The investigators next examined brain tissue from the mice and found a decrease in astrocytes, but not other cell types, in the mice with the genetic mutation compared to mice without the mutation. Astrocytes play a critical role in supporting nerve cells by carrying out a wide range of functions, such as supplying them with oxygen and nutrients and providing structural support. The loss of astrocytes was more pronounced in the corpus callosum of the mutant mice. In addition, using advanced magnetic resonance imaging (MRI) methods, the researchers detected reduced local volume of the corpus callosum in the mutant mice despite normal diffusion tensor MRI values, providing further support for a defect in this brain region.
Containing as many as 200 million nerve fibers, the corpus callosum enables communication between the brain’s left and right hemispheres, helping to integrate signals for processes that involve both hemispheres, such as physical coordination and use of language.
Follow-up experiments in which the GNPTAB human stuttering mutation was introduced into individual brain cell types—rather than the entire mouse—confirmed that the vocalization defect is specific to astrocytes. The mice did not have the stuttering-like vocalizations when the mutation was engineered into other types of brain cells.
If future research confirms that stuttering in people with GNPTAB mutations derives from a loss of astrocytes in the brain, these findings could open the door to new therapeutic strategies for some people with persistent developmental stuttering by targeting associated molecular pathways and cells.
This press release describes a basic research finding. Basic research increases our understanding of human behavior and biology, which is foundational to advancing new and better ways to prevent, diagnose, and treat disease. Science is an unpredictable and incremental process — each research advance builds on past discoveries, often in unexpected ways. Most clinical advances would not be possible without the knowledge of fundamental basic research.
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This research was supported by the Intramural Research Program at the National Institute on Deafness and other Communication Disorders (Z1A-000046- 18). The NIH’s National Institute of Mental Health and National Heart, Lung, and Blood Institute also contributed support.
About the National Institute on Deafness and Other Communication Disorders (NIDCD): The NIDCD supports and conducts research and research training on the normal and disordered processes of hearing, balance, taste, smell, voice, speech, and language and provides health information, based upon scientific discovery, to the public.
About the National Institutes of Health (NIH): NIH, the nation's medical research agency, includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. NIH is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit
www.nih.gov.
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