Does long-term unilateral deafness change auditory evoked potential asymmetries?
ABSTRACT To investigate the long-term cortical changes in auditory evoked potential (AEP) asymmetries associated with profound unilateral deafness.
Electroencephalographic (EEG) recordings from 68 channels were used to measure auditory cortex responses to monaural stimulation from 7 unilaterally deaf patients and 7 audiogram-matched controls. Source localization of the AEP N100 response was carried out and regional source waveform amplitude and latency asymmetries were analysed for activity in the N100 latency range and for the middle latency response (MLR) range.
Asymmetry indices (contralateral-ipsilateral)/(contralateral+ipsilateral) showed that matched control subjects, like normally hearing participants, produced activity in the N100 latency range that was more contralaterally dominant for left compared to right ear stimulation. Contrary to expectation, source waveforms and asymmetry indices in the MLR and N100 latency range were similar for unilaterally deaf patients, their matched controls and a group of normally hearing participants.
Regional source waveform analysis revealed no evidence of systematic cortical changes in hemispheric asymmetries associated with long-term unilateral deafness. It is possible that a reorganization of cortical asymmetries to a 'normal' pattern had taken place in the years between deafness and testing.
Electrophysiological measures of auditory hemispheric asymmetries do not suggest long-term cortical reorganisation as a result of profound unilateral deafness.
- SourceAvailable from: Stefan Debener
[Show abstract] [Hide abstract]
- "~biocog/content/widmann/eeglab-plugins/). For the analysis of the middle-latency components, data were filtered from 20 to 80 Hz (cf., Hine et al., 2008); for the analysis of the late event-related components we used a filter range of 0.1–40 Hz. Artifact rejection was based on independent component analysis (ICA). "
ABSTRACT: Change deafness describes the failure to perceive even intense changes within complex auditory input, if the listener does not attend to the changing sound. Remarkably, previous psychophysical data provide evidence that this effect occurs independently of successful stimulus encoding, indicating that undetected changes are processed to some extent in auditory cortex. Here we investigated cortical representations of detected and undetected auditory changes using electroencephalographic (EEG) recordings and a change deafness paradigm. We applied a one-shot change detection task, in which participants listened successively to three complex auditory scenes, each of them consisting of six simultaneously presented auditory streams. Listeners had to decide whether all scenes were identical or whether the pitch of one stream was changed between the last two presentations. Our data show significantly increased middle-latency Nb responses for both detected and undetected changes as compared to no-change trials. In contrast, only successfully detected changes were associated with a later mismatch response in auditory cortex, followed by increased N2, P3a and P3b responses, originating from hierarchically higher non-sensory brain regions. These results strengthen the view that undetected changes are successfully encoded at sensory level in auditory cortex, but fail to trigger later change-related cortical responses that lead to conscious perception of change.NeuroImage 03/2013; 75. DOI:10.1016/j.neuroimage.2013.02.037 · 6.36 Impact Factor
[Show abstract] [Hide abstract]
- "First, while implanted children only received monaural stimulation, the NH subjects received binaural stimulation. While it is possible that monaural stimulation of the NH subjects could have revealed unilateral hemispheric activity, evidence inferred from previous studies revealing bilateral activity to monaural stimulation would suggest this is not the case (Hine et al., 2008; Ponton et al., 2001). "
ABSTRACT: Congenital deafness leads to atypical organization of the auditory nervous system. However, the extent to which auditory pathways reorganize during deafness is not well understood. We recorded cortical auditory evoked potentials in normal hearing children and in congenitally deaf children fitted with cochlear implants. High-density EEG and source modeling revealed principal activity from auditory cortex in normal hearing and early implanted children. However, children implanted after a critical period of seven years revealed activity from parietotemporal cortex in response to auditory stimulation, demonstrating reorganized cortical pathways. Reorganization of central auditory pathways is limited by the age at which implantation occurs, and may help explain the benefits and limitations of implantation in congenitally deaf children.Brain research 09/2008; 1239:56-65. DOI:10.1016/j.brainres.2008.08.026 · 2.83 Impact Factor
[Show abstract] [Hide abstract]
- "Whereas the former aspect was to be expected, the latter finding is surprising and in contrast to AEP peak latency asymmetries in normal (Hine & Debener, 2007) and unilateral deaf subjects (Hine et al., 2007). We speculate that this latency shift, if it can be replicated in larger CI populations, may relate to the adaptation of the auditory cortex to artificial monaural stimulation as provided by a CI device. "
ABSTRACT: Little is known about how the auditory cortex adapts to artificial input as provided by a cochlear implant (CI). We report the case of a 71-year-old profoundly deaf man, who has successfully used a unilateral CI for 4 years. Independent component analysis (ICA) of 61-channel EEG recordings could separate CI-related artifacts from auditory-evoked potentials (AEPs), even though it was the perfectly time-locked CI stimulation that caused the AEPs. AEP dipole source localization revealed contralaterally larger amplitudes in the P1-N1 range, similar to normal hearing individuals. In contrast to normal hearing individuals, the man with the CI showed a 20-ms shorter N1 latency ipsilaterally. We conclude that ICA allows the detailed study of AEPs in CI users.Psychophysiology 02/2008; 45(1):20-4. DOI:10.1111/j.1469-8986.2007.00610.x · 3.18 Impact Factor