Myelin Suppresses Plasticity in the Mature Brain

[Guest guest]

Myelin Suppresses Plasticity in the Mature Brain

http://www.medicalnewstoday.com/medicalnews.php?newsid=31577

05 Oct 2005

Yale School of Medicine researchers report in Science this week

genetic evidence for the hypothesis that myelination, or formation of

a protective sheath around a nerve fiber, consolidates neural

circuitry by suppressing plasticity in the mature brain.

This finding has implications for research on restoring mobility to

people who have lost motor functions due to spinal cord injury,

multiple sclerosis, Lou Gehrig's disease, and other central nervous

system disorders.

" The failure of surviving neurons to reestablish functional

connection is most obvious after spinal cord injury, but limited

nerve cell regeneration and plasticity is central to a range of

neurological disorders, including stroke, head trauma, multiple

sclerosis, and neurodegenerative disease, " said senior author

Strittmatter, professor in the Departments of Neurology and

Neurobiology. " Recovery of motor function after serious damage to the

mature brain is facilitated by structural and synaptic plasticity. "

Strittmatter's laboratory studies how myelin in the central nervous

system physically limits axonal growth and regeneration after

traumatic and ischemic injury, when blood supply is cut off. A

physiological role for the myelin inhibitor pathway has not been

defined.

Blocking vision in one eye normally alters ocular dominance in the

cortex of the brain only during a critical developmental period, or

20 to 32 days postnatal in mice. Strittmatter's lab, working in

collaboration with Nigel Daw, M.D., professor of ophthalmology and

neuroscience, and his group, found that mutations in the Nogo-66

receptor (NgR) affect plasticity of ocular dominance. In mice with

altered NgR, plasticity during the critical period is normal, but it

continues abnormally so that ocular dominance later in development is

similar to the plasticity of juvenile stages.

Science (September 30, 2005)

Yale News Releases are available via the World Wide Web at

http://www.yale.edu/opa