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Altered Cortical Activity in Prelingually Deafened Cochlear Implant Users Following Long Periods of Auditory Deprivation

Contributor(s): MARC J. W. LAMMERS,1,2Material type: ArticleArticleSubject(s): cortical auditory evoked potential | deafness | cochlear implant | plasticity | auditory cortex | prelingual deaf | hearing lossOnline resources: Click here to access online In: JARO 2014Abstract: Auditory stimulation during childhood is critical for the development of the auditory cortex in humans and with that for hearing in adulthood. Age-related changes in morphology and peak latencies of the cortical auditory evoked potential (CAEP) have led to the use of this cortical response as a biomarker of auditory cortical maturation including studies of cortical development after deafness and subsequent cochlear implantation. To date, it is unknown whether prelingually deaf adults, with early onset deafness (before the age of 2 years) and who received a cochlear implant (CI) only during adulthood, would display absent or aberrant CAEP waveforms as predicted from CAEP studies in late implanted prelingually deaf children. In the current study, CAEP waveforms were recorded in response to electric stimuli in prelingually deaf adults, who received their CI after the age of 21 years. Waveform morphology and peak latencies were compared to the CAEP responses obtained in postlingually deaf adults, who became deaf after the age of 16. Unexpectedly, typical CAEP waveforms with adult-like P1-N1-P2 morphology could be recorded in the prelingually deaf adult CI users. On visual inspection, waveform morphology was comparable to the CAEP waveforms recorded in the postlingually deaf CI users. Interestingly, however, latencies of the N1 peak were significantly shorter and amplitudes were significantly larger in the prelingual group than in the postlingual group. The presence of the CAEP together with an early and large N1 peak might represent activation of the more innate and less complex components of the auditory cortex of the prelingually deaf CI user, whereas the CAEP in postlingually deaf CI users might reflect activation of the mature neural network still present in these patients. The CAEPs may therefore be helpful in the assessment of developmental state of the auditory cortex.
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Auditory stimulation during childhood is critical for
the development of the auditory cortex in humans
and with that for hearing in adulthood. Age-related
changes in morphology and peak latencies of the
cortical auditory evoked potential (CAEP) have led to
the use of this cortical response as a biomarker of
auditory cortical maturation including studies of
cortical development after deafness and subsequent
cochlear implantation. To date, it is unknown whether
prelingually deaf adults, with early onset deafness
(before the age of 2 years) and who received a
cochlear implant (CI) only during adulthood, would
display absent or aberrant CAEP waveforms as predicted
from CAEP studies in late implanted
prelingually deaf children. In the current study,
CAEP waveforms were recorded in response to
electric stimuli in prelingually deaf adults, who
received their CI after the age of 21 years. Waveform
morphology and peak latencies were compared to the
CAEP responses obtained in postlingually deaf adults,
who became deaf after the age of 16. Unexpectedly,
typical CAEP waveforms with adult-like P1-N1-P2
morphology could be recorded in the prelingually
deaf adult CI users. On visual inspection, waveform
morphology was comparable to the CAEP waveforms
recorded in the postlingually deaf CI users.
Interestingly, however, latencies of the N1 peak were
significantly shorter and amplitudes were significantly
larger in the prelingual group than in the postlingual
group. The presence of the CAEP together with an
early and large N1 peak might represent activation of
the more innate and less complex components of the
auditory cortex of the prelingually deaf CI user, whereas
the CAEP in postlingually deaf CI users might reflect
activation of the mature neural network still present in
these patients. The CAEPs may therefore be helpful in
the assessment of developmental state of the auditory
cortex.

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