New research funded by the National Institutes of Health (NIH) shows that people who are born deaf process the sense of touch differently than people who are born with normal hearing, The finding reveals how the early loss of a sense, such as hearing, can affect brain development.

The study, published in The Journal of Neuroscience, was conducted by a team led by Christina M. Karns, PhD, a postdoctoral research associate in the Brain Development Lab at the University of Oregon, Eugene, and her colleagues.

According to the authors, deaf people use the auditory cortex to process touch stimuli and visual stimuli to a much greater degree than occurs in hearing people. The finding suggests that since the developing auditory cortex of profoundly deaf people is not exposed to sound stimuli, it adapts and takes on additional sensory processing tasks.

There are several ways the finding may help deaf people. For example, if touch and vision interact more in the deaf, touch could be used to help deaf students learn math or reading. The finding also has the potential to help clinicians improve the quality of hearing after cochlear implants, especially among congenitally deaf children who are implanted after the ages of 3 or 4. These children, who have lacked auditory input since birth, may struggle with comprehension and speech because their auditory cortex has taken on the processing of other senses, such as touch and vision. These changes may make it more challenging for the auditory cortex to recover auditory processing function after cochlear implantation. Being able to measure how much the auditory cortex has been taken over by other sensory processing could offer doctors insights into the kinds of intervention programs that would help the brain retrain and devote more capacity to auditory processing.

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