Cross-modal plasticity and central deficiencies: the case of deafness and the use of cochlear implants

The primary objective of this chapter is to describe the consequences of central deficiencies on the neurodevelopment of children. We approach this topic from the standpoint of congenital deafness. Thus we first present the current state of knowledge on cortical reorganization following congenital deafness. The allocation of auditory cortices to other sensory systems can enhance sensory processing and therefore the cognitive functions related to them. Second, we explore the linguistic development of deaf children. Given that the English written system is speech-based, its acquisition is complex and atypical for deaf children, usually leading to poorer achievements. Next, we explore the impact of a neural prosthesis named the cochlear implant on the neurocognitive and linguistic development of deaf children. In some cases, it allows the individuals to, at least partially, regain access to the lost sense. We also comment on the specific needs of the deaf population when it comes to neuropsychological assessment. Finally, we touch on the specific context of deaf children born of deaf parents, and therefore naturally exposed to sign language as the only means of communication.