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Scientists: One brain cell may reverse muscle paralysis

Oct. 15, 2008
Courtesy Nature
and World Science staff

Ac­tiva­t­ion of a sin­gle brain cell may be enough to help re­store mus­cle ac­ti­vity in the arms of par­a­lysed pa­tients with spi­nal cord in­ju­ries, sci­en­tists say.

Chet Mo­ritz of the Uni­ver­s­ity of Wash­ing­ton and col­leagues re-routed con­trol sig­nals from the brains of tem­po­rarily par­a­lysed mon­keys di­rectly to their mus­cles. The brain re­gion uti­lized was an ar­ea known as the mo­tor cor­tex, which con­trols move­ments.

The re­search, pub­lished in the Oct. 16 is­sue of the re­search jour­nal Na­ture, has po­ten­tial for the fu­ture treat­ment of spi­nal cord in­ju­ry, stroke and oth­er im­pair­ments af­fect­ing move­ment, ac­cord­ing to the group.

The re­search­ers ex­plained that they cre­at­ed ar­ti­fi­cial path­ways for the sig­nals to pass down. As a re­sult, mus­cles that lacked nat­u­ral stimula­t­ion af­ter pa­ral­y­sis re­gained a flow of elec­tri­cal sig­nals from the brain. The mon­keys were then able to tense the mus­cles in the par­a­lysed arm, a first step to­wards pro­duc­ing more com­pli­cat­ed goal-di­rected move­ments.

The team ar­gues that a neu­ron, or brain cell, pre­vi­ously not as­so­ci­at­ed with move­ment could be “co-opted” to as­sume a new con­trol role. This has im­plica­t­ions for fu­ture brain-machine in­ter­face machines, de­vices de­signed to trans­late thoughts in­to phys­i­cal move­ments by har­ness­ing the elec­tri­cal ac­ti­vity of neu­rons.

Brain-machine in­ter­faces are an im­por­tant tool for the study of brain in­ju­ry and mo­tor con­trol, but the machines have so far fo­cused on ex­ploit­ing popula­t­ions of neu­rons rath­er than sin­gle cells, Mo­ritz and col­leagues not­ed.

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Activation of a single brain cell may be enough to help restore muscle activity in the arms of paralysed patients with spinal cord injuries, scientists say. Chet Moritz of the University of Washington and colleagues re-routed control signals from the brains of temporarily paralysed monkeys directly to their muscles. The brain region utilized was an area known as the motor cortex, which controls movements. The research, published in the Oct. 16 issue of the research journal Nature, has potential for the future treatment of spinal cord injury, stroke and other impairments affecting movement, according to the group. The researchers explained that they created artificial pathways for the signals to pass down. As a result, muscles that lacked natural stimulation after paralysis regained a flow of electrical signals from the brain. The monkeys were then able to tense the muscles in the paralysed arm, a first step towards producing more complicated goal-directed movements. The team argues that a neuron, or brain cell, previously not associated with movement could be “co-opted” to assume a new control role. This has implications for future brain-machine interface machines, devices designed to translate thoughts into physical movements by harnessing the electrical activity of neurons. Brain-machine interfaces are an important tool for the study of brain injury and motor control, but the machines have so far focused on exploiting populations of neurons rather than single cells, Moritz and colleagues noted.