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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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Related in: MedlinePlus

Individual late-AEPs recorded from 29 scalp electrodes in response to 1 kHz tone burst and unvoiced syllable/pa/(data from one normal hearing subject stimulated on the left ear). The analysis is focused on the temporal electrodes (which exhibit a reversed waveform compared with Cz).
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Figure 2: Individual late-AEPs recorded from 29 scalp electrodes in response to 1 kHz tone burst and unvoiced syllable/pa/(data from one normal hearing subject stimulated on the left ear). The analysis is focused on the temporal electrodes (which exhibit a reversed waveform compared with Cz).

Mentions: Scalp-EEG activity was recorded from 29 electrodes embedded in an electrode cap and placed in accordance with the international reference system (standard IFCN for digital recording of clinical EEGs: Fp1, Fp2, F7, F8, F3, Fz, F4, FC5, FC6, FC1, FC2, T3, C3, Cz, C4, T4, CP5, CP6, M1, M2, P3, Pz, P4, T5, T6, OM1, OM2, O1, O2 (see Figure 2)) using Micromed System Plus 98® software. All electrodes were referenced to the tip of the nose and an electrode on the forehead served as the ground. Eye movements were monitored with a bipolar electrode montage. Impedance was maintained below 5 kΩ. Evoked potentials were recorded at a digitization rate of 1024 Hz as single epochs over an analysis window of 600 ms, which included 100 ms prior to presentation of the stimulus. Synchronous digital marking of the acoustic stimuli was obtained by connecting devices for EEG recording and auditory stimulation (Micromed trigger box).


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)

Individual late-AEPs recorded from 29 scalp electrodes in response to 1 kHz tone burst and unvoiced syllable/pa/(data from one normal hearing subject stimulated on the left ear). The analysis is focused on the temporal electrodes (which exhibit a reversed waveform compared with Cz).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 2: Individual late-AEPs recorded from 29 scalp electrodes in response to 1 kHz tone burst and unvoiced syllable/pa/(data from one normal hearing subject stimulated on the left ear). The analysis is focused on the temporal electrodes (which exhibit a reversed waveform compared with Cz).
Mentions: Scalp-EEG activity was recorded from 29 electrodes embedded in an electrode cap and placed in accordance with the international reference system (standard IFCN for digital recording of clinical EEGs: Fp1, Fp2, F7, F8, F3, Fz, F4, FC5, FC6, FC1, FC2, T3, C3, Cz, C4, T4, CP5, CP6, M1, M2, P3, Pz, P4, T5, T6, OM1, OM2, O1, O2 (see Figure 2)) using Micromed System Plus 98® software. All electrodes were referenced to the tip of the nose and an electrode on the forehead served as the ground. Eye movements were monitored with a bipolar electrode montage. Impedance was maintained below 5 kΩ. Evoked potentials were recorded at a digitization rate of 1024 Hz as single epochs over an analysis window of 600 ms, which included 100 ms prior to presentation of the stimulus. Synchronous digital marking of the acoustic stimuli was obtained by connecting devices for EEG recording and auditory stimulation (Micromed trigger box).

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