virtually no side effects. But there is
always risk with something so new, Pascual-Leone cautioned, in particular,
risk that it could cause some unexpected long-term harm.
Dr. John A. Cadwell of Cadwell Laboratories in Kennewick, Wash., which began
producing a commercially viable TMS machine back in 1990, agreed: ''I think
it's a good tool, but it's not one that should be sold at Wal-Mart just
Inventors had been tinkering with the application of powerful magnets to the
human brain since the end of the 19th century. But it was only in 1985 that
Dr. Anthony T. Barker, a professor of medical physics at the University of
Sheffield in England, finally created the first effective transcranial
Barker is a skeptic about any other medical claims for garden-variety
magnets, he said, but he no longer doubts that TMS can affect mood, at the
''I think it's going to be useful,'' he said. ''Whether it will be very,
very useful, only time will tell.''
Many of the initial volunteers for TMS experiments were the researchers
themselves, on the principle that they should not ask subjects to do what
they would not do themselves.
''I've probably had more zaps to my brain than anybody else on the planet,''
Barker said blithely.
The beginning was not so blithe: There were real questions about whether TMS
might induce some of the complications -- memory loss, seizures -- that
electroshock can bring.
Cadwell recalled that in the early days of testing a TMS machine, ''No one
knew if we were going to be the next one to have a seizure, or if 12 years
of medical residency would suddenly get blown away.''
TMS did induce several seizures in participants in the early years, but
researchers have since worked out technical safety rules that prevent them
and established that no significant memory loss occurs.
Pascual-Leone, 41, who did the first TMS safety study and wrote the first
paper on TMS ethics, has zapped himself countless times, too. The zapping
looks strange but not scary: When a post-doctoral student, Yukiyasu
Kamitani, sat for a dress rehearsal of a TMS experiment the other day, it
sounded like nothing more than a bag of microwave popcorn on its final pops,
and felt, Kamitani said, like someone was lightly flicking his scalp.
Still, though TMS is already starting to be offered in Canada (see
<http://www.mindcarecentres.com>), it appears unlikely that it will arrive
soon in American clinics.
Cadwell, the American manufacturer, said that TMS devices are approved for
clinical use in most other countries, but not by the FDA. So, he said,
pronouncing the ultimate clinical death knell, ''It's not a billable
RELATED NHNE NEWS LIST ARTICLES:
THE NO-DOZE SOLDIER (12/19/2002):
WHAT BUDDHISTS KNOW ABOUT SCIENCE (7/24/2002):
MORE ON "TRANSCRANIAL MAGNETIC STIMULATION" (6/29/2002):
TMS HAT SEEKS TO PRODUCE SAVANT ABILITIES (4/19/2002):
TMS: TRANSCRANIAL MAGNETIC STIMULATION (4/18/2002):
THE BIOLOGICAL COMPONENTS OF SPIRITUAL EXPERIENCES (5/9/2001):
IN SEARCH OF GOD: SPECIAL HELMET LETS YOU MEET GOD (4/20/2001):
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