Rare Movement Disorder Explored
NEW YORK, January 30, 2001 (Reuters Health) - Scientists have
identified a key protein that is essential for normal transmission of
impulses from the brain to the limbs in mice allowing for the separate
movement of their legs, according to a report in the January issue of
the journal Neuron.
Mice genetically engineered not to produce a protein called ephrin-B3
developed the unusual condition called ``mirror movement'' disorder.
Although the disorder is ``quite rare'' in humans, those who suffer it
are unable to move only their right hand separately from the left, for
instance, explained lead researcher Dr. Mark Henkemeyer, of the
University of Texas Southwestern Medical Center at Dallas, in an
interview with Reuters Health.
"It was known that ephrin-B3 is found in a column, two-cells thick, that
runs down the very center of the spine,'' Henkemeyer told Reuters
Health. ``We believe that as electronic impulses are sent from the left
side of the brain, they cross through this ephrin-B3 barrier to the
right side of the spinal cord.''
The line of ephrin-B3 essentially acts to create a barrier so impulses
pass through to the opposite side of the spinal cord from the respective
controlling brain hemisphere. (The left side of the brain generally
controls the right side of the body and vice versa.) When the barrier is
removed, as in the case of the defective mice, the impulses are able to
travel freely to both sides of the spinal cord resulting in the movement
of both sides of limbs, Henkemeyer explained.
Mice born without any ephrin-B3 were unable to walk with a normal gate;
the right legs stepping forward followed by the left legs and so on.
Instead they moved about in short hopping motions similar to a kangaroo,
according to Henkemeyer.
Henkemeyer and his colleagues hope that their research brings greater
understanding about how the brain is connected to the spinal cord and
how the connection allows for voluntary control of movement.
SOURCE: Neuron January 2001.
Email this story - View most popular | Printer-friendly format
Copyright © 2001 Yahoo! Inc., and Reuters Limited.
--
Judith Richards, London, Ontario, Canada
[log in to unmask]
Today’s Research...
Tomorrow’s Cure
