Almost two decades after the daughter of rugby league legend Wally Lewis received a cochlear implant researchers will peer inside her brain to learn how it has adapted to the life-altering hearing device.
Jamie-Lee Lewis, who was diagnosed as profoundly deaf at one year of age, is one of the first people with a cochlear implant to have their brain scanned in the world’s first cochlear MEG, or magnetoencephalography, housed at the ARC Centre of Excellence in Cognition and its Disorders at Macquarie University.
The project’s chief investigator, Blake Johnson, said while cochlear implants had improved the lives of thousands of people with severe hearing loss, there was a significant difference in the speech and hearing ability of those recipients.
“You can have two people with an identical implant and one person is able to talk on the telephone and under noisy conditions and another person can only communicate under very quiet conditions,” he said.
Scientists believed this variation in performance was caused by the brain reorganising itself when it was not exposed to sound for a period of time.
“A brain that has been deprived of speech and sound for some time has changed and when you restore hearing with an implant that may or may not restore the brain to that of a normal hearing person,” Dr Johnson said.
He said evidence of the brain's reorganisation was that the younger children with profound hearing loss were given implants, the less time they spent without sounds and the greater their chance of normal speech.
“The best practice now is to try and get children implanted before their first birthday,” Dr Johnson said.
To study these brain changes, the team will scan both children and young adults using the MEG, which measures the magnetic field pulses given off by the brain.
Dr Johnson said the machine needed to be highly sensitive to measure these tiny pulses.
“It’s like measuring the footsteps of ants on a football field,” he said.
Jamie-Lee said although her implant had been inserted after her fourth birthday, it had offered her “so many opportunities”, from socialising at parties, listening to music and even hearing her nephew talk.
“I love listening to his laughing,” she said.
Dr Johnson also planned to study how the adult brain responded to hearing loss. Deafness is more common in old age, along with an increase risk of cognitive decline or dementia, he said.
“There is a lot of interest in the connections of those two and one possibility is that hearing loss directly impacts cognitive decline,” he said.
“This is an enormous issue for society as the population ages."