Source analysis reveals plasticity in the auditory cortex: Evidence for reduced hemispheric asymmetries following unilateral deafness

Maslin, Michael; Munro, Kevin J.; El‐Deredy, Wael

doi:10.1016/j.clinph.2012.07.016

Cited by 23 publications

(30 citation statements)

References 30 publications

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“…Our prior MEGI analysis showed loss of this interhemispheric latency difference in SSD . Studies using EEG show similar reduction in hemispheric asymmetry in SSD for dipole source strength and latency …”

Section: Discussionsupporting

confidence: 56%

“…Using MEGI, SSD subjects with chronic unilateral deafness displayed auditory cortical temporal plasticity and dipole amplitude changes compared to normal hearing subjects . Consistent with those findings, EEG and fMRI have demonstrated abnormally increased symmetry of response latency and amplitude strength in both auditory cortices over the first 2 years of adult‐onset SSD …”

Section: Introductionsupporting

confidence: 65%

“…Cortical plasticity of neural response latency and amplitude has been described in cohorts with SSD and asymmetric hearing loss. [22][23][24]27 In normal hearing adults, cortical responses to auditory stimuli demonstrate bilateral hemisphere activation with dominance of the contralateral pathway. Contralateral hemisphere activation has shorter latencies and larger amplitudes compared to the ipsilateral hemisphere.…”

Section: Discussionmentioning

confidence: 99%

“…22,23 Consistent with those findings, EEG and fMRI have demonstrated abnormally increased symmetry of response latency and amplitude strength in both auditory cortices over the first 2 years of adultonset SSD. [24][25][26][27] Although human brain imaging studies have shown cortical temporal plasticity in SSD, 22 there is not yet a human study to complement animal studies of spatial plasticity in asymmetric sensorineural hearing loss. Here, we leverage MEGI advances over the past decade, specifically superior localization of neural populations responsible for scalp-level changes in magnetic field activity, to measure cortical spread of activation between 0.5 kHz to 4 kHz in SSD.…”

Section: Introductionmentioning

confidence: 99%

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Spatial plasticity of the auditory cortex in single‐sided deafness

et al. 2016

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Section: Discussionsupporting

confidence: 56%

Section: Introductionsupporting

confidence: 65%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Spatial plasticity of the auditory cortex in single‐sided deafness

et al. 2016

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“…Early second implantations are important in terms of retaining the potential to reverse the aural preference, whereas the effects were observed after more than 1 year of unilateral use (in early implantations at 1.74 years, Gordon et al, 2013; in single-sided deafness, see Scheffler et al, 1998; Bilecen et al, 2000; Langers et al, 2005; Burton et al, 2012; Maslin et al, 2013). As the greatest effects were observed in congenitally unilaterally deaf animals in the present study, before cortical synaptogenesis has set in in cats (Kral et al, 2013), implantation at ages of less than 1 year of life (peak of synaptogenesis between 1 and 4 years, comparison cat-human in Kral and O'Donoghue, 2010) can be expected to generate substantially larger effects in children than those described to date.…”

Section: Discussionmentioning

confidence: 99%

Unilateral hearing during development: hemispheric specificity in plastic reorganizations

Kral¹,

Heid²,

Hubka³

et al. 2013

Front. Syst. Neurosci.

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The present study investigates the hemispheric contributions of neuronal reorganization following early single-sided hearing (unilateral deafness). The experiments were performed on ten cats from our colony of deaf white cats. Two were identified in early hearing screening as unilaterally congenitally deaf. The remaining eight were bilaterally congenitally deaf, unilaterally implanted at different ages with a cochlear implant. Implanted animals were chronically stimulated using a single-channel portable signal processor for two to five months. Microelectrode recordings were performed at the primary auditory cortex under stimulation at the hearing and deaf ear with bilateral cochlear implants. Local field potentials (LFPs) were compared at the cortex ipsilateral and contralateral to the hearing ear. The focus of the study was on the morphology and the onset latency of the LFPs. With respect to morphology of LFPs, pronounced hemisphere-specific effects were observed. Morphology of amplitude-normalized LFPs for stimulation of the deaf and the hearing ear was similar for responses recorded at the same hemisphere. However, when comparisons were performed between the hemispheres, the morphology was more dissimilar even though the same ear was stimulated. This demonstrates hemispheric specificity of some cortical adaptations irrespective of the ear stimulated. The results suggest a specific adaptation process at the hemisphere ipsilateral to the hearing ear, involving specific (down-regulated inhibitory) mechanisms not found in the contralateral hemisphere. Finally, onset latencies revealed that the sensitive period for the cortex ipsilateral to the hearing ear is shorter than that for the contralateral cortex. Unilateral hearing experience leads to a functionally-asymmetric brain with different neuronal reorganizations and different sensitive periods involved.

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Rapid Increase in Neural Conduction Time in the Adult Human Auditory Brainstem Following Sudden Unilateral Deafness

Maslin

Lloyd

Rutherford

et al. 2015

JARO

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Individuals with sudden unilateral deafness offer a unique opportunity to study plasticity of the binaural auditory system in adult humans. Stimulation of the intact ear results in increased activity in the auditory cortex. However, there are no reports of changes at sub-cortical levels in humans. Therefore, the aim of the present study was to investigate changes in subcortical activity immediately before and after the onset of surgically induced unilateral deafness in adult humans. Click-evoked auditory brainstem responses (ABRs) to stimulation of the healthy ear were recorded from ten adults during the course of translabyrinthine surgery for the removal of a unilateral acoustic neuroma. This surgical technique always results in abrupt deafferentation of the affected ear. The results revealed a rapid (within minutes) reduction in latency of wave V (mean pre=6.55 ms; mean post=6.15 ms; pG0.001). A latency reduction was also observed for wave III (mean pre=4.40 ms; mean post=4.13 ms; pG0.001). These reductions in response latency are consistent with functional changes including disinhibition or/and more rapid intra-cellular signalling affecting binaurally sensitive neurons in the central auditory system. The results are highly relevant for improved understanding of putative physiological mechanisms underlying perceptual disorders such as tinnitus and hyperacusis.

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Source analysis reveals plasticity in the auditory cortex: Evidence for reduced hemispheric asymmetries following unilateral deafness

Cited by 23 publications

References 30 publications

Spatial plasticity of the auditory cortex in single‐sided deafness

Spatial plasticity of the auditory cortex in single‐sided deafness

Unilateral hearing during development: hemispheric specificity in plastic reorganizations

Rapid Increase in Neural Conduction Time in the Adult Human Auditory Brainstem Following Sudden Unilateral Deafness

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