Quadriplegics retain ability to activate sensorimotor brain areas
From: Nature 2001;413:793
By: Karla Gale

WESTPORT, CT (Reuters Health) - Attempted movement of paralyzed limbs
activates corresponding areas of motor cortex that differ little in
somatotopic organization from those in nonparalyzed subjects, according to a
brief communication in the October 25th issue of Nature. 

This finding implies, the investigators say, that an implantable
brain-computer interface device that could bypass damaged motor pathways to
reconstruct complex voluntary motor activity would be feasible for patients
with spinal cord injuries. 

Dr. Richard A. Normann, of the University of Utah in Salt Lake City, and
colleagues examined five subjects with C5-C6 trauma-related spinal-cord
damage 1 to 5 years after their injuries, along with five healthy control
subjects. All individuals were asked to move or attempt to move their hands,
elbows, feet, left knee, and lips. 

According to the results of functional magnet resonance imaging, volitional
activation of cortical sensorimotor representations in the quadriplegics
varied little from that of control subjects. The research team notes that
this response in patients with paralysis meets one of the principal
physiological requirements for the development of an implantable
neuroprosthetic that could reconstruct complex voluntary motor activity. 

In an interview with Reuters Health, Dr. Normann elaborated on his group's
findings and their potential implications. He noted that, in an unimpaired
individual, firing patterns of neurons in the motor cortex differ, for
example, when one makes a fist and then opens the hand, or when different
fingers are raised. 

"We showed that a spinal cord-injured individual who is not able to cause
movement can still think the same thoughts that activate the hand
representation or the finger representation, and so on," he said. "The
architectural arrangement and function of the motor cortex has been preserved
even 5 years post-injury."  

He continued, "That means that one could implant an array of electrodes into
the motor cortex of a patient paralyzed by a spinal cord injury and record
the firing patterns there. Then the person could modulate or control the
firing pattern just by volitional thought. We would amplify those signals and
send them out to a computer and use those recorded signals to control an
external device, such as a wheelchair or a computer terminal or a robotic
arm."

http://www.nature.com/cgi-taf/DynaPage.taf?file=/nature/journal/v413/n6858/abs/413793a0_fs.html

http://www.nature.com/cgi-taf/DynaPage.taf?file=/nature/journal/v413/n6858/full/413793a0_fs.html

http://www.nature.com/cgi-taf/DynaPage.taf?file=/nature/journal/v413/n6858/full/413793a0_fs.html&content_filetype=PDF

http://www.bioen.utah.edu/faculty/RAN/