Neonatal Cochlear Hearing Loss Results in Developmental Abnormalities of the Central Auditory Pathways

Harrison, Robert V.; Stanton, Susan G.; Ibrahim, Danyal; Nagasawa, Akira; Mount, Richard J.

doi:10.3109/00016489309135812

Cited by 58 publications

(41 citation statements)

References 18 publications

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“…It is well established that the auditory cortex -like the visual, the somatosensory and the motor cortex -exhibits a remarkable plasticity. Microelectrode studies in different laboratory animals have shown that several months after a partial cochlear lesion the deprived area of the contralateral primary auditory cortex (A1) has undergone an extensive reorganization [Robertson and Irvine, 1989;Harrison et al, 1991Harrison et al, , 1993bRajan et al, 1993;Schwaber et al, 1993;Rajan and Irvine, 1998]. In the case of unilateral cochlear lesions the contralateral A1 was altered so that the A1 region in which frequencies with lesion-induced elevations in cochlear neural sensitivity would have been represented was occupied by an enlarged representation of lesion-edge frequencies (i.e., frequencies adjacent to those with elevated cochlear neural sensitivity).…”

Section: Discussionmentioning

confidence: 99%

Tinnitus and Event-Related Activity of the Auditory Cortex

Hoke

Mühlnickel²,

Roß³

et al. 1998

Audiol Neurotol

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A neuromagnetic study in tinnitus patients and normal-hearing controls was performed with a modified contingent negative variation (CNV) paradigm. While the warning stimulus S1 was a tone burst at an intensity well above threshold, the imperative stimulus S2 was presented at a near threshold intensity because, in the majority of cases, the perceived loudness of tinnitus is very close to the threshold for a pure tone of the same frequency. Subjects had to respond to S2 by pressing a button until its offset was detected. In this case, instead of the usual sudden cut-off of the CNV after the perception of S2, a slow negative deflection develops, the post-imperative negative variation (PINV). Its initial portion probably indicates the development of a second initial CNV because the subject had to attend also to the offset of S2. The neuromagnetic data were analysed both in the time domain and in the frequency domain (short-time spectral analysis of the classical EEG bands). The time domain waveform as well as the spectrotemporal patterns of the MEG bands exhibited deviations from the normal pattern in several tinnitus subgroups, depending on the characteristics of tinnitus (tonal vs. noisiform, monaural vs. binaural) and on the stimulation conditions (tinnitus side vs. non-tinnitus side).

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Section: Discussionmentioning

confidence: 99%

Tinnitus and Event-Related Activity of the Auditory Cortex

Hoke

Mühlnickel²,

Roß³

et al. 1998

Audiol Neurotol

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“…This functional development is substantially influenced by the structure of environmental acoustic inputs in early life, especially within a critical-period time window when the system is most susceptible to alteration by environmental auditory inputs (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13). Introduction of synchronous inputs into the auditory pathway achieved by exposing rat pups to pulsed noise during this time window, for example, results in a disrupted tonotopicity and broader-than-normal frequency tuning curves in the primary auditory cortex (A1).…”

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confidence: 99%

Intensive training in adults refines A1 representations degraded in an early postnatal critical period

Zhou

Merzenich

2007

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

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The spectral, temporal, and intensive selectivity of neurons in the adult primary auditory cortex (A1) is easily degraded in early postnatal life by raising rat pups in the presence of pulsed noise. The nonselective frequency tuning recorded in these rats substantially endures into adulthood. Here we demonstrate that perceptual training applied in these developmentally degraded postcritical-period rats results in the recovery of normal representational fidelity. By using a modified go/no-go training strategy, structured noise-reared rats were trained to identify target auditory stimuli of specific frequency from a set of distractors varying in frequency. Target stimuli changed daily on a random schedule. Consistent with earlier findings, structured noise exposure within the critical period resulted in disrupted tonotopicity within A1 and in degraded frequency-response selectivity for A1 neurons. Tonotopicity and frequency-response selectivity were normalized by perceptual training. Changes induced by training endured without loss for at least 2 months after training cessation. The results further demonstrate the potential utility of perceptual learning as a strategy for normalizing deteriorated auditory representations in older (postcritical-period) children and adults.adult plasticity ͉ cortical plasticity ͉ perceptual training ͉ primary auditory cortex ͉ tonotopic organization

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“…A uditory experience plays an important role in the development of the primary auditory cortex (A1) (1)(2)(3)(4)(5)(6)(7)(8)(9)(10). Exposure of kittens or rat pups to a modulated tonal stimuli during an early postnatal period resulted in an expansion of the representation of the exposed sound frequency in A1 (2,7).…”

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Specialization of primary auditory cortex processing by sound exposure in the “critical period”

Nakahara

Zhang

Merzenich

2004

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

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Environmental acoustic exposure to a complex tone sequence within the critical period in infant rats resulted in the emergence of large-scale, selective changes that radically altered primary auditory cortex (A1) organization. In the sound exposure-revised A1, responses were segregated into two explicit zones representing spectrally and temporally separated lower and higher frequency tone sequence progressions. Cortical neurons between these two A1 zones were poorly driven by sound stimuli. Stimulus sequence-specific (''combination-selective'') responses emerged in the A1 of exposed rats. These selective representational changes induced in the critical period persisted into adulthood. These results show that the temporal order and pace of early, repetitive postnatal auditory inputs strongly affect the emergent and enduring functional organization of A1.A uditory experience plays an important role in the development of the primary auditory cortex (A1) (1-10). Exposure of kittens or rat pups to a modulated tonal stimuli during an early postnatal period resulted in an expansion of the representation of the exposed sound frequency in A1 (2, 7). Synchronous electrical stimulation of a cochlear implant in congenitally deaf cats led to larger cortical regions producing middle-latency evoked responses (11). The formation of an orderly, continuous sound frequency (''tonotopic'') representation and a postnatal sharpening of tonal receptive fields in the rat A1 appeared to require exposure to normally variable auditory inputs during the ''critical period'' (ref. 1, but also see ref. 12 for a difference in cats). However, it remains unclear how the cortical representations of the dynamic aspects of complex sound are specifically shaped by the spectro-temporal patterns of auditory inputs during development. These studies were designed to initiate our attack on this important issue.In this initial study, we exposed rat pups through a critical period epoch extending from postnatal day (P) 9 (before hearing is first functional, at ϷP12) to P30 (when the critical period is drawing to a close) to a tone sequence with two specific spectro-temporal patterns. The frequency representation of A1 was radically revised by the exposure to this complex acoustic stimulus. Cortical neurons developed a preference for the temporal sequences of sound that the infant rat was exposed to. Induced changes endured into adulthood. These results underscore the specific instructive role of early auditory experience in sculpting the specific circuits of the auditory system to selectively and enduringly represent inputs that are present in the criticalperiod acoustic environment. MethodsEarly Exposure of Rat Pups. All of the experimental procedures applied in this study were approved by the University of California San Francisco animal research committee. Litters of nine to twelve 9-day-old female rats (Sprague-Dawley) were placed with their mothers in a calibrated, sound-shielded test chamber from P9 to P30 in the presence of auditory stimulation consi...

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Neonatal Cochlear Hearing Loss Results in Developmental Abnormalities of the Central Auditory Pathways

Cited by 58 publications

References 18 publications

Tinnitus and Event-Related Activity of the Auditory Cortex

Tinnitus and Event-Related Activity of the Auditory Cortex

Intensive training in adults refines A1 representations degraded in an early postnatal critical period

Specialization of primary auditory cortex processing by sound exposure in the “critical period”

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