Deaf children given implants as babies can learn to speak

London: Experiments conducted by Australian researchers have shown that brain activity in deaf cats develops normally if they are fitted with a cochlear implant shortly after birth.
Rob Shephard, of the Bionic Ear Institute in Melbourne, says that this finding may explain how deaf children given implants as babies can learn to speak almost as well as hearing children.
The researcher points out that in animals with normal hearing, sound vibrates hair cells in the inner ear and thereby trigger neurons to send impulses to the brain.
However, according to him, these hair cells are often defective in deaf animals, and cochlear implants compensate by stimulating neurons directly.
With a view to finding out how this artificial stimulation affects the brain, Shephard and his colleagues recorded electrical activity in the cortex of 17 8-month-old cats that were deaf from birth.
The researchers activated each cat's cochlear implant while monitoring their brains, reports New Scientist magazine.
They said that 10 of the cats had received the implant relatively recently, and their electrical activity was "completely scrambled", indicating that they did not perceive sound coherently: normal cortex activity is key to perceiving sound and, in humans, to developing speech.
However, in the seven cats that received implants at 8 weeks old, brain activity was similar to that in hearing cats.
A research article in the Journal of Comparative Neurology highlights the fact that some deaf people consider it to be unethical to operate on deaf babies, who would otherwise learn sign language.
But neurologist Jim Pickles, of the University of Queensland, says the latest work "increases the weight of evidence to implant children early".