MedicalResearch.com Interview with:
Niki Katerina Vavatzanidis MSc
Department of Neuropsychology
Max Planck Institute for Human and Cognitive Brain Science
Technische Universität Dresden, Germany
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: Cochlear implants (CIs) are a way of providing hearing to sensorineural deaf individuals. The implant works by first picking up sounds from the environment and transforming them into an electric signal. Via an array of electrodes the implant then transmits the signal directly to the auditory nerve, which then leads to auditory sensations in the brain.
In our study, we were interested to see how language acquisition is affected when language immersion occurs at an untypically late age. Children with cochlear implants that grow up in exclusively or predominantly hearing environments will have their first language encounter at the time of implantation, which nowadays is roughly between the age of one and three. Besides the later starting point in language acquisition, children with CIs are facing a compromised input quality compared to typical hearing.
We know from typically hearing children that it is around the age of 14 months that their vocabulary becomes robust enough to react to name violations. That is, when a picture is labelled incorrectly, their brain waves will display with the so-called N400 effect. In our study we were interested whether children with CIs would also show the N400 effect and if so, how many months of hearing experience are necessary. We measured the brain activity of children implanted between the age of one and four at three time points: 12, 18, and 24 months after implant activation. To our surprise, congenitally deaf children whose only language input had been via the cochlear implant already displayed the N400 effect after 12 months of language immersion, i.e. earlier than seen in typically hearing children. Continue reading