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The effect of long-term unilateral deafness on the activation pattern in the auditory cortices of French-native speakers: influence of deafness side.

Hanss J, Veuillet E, Adjout K, Besle J, Collet L, Thai-Van H - BMC Neurosci (2009)

Bottom Line: This was observed not only for AEP amplitudes but also for AEP time course.This suggests that anatomical and functional plastic changes are more likely to occur in the right than in the left auditory cortex.The possible perceptual correlates of such neurophysiological changes are discussed.

View Article: PubMed Central - HTML - PubMed

Affiliation: Université de Lyon, Lyon, F-69003, France. julien.hanss@hotmail.fr

ABSTRACT

Background: In normal-hearing subjects, monaural stimulation produces a normal pattern of asynchrony and asymmetry over the auditory cortices in favour of the contralateral temporal lobe. While late onset unilateral deafness has been reported to change this pattern, the exact influence of the side of deafness on central auditory plasticity still remains unclear. The present study aimed at assessing whether left-sided and right-sided deafness had differential effects on the characteristics of neurophysiological responses over auditory areas. Eighteen unilaterally deaf and 16 normal hearing right-handed subjects participated. All unilaterally deaf subjects had post-lingual deafness. Long latency auditory evoked potentials (late-AEPs) were elicited by two types of stimuli, non-speech (1 kHz tone-burst) and speech-sounds (voiceless syllable/pa/) delivered to the intact ear at 50 dB SL. The latencies and amplitudes of the early exogenous components (N100 and P150) were measured using temporal scalp electrodes.

Results: Subjects with left-sided deafness showed major neurophysiological changes, in the form of a more symmetrical activation pattern over auditory areas in response to non-speech sound and even a significant reversal of the activation pattern in favour of the cortex ipsilateral to the stimulation in response to speech sound. This was observed not only for AEP amplitudes but also for AEP time course. In contrast, no significant changes were reported for late-AEP responses in subjects with right-sided deafness.

Conclusion: The results show that cortical reorganization induced by unilateral deafness mainly occurs in subjects with left-sided deafness. This suggests that anatomical and functional plastic changes are more likely to occur in the right than in the left auditory cortex. The possible perceptual correlates of such neurophysiological changes are discussed.

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Inter-hemispheric amplitude difference for N1-P2 complex over the posterior temporal lobes (electrodes T5 and T6) in response to the unvoiced syllable/pa/. The LD-r group shows a significant reversed asymmetry in favour of the ipsilateral cortex (healthy-side dominance) compared with NH-r controls.
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Figure 5: Inter-hemispheric amplitude difference for N1-P2 complex over the posterior temporal lobes (electrodes T5 and T6) in response to the unvoiced syllable/pa/. The LD-r group shows a significant reversed asymmetry in favour of the ipsilateral cortex (healthy-side dominance) compared with NH-r controls.

Mentions: In order to simplify presentation of the results, data are shown separately for each group of subjects. Figure 4 and Table 1 show, respectively, the individual and mean values of N1 latency over the temporal lobes ipsilateral and contralateral to the stimulation and the corresponding N1 IHLD mean values, for each stimulus. Table 2 shows N1-P2 complex amplitude mean values over the temporal lobes ipsilateral and contralateral to the stimulation and corresponding IHAD mean values, relative to each stimulus. Figure 5 shows IHAD mean values in response to the unvoiced syllable/pa/.


The effect of long-term unilateral deafness on the activation pattern in the auditory cortices of French-native speakers: influence of deafness side.

Hanss J, Veuillet E, Adjout K, Besle J, Collet L, Thai-Van H - BMC Neurosci (2009)

Inter-hemispheric amplitude difference for N1-P2 complex over the posterior temporal lobes (electrodes T5 and T6) in response to the unvoiced syllable/pa/. The LD-r group shows a significant reversed asymmetry in favour of the ipsilateral cortex (healthy-side dominance) compared with NH-r controls.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2662863&req=5

Figure 5: Inter-hemispheric amplitude difference for N1-P2 complex over the posterior temporal lobes (electrodes T5 and T6) in response to the unvoiced syllable/pa/. The LD-r group shows a significant reversed asymmetry in favour of the ipsilateral cortex (healthy-side dominance) compared with NH-r controls.
Mentions: In order to simplify presentation of the results, data are shown separately for each group of subjects. Figure 4 and Table 1 show, respectively, the individual and mean values of N1 latency over the temporal lobes ipsilateral and contralateral to the stimulation and the corresponding N1 IHLD mean values, for each stimulus. Table 2 shows N1-P2 complex amplitude mean values over the temporal lobes ipsilateral and contralateral to the stimulation and corresponding IHAD mean values, relative to each stimulus. Figure 5 shows IHAD mean values in response to the unvoiced syllable/pa/.

Bottom Line: This was observed not only for AEP amplitudes but also for AEP time course.This suggests that anatomical and functional plastic changes are more likely to occur in the right than in the left auditory cortex.The possible perceptual correlates of such neurophysiological changes are discussed.

View Article: PubMed Central - HTML - PubMed

Affiliation: Université de Lyon, Lyon, F-69003, France. julien.hanss@hotmail.fr

ABSTRACT

Background: In normal-hearing subjects, monaural stimulation produces a normal pattern of asynchrony and asymmetry over the auditory cortices in favour of the contralateral temporal lobe. While late onset unilateral deafness has been reported to change this pattern, the exact influence of the side of deafness on central auditory plasticity still remains unclear. The present study aimed at assessing whether left-sided and right-sided deafness had differential effects on the characteristics of neurophysiological responses over auditory areas. Eighteen unilaterally deaf and 16 normal hearing right-handed subjects participated. All unilaterally deaf subjects had post-lingual deafness. Long latency auditory evoked potentials (late-AEPs) were elicited by two types of stimuli, non-speech (1 kHz tone-burst) and speech-sounds (voiceless syllable/pa/) delivered to the intact ear at 50 dB SL. The latencies and amplitudes of the early exogenous components (N100 and P150) were measured using temporal scalp electrodes.

Results: Subjects with left-sided deafness showed major neurophysiological changes, in the form of a more symmetrical activation pattern over auditory areas in response to non-speech sound and even a significant reversal of the activation pattern in favour of the cortex ipsilateral to the stimulation in response to speech sound. This was observed not only for AEP amplitudes but also for AEP time course. In contrast, no significant changes were reported for late-AEP responses in subjects with right-sided deafness.

Conclusion: The results show that cortical reorganization induced by unilateral deafness mainly occurs in subjects with left-sided deafness. This suggests that anatomical and functional plastic changes are more likely to occur in the right than in the left auditory cortex. The possible perceptual correlates of such neurophysiological changes are discussed.

Show MeSH
Related in: MedlinePlus