Deaf develop sense of touch differently

People who are born deaf process the sense of touch differently than people born with normal hearing, U.S. researchers said. Christina M. Karns, a postdoctoral research associate in the Brain Development Lab at the University of Oregon in Eugene, and colleagues showed 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, published in The Journal of Neuroscience, 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. Karns and colleagues developed a unique apparatus that could be worn like headphones while subjects were in a magnetic resonance imaging scanner. Flexible tubing, connected to a compressor in another room, delivered soundless puffs of air above the right eyebrow and to the cheek below the right eye, Karns said. Visual stimuli -- brief pulses of light -- were delivered via fiber optic cables mounted directly below the air-puff nozzle and the functional MRI was used to measure reactions to the stimuli in Heschl's gyrus, the site of the primary auditory cortex in the human brain's temporal lobe as well as other brain areas. There are several ways the finding might 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, Karns said.