Congenital Auditory Deprivation Reduces Synaptic Activity within the Auditory Cortex in a Layer-specific Manner

Kral, Andrej; Hartmann, Rainer; Tillein, Jochen; Heid, Silvia; Klinke, Rainer

doi:10.1093/cercor/10.7.714

Cited by 169 publications

(146 citation statements)

References 84 publications

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“…These studies include 2-deoxyglucose labeling and fos-like immunoreactivity (Brown and Benson, 1992;Ryan et al, 1990;Saito et al, 1999), measurement of slow-wave evoked potentials (Hartmann et al, 1997;Klinke et al, 1999;Kral et al, 2000), and measurement of activity in neurons or small groups of neurons using microelectrodes in the inferior colliculus (e.g., Black and Clark, 1980;Bonham et al, , 2006Merzenich et al, 1977;Rebscher et al, 2001;Snyder et al, 2004Snyder et al, , 2007Snyder et al, , 1990 and in the auditory cortex (e.g., Bierer and Middlebrooks, 2002;Middlebrooks and Bierer, 2002;Raggio and Schreiner, 1999). Most of these studies infer the tonotopic organization of the central areas from previous acoustic studies in normal hearing animals, whereas others use either acoustic stimulation (Black and Clark, 1980;Merzenich et al, 1977) of the contralateral cochlea or acoustic mapping prior to deafening and electrical stimulation (Snyder et al, 2004Middlebrooks and Snyder, 2007).…”

Section: Physiological Studies Of Current Focusing and Current Steeringmentioning

confidence: 99%

Current focusing and steering: Modeling, physiology, and psychophysics

Bonham

Litvak²

2008

Hearing Research

165

140

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Current steering and current focusing are stimulation techniques designed to increase the number of distinct perceptual channels available to cochlear implant (CI) users by adjusting currents applied simultaneously to multiple CI electrodes. Previous studies exploring current steering and current focusing stimulation strategies are reviewed, including results of research using computational models, animal neurophysiology, and human psychophysics. Preliminary results of additional neurophysiological and human psychophysical studies are presented that demonstrate the success of current steering strategies in stimulating auditory nerve regions lying between physical CI electrodes, as well as current focusing strategies that excite regions narrower than those stimulated using monopolar configurations. These results are interpreted in the context of perception and speech reception by CI users. Disparities between results of physiological and psychophysical studies are discussed. The differences in stimulation used for physiological and psychophysical studies are hypothesized to contribute to these disparities. Finally, application of current steering and focusing strategies to other types of auditory prostheses is also discussed.

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Section: Physiological Studies Of Current Focusing and Current Steeringmentioning

confidence: 99%

Current focusing and steering: Modeling, physiology, and psychophysics

Bonham

Litvak²

2008

Hearing Research

165

140

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“…In deaf cats, Kral et al recorded responses from different layers of the auditory cortex. They found reduced synaptic activity in the infragranular layers, which output to the other cortical regions [51]. Ponton and Eggermont [52] collected auditory evoked potentials from children who had a history of early onset, profound bilateral hearing loss and who use co-chlear implants.…”

Section: Consequences Of Early Auditory Deprivation On Development Ofmentioning

confidence: 99%

“…Early sensory deprivation and lack of auditory experience with meaningful sounds as well as speech may have a significant impact on how infants learn to interact with objects and sound sources in their environment [56]. Neuro-physiological studies provide evidence that sensory cortices are re-organized by early sensory experience [49,50] and that intercortical projections from the auditory cortex are affected by auditory deprivation [51,52].…”

Section: Attention To Speechmentioning

confidence: 99%

Speech perception skills of deaf infants following cochlear implantation: a first report

Houston

Pisoni

Kirk

et al. 2003

International Journal of Pediatric Otorhinolaryngology

104

116

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SummaryObjective-We adapted a behavioral procedure that has been used extensively with normalhearing (NH) infants, the visual habituation (VH) procedure, to assess deaf infants' discrimination and attention to speech.Methods-Twenty-four NH 6-month-olds, 24 NH 9-month-olds, and 16 deaf infants at various ages before and following cochlear implantation (CI) were tested in a sound booth on their caregiver's lap in front of a TV monitor. During the habituation phase, each infant was presented with a repeating speech sound (e.g. 'hop hop hop') paired with a visual display of a checkerboard pattern on half of the trials ('sound trials') and only the visual display on the other half ('silent trials'). When the infant's looking time decreased and reached a habituation criterion, a test phase began. This consisted of two trials: an 'old trial' that was identical to the 'sound trials' and a 'novel trial' that consisted of a different repeating speech sound (e.g. 'ahhh') paired with the same checkerboard pattern.Results-During the habituation phase, NH infants looked significantly longer during the sound trials than during the silent trials. However, deaf infants who had received cochlear implants (CIs) displayed a much weaker preference for the sound trials. On the other hand, both NH infants and deaf infants with CIs attended significantly longer to the visual display during the novel trial than during the old trial, suggesting that they were able to discriminate the speech patterns. Before receiving CIs, deaf infants did not show any preferences.Conclusions-Taken together, the findings suggest that deaf infants who receive CIs are able to detect and discriminate some speech patterns. However, their overall attention to speech sounds may be less than NH infants'. Attention to speech may impact other aspects of speech perception and spoken language development, such as segmenting words from fluent speech and learning novel words. Implications of the effects of early auditory deprivation and age at CI on speech perception and language development are discussed.

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“…The pattern of subcortical projections to primary auditory cortex in congenitally deaf cats is similar to that of normally hearing cats (4,5), suggesting that cortical auditory regions may continue to receive input from subcortical regions and might not exhibit degeneration. However, functional deficits are observed in synaptic activity and organization within auditory cortex (6), suggesting the possibility of variation in the structure of auditory cortex as a consequence of congenital deafness.…”

mentioning

confidence: 99%

A morphometric analysis of auditory brain regions in congenitally deaf adults

Emmorey

Allen

Bruss

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

190

146

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We investigated whether variation in auditory experience in humans during development alters the macroscopic neuroanatomy of primary or auditory association cortices. Volumetric analyses were based on MRI data from 25 congenitally deaf subjects and 25 hearing subjects, all right-handed. The groups were matched for gender and age. Gray and white matter volumes were determined for the temporal lobe, superior temporal gyrus, Heschl's gyrus (HG), and the planum temporale. Deaf and hearing subjects did not differ in the total volume or the gray matter volume of HG, which suggests that auditory deafferentation does not lead to cell loss within primary auditory cortex in humans. However, deaf subjects had significantly larger gray matter-white matter ratios than hearing subjects in HG, with deaf subjects exhibiting significantly less white matter in both left and right HG. Deaf subjects also had higher gray matter-white matter ratios in the rest of the superior temporal gyrus, but this pattern was not observed for the temporal lobe as a whole. These findings suggest that auditory deprivation from birth results in less myelination and͞or fewer fibers projecting to and from auditory cortices. Finally, the volumes of planum temporale and HG were significantly larger in the left hemisphere for both groups, suggesting that leftward asymmetries within ''auditory'' cortices do not arise from experience with auditory processing.T he study of congenitally deaf adults provides a unique opportunity to investigate potential changes in neural organization and structure resulting from sensory deprivation. Animal studies have shown that congenital deafness produces degenerative changes in the central auditory pathway (1, 2). Degeneration in the central auditory system subsequent to profound hearing loss has also been reported in humans. For example, Moore and colleagues (3) observed cell size reductions in the cochlear nucleus of profoundly deaf adults. However, it is unclear whether auditory deprivation from birth results in degeneration of primary auditory cortex in either animals or humans. The pattern of subcortical projections to primary auditory cortex in congenitally deaf cats is similar to that of normally hearing cats (4, 5), suggesting that cortical auditory regions may continue to receive input from subcortical regions and might not exhibit degeneration. However, functional deficits are observed in synaptic activity and organization within auditory cortex (6), suggesting the possibility of variation in the structure of auditory cortex as a consequence of congenital deafness.We investigated whether congenital and profound hearing loss in humans results in reduced volume and͞or altered morphology of cortical brain regions involved in auditory processing. Specifically, we investigated whether lack of auditory input from birth affects gray matter (GM) and white matter (WM) volumes within primary auditory cortex [defined as the transverse gyrus of Heschl (7)], within auditory association cortex in the planum temporale (PT), or ...

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Congenital Auditory Deprivation Reduces Synaptic Activity within the Auditory Cortex in a Layer-specific Manner

Cited by 169 publications

References 84 publications

Current focusing and steering: Modeling, physiology, and psychophysics

Current focusing and steering: Modeling, physiology, and psychophysics

Speech perception skills of deaf infants following cochlear implantation: a first report

A morphometric analysis of auditory brain regions in congenitally deaf adults

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