Changes in brain structure occur as a consequence of altered experience. During
maturation of the auditory nervous system, sensory deprivation is known to cause cell
loss, abnormal axonal projections, and synaptic alterations. These animal data may be
relevant to clinical observations that cochlear implants provide superior benefit for
individuals who become deaf postlingually compared with those who become deaf
prelingually. That is, implantation appears most efficacious if it occurs after functional
connections are established but before deprivation-induced changes in the central auditory
system. After this period, synaptic reorganization may underlie the diminished
effectiveness of cochlear implants.
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