December 3, 1998
LONDONERS FIND TEST FOR BRAIN SPEED
-By Mary-Jane Egan -- Free Press Health Reporter
LONDON, Ont.--London researchers have discovered a new key to unlocking
the brain's mysteries, holding out hope for a range of brain
disorders from Lou Gehrig's and PARKINSON'S diseases to stroke and
Alzheimer's.
The breakthrough by physicist Dr. Ravi Menon and his team at Robarts
Research Institute marks a world-first in the use of
functional magnetic resonance imaging (MRI) to measure, in real time,
how long it takes the brain to process and respond to
information.
The discovery -- published in the prestigious Proceedings of the
National Academy of Sciences journal in the U.S -- is causing
a stir in scientific circles. Detecting and tracking swift deterioration
in the brains of patients with diseases such as Lou Gehrig's
have long eluded medical experts.
Armed with Canada's only four-tesla MRI (a magnet 80,000 times the
Earth's magnetic field), Menon's imaging team has
produced high-resolution video images called "mental chronometry,"
capable of measuring brain response sequences every 50
milliseconds.
While it remains a mystery why active parts of the brain use more
oxygen, Menon -- who co-developed functional MRI six
years ago -- discovered oxygen in the blood changes the MRI signal.
Using a specialized video game, blood flow responses in healthy
subjects were compared to patients with neurological disorders to
pinpoint areas of the brain where cells are breaking down and reaction
times plummeting. Changes in the brain, based on increased oxygen, light
up in colour.
The implications of the discovery are "enormous," said Mark Poznansky,
president and scientific director at Robarts.
Because a vast number of brain disorders such as Parkinsons and
epilepsy are based on "timing disruptions," Poznansky said the new
process will not only reveal the progress of a disease but create
potential for "targeted therapies," such as injecting a
drug into a particular artery.
The new images could also lead to more precise brain surgery, ensuring
only damaged tissue is removed.
Poznansky predicted the system could become a vital diagnostic tool for
early detection and quicker intervention of brain
abnormalities.
For stroke patients or others who've suffered a "brain assault," Menon
said mental chronometry will detect which therapies work and which hold
no promise.
"We've already seen this in our brain tumour patients," he said, noting
a patient is often temporarily paralysed after surgery due
to swelling.
By placing such patients in the magnet and telling them to move their
right hand, for instance, if motor areas in that part of the
brain light up, the doctor knows the paralysis is temporary. If not,
it's known the hand function won't recover and other therapies should be
pursued.
Menon said his team's discovery is a "non-invasive" extension of the
trailblazing work 60 years ago with epilepsy patients by the late Wilder
Penfield, a Canadian brain surgery pioneer. Penfield stimulated various
parts of the brain, noted patient responses and "mapped" areas
responsible for such things as emotion, memory, colour and smell.
Robarts' team is measuring those responses without cutting into the
skull.
The discovery may have legal and ethical implications, Menon noted.
Tests of Lou Gehrig's patients -- many of whom, near the end of their
fatal illness, can communicate only by blinking their eyes
-- have shown that while some have major brain damage, others have "no
cognitive damage right to the end."
That finding, Menon said, could impact decisions such as medical "do
not resuscitate" orders and living wills.
He said it would be a "question for the future" as to whether the
technology would be used to answer thorny issues such as whether a
person is "of sound mind."
Menon and assistants Joseph Gati and David Luknowsky have already
received some grants to pursue their research. But Menon says more
funding is vital to the project.
It costs $500 an hour to operate the scanner that produces the images,
and Menon's team is anxious to pursue tests on more patients.
"I think we're still learning all the implications of what this can
do," Menon said. "Most important, it's helping us understand how
the normal brain works because without a better understanding of that,
we can't understand diseases."
--
Judith Richards, London, Ontario, Canada
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