Kennedy Krieger Researchers Discover Cellular Behavior that Reveals New Insights into Nerve Function

Kat Szeto,'s picture
November 02, 2015
Discovery Could Improve Understanding of Neurodegenerative Diseases

Baltimore, MD – Researchers at the Kennedy Krieger Institute have made a new discovery about the biological functioning of myelin segments, the insulating shields that protect nerve fibers. The study, published in the Proceedings of the National Academy of Sciences, found that healthy myelin segments grow and shorten in ways previously unknown. The findings could improve the understanding of neurodegenerative diseases, including glaucoma and multiple sclerosis.

"These findings help us understand more about the biology of our nervous system,” explains Nicholas Marsh-Armstrong, Ph.D., senior study author and a research scientist at the Kennedy Krieger Institute. “The more we know about the capacity for our nerves to change, the greater potential there is to research what relevance these changes have for neurodegenerative diseases such as glaucoma and multiple sclerosis."

In this study, Marsh-Armstrong’s team sought to learn more about the capacity for change in myelin segments by examining hundreds of fibers within the optic nerve of frogs as they are in the stage of metamorphosis. Previous research had suggested that healthy myelin segments are highly stable structures with plasticity limited to growth-related increases in thickness. However, the mechanisms involved in how myelin segments change have remained poorly understood due to the difficultly in studying how these parts of the nerve change in mammals as they age and mature. 

The study found that typical, healthy myelin segments do not just grow in thickness but are also capable of rapid shortening, which was previously unknown. This shortening, the team discovered, is the result of the myelin segments coming in contact with a unique class of cells called astrocytes. The cells remove debris along the nerve causing the myelin segments to shorten without damaging the larger structure of the nerve. Researchers believe this represents normal functioning happening within the nervous system and could contribute to other instances of myelin remolding. It also likely prevents the persistence of potentially pathological myelin dystrophies.

Future studies will examine how astrocytes affect myelin segments in mammals to further understand the relevance of myelin plasticity and how the behavior of astrocytes contribute to both normal functioning and disease states. This work advances the Kennedy Krieger Institute’s commitment to understanding how disorders of the brain, spinal cord and musculoskeletal system develop while pioneering new interventions and earlier diagnosis.

Marsh-Armstrong and other scientists at the Kennedy Krieger Institute collaborated on this study with colleagues at the Johns Hopkins University School of Medicine and the University of California. This research was supported by a Catalyst for a Cure grant from the Glaucoma Research Foundation, with additional grants from the National Center for Research Resources, National Institute on Drug Abuse Human Brain Project and National Institute of General Medical Sciences.


Internationally recognized for improving the lives of children and adolescents with disorders and injuries of the brain, spinal cord and musculoskeletal system, the Kennedy Krieger Institute in Baltimore, MD, serves more than 20,000 individuals each year through inpatient and outpatient clinics, home and community services and school-based programs. Kennedy Krieger provides a wide range of services for children with developmental concerns mild to severe, and is home to a team of investigators who are contributing to the understanding of how disorders develop while pioneering new interventions and earlier diagnosis. For more information on the Kennedy Krieger Institute, visit

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