Brain Auditory Regions Reassigned for those with
Hearing Loss
Editor: It shouldn't surprise that parts of the brain that aren't used
get reassigned to do other tasks. But I was surprised to learn the tasks
to which auditory brain regions are assigned in those with hearing loss.
Here's the story from the folks at Virginia Commonwealth University.
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March 2009
Virginia Commonwealth University School of Medicine researchers have
discovered that adult animals with hearing loss actually re-route the
sense of touch into the hearing parts of the brain.
In the study, published online in the Early Edition of the Proceedings
of the National Academy of Sciences the week of March 23, the team
reported a phenomenon known as cross-modal plasticity in the auditory
system of adult animals. Cross-modal plasticity refers to the replacement
of a damaged sensory system by one of the remaining ones. In this case,
the sense of hearing is replaced with touch.
About 15 percent of American adults suffer from some form of hearing
impairment, which can significantly impact quality of life, especially in
the elderly.
"One often learns, anecdotally, that 'grandpa' simply turned off his
hearing aid because it was confusing and no longer helped. Our study
indicates that hearing deficits in adult animals result in a conversion of
their brain's sound processing centers to respond to another sensory
modality, making the interpretation of residual hearing even more
difficult," said principal investigator Alex Meredith, Ph.D., a professor
in the VCU Department of Anatomy and Neurobiology.
"Whether this becomes a positive feedback cycle of increasing hearing
difficulty is currently under investigation, but these findings raise the
possibility that even mild hearing loss in adult humans can have serious
and perhaps progressive consequences," Meredith said.
The findings provide researchers and clinicians with insight into how
the adult brain retains the ability to re-wire itself on a large scale, as
well as the factors that may complicate treatment of hearing loss with
hearing aids or cochlear implants.
The study was supported by a grant from the National Institutes of
Health.
Meredith worked with postdoctoral fellows Brian L. Allman and Leslie P.
Keniston, both in the Department of Anatomy and Neurobiology.
About VCU and the VCU Medical Center:
Virginia Commonwealth University is the largest university in Virginia
and ranks among the top 100 universities in the country in sponsored
research. Located on two downtown campuses in Richmond, VCU enrolls 32,000
students in 205 certificate and degree programs in the arts, sciences and
humanities. Sixty-five of the programs are unique in Virginia, many of
them crossing the disciplines of VCU's 15 schools and one college. MCV
Hospitals and the health sciences schools of Virginia Commonwealth
University compose the VCU Medical Center, one of the nation's leading
academic medical centers. For more, see www.vcu.edu.
