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PubMed1978

Peripheral auditory processing in normal and abnormal ears: physiological considerations for attempts to compensate for auditory deficits by acoustic and electrical prostheses.

The processing of complex acoustic signals, such as speech, by the normal peripheral auditory system is described in terms of the properties of individual cochlear nerve fibres and the effects of lateral inhibition in the cochlear nucleus. The implications of the peripheral filtering of signals is indicated in psychophysical terms. In cochlear pathology, these filtering characteristics deteriorate, and the implications arising from the consequent deterioration in auditory frequency selectivity are outlined for the coding of loudness and for the analysis of speech. These considerations suggest theoretically ideal methods of compensation for recruitment by multichannel instantaneous compression, and for deterioration in format analysis by dichotic frequency partition. Finally, the implications for a minimal design for artificial electrical multi-electrode array stimulation of the cochlea in order to impart speech information to the profoundly deaf, are explored. Single wire stimulation, on the other hand, should be able to impart useful prosodic and minimal speech feature information to aid in lip reading and in the acquisition of speech.

Animals↗
PubMed1994

Involvement of auditory cortical and hippocampal neurons in auditory working memory and reference memory in the rat.

The goal of the present study was to see whether one neuron is involved exclusively in one type of memory or in different types of memory. Single-unit activity was recorded from rat hippocampal CA1, CA3, dentate gyrus, and auditory cortex (AC) during performances of auditory working memory (WM) and reference memory (RM) tasks. Both the memory tasks employed identical apparatus and stimuli and differed only in the type of memory required for correct performance. Around 10% and 43% of the units from the four brain regions showed sensory correlates (differences in activity due to the type of sensory stimulus) only in the WM or RM task, respectively. Only the AC had units showing different kinds of sensory correlates between the WM and RM tasks. About 30% of the units from the four regions had sensory-retention correlates (sustained differential activity during the delay) only in the RM task, whereas the AC had units with sensory-retention correlates only in the WM task or in both the WM and RM tasks. Approximately 35% of the units from the hippocampal regions showed motor correlates (increments of activity immediately prior to responses) only in the WM task. Another 30% of the hippocampal units showed such correlates both in the WM and RM tasks. About 22% of the hippocampal CA1 and CA3 units showed comparison-motor correlates (increases of activity prior to correct responses) only in the WM task. These results indicate that some neurons are involved solely in WM or RM, whereas other neurons are involved in both WM and RM. The results also suggest that more neurons are involved in sensory and retention processing for RM than for WM, and that the AC alone has flexible neurons involved in the processes for both types of memory. More hippocampal neurons are involved in the motor and comparison processes for WM than for RM.

Acoustic Stimulation↗
PubMed1986

Representation of amplitude modulation in the auditory cortex of the cat. I. The anterior auditory field (AAF).

The ability of cortical neurons to follow amplitude modulation (AM) of tones was examined in the anterior auditory cortical field (AAF) of anesthetized cats using multiple-unit recording techniques. Sinusoidal and rectangular modulations (100%) of a monaural carrier tone at the characteristic frequency of each location were presented to study the degree of response synchronization and changes in firing rate as a function of the modulation frequency. All investigated locations were tuned to a 'best modulation frequency' (BMF) as determined by synchronization measures. Almost all locations (94%) were tuned to a BMF as determined by spike rate. Maximal binaural-interaction strength was observed for modulation frequencies close to the BMF of neurons. For sinusoidal AM, a correlation (r = 0.63, P less than 0.01) between BMF and CF of neurons in AAF could be demonstrated for the synchronization of the response.

Acoustic Stimulation↗
PubMed2002

Central auditory onset responses, and temporal asymmetries in auditory perception.

Historically, central auditory responses have been studied for their sensitivity to various parameters of tone and noise burst stimulation, with response rate plotted as a function of the stimulus variable. The responses themselves are often quite brief, and locked in time to stimulus onset. In the stimulus amplitude domain, it has recently become clear that these responses are actually driven by properties of the stimulus' onset transient, and this has had important implications for how we interpret responses to manipulations of tone (or noise) burst plateau level. That finding was important in its own right, but a more general scrutiny of the available neurophysiological and psychophysical evidence reveals that there is a significant asymmetry in the neurophysiological and perceptual processing of stimulus onsets and offsets: sound onsets have a more elaborate neurophysiological representation, and receive a greater perceptual weighting. Hypotheses about origins of the asymmetries, derived independently from psychophysics and from neurophysiology, have in common a response threshold mechanism which adaptively tracks the ongoing level of stimulation.

Acoustic Stimulation↗
PubMed1985

Tuning of the auditory brainstem OFF responses is complementary to tuning of the auditory brainstem ON response.

Continuous masking studies show a complementary pattern of effects on the auditory brainstem responses (ABRs) which are generated by the onset and by the offset of a midfrequency tone. The masking profiles of the two responses are almost opposite with a probe stimulus frequency of 32 kHz (16-32 kHz is the midfrequency region for the CBA/J mouse). The Offset and Onset ABR tuning curves (TCs) also reveal very different properties at the midfrequencies of 16, 20, 24 and 32 kHz. The Offset TC is exquisitely sensitive to masking by very low intensity stimuli at a narrow range of frequencies which are lower than the probe stimulus frequency. Continuous masking produces a well-tuned low frequency tip to the Offset TC. For Offset TCs generated in response to midfrequency tones, the Q+10 dB of this tip averages 8.3. Masking at this low frequency tip of the Offset TC has no observable effect on the Onset ABR. The Offset ABR is also sensitive to masking by a narrow range of frequencies which are higher than the probe stimulus frequency. This occurs at an intensity which also has no observable effect on the Onset ABR. The Q+10 dB of this high frequency tip averages 9.2. The average frequencies where these Offset TC tips occur fit the cubic difference formula (2f1-f2), which describes a distortion product of two-tone suppression. At low probe stimulus frequencies, there is only a high frequency Offset TC tip; at high stimulus frequencies, only a low frequency tip. The high frequency tip has a higher threshold and appears more susceptible to metabolic disturbance. The Offset ABR TC also has a peak which corresponds to the probe stimulus frequency. Continuous masking with the stimulus frequency produces nonmonotonic enhancement of the Offset ABR, while it simultaneously reduces the magnitude of the Onset ABR. The tuning of this Offset TC peak (measured as Q-10 dB) is almost always much sharper than the corresponding Onset TC tip in the same mouse. These values for midfrequency stimuli average 6.2 for the Onset, and 13.6 for the Offset TCs. This fine tuning of the Offset TC at the probe stimulus frequency occurs at SPLs from 50 to more than 90 dB.

Animals↗
PubMed2006

Temporal resolution properties of human auditory cortex: reflections in the neuromagnetic auditory evoked M100 component.

UNLABELLED: Previous work has provided evidence for a brief, finite ( approximately 35 ms) temporal window of integration (TWI) in M100 formation, during which stimulus attributes are accumulated in processes leading to the M100 peak. Here, we investigate resolution within the TWI by recording responses to tones containing silent gaps (0-20 ms). Gaps were inserted in 1 kHz tones in 2 conditions: +10 ms post-onset (10 ms masker) wherein the masker and gap of longest duration (20 ms) were contained within the initial 35 ms of the stimulus and +40 ms (40 ms masker) wherein all gaps were inserted +40 ms post-onset. Tones were presented binaurally and responses sampled from both hemispheres in 12 adults using a twin 37-channel biomagnetometer (MAGNES-II, BTi, San Diego, CA). Results--10 ms masker: M100 latency was prolonged and amplitude decreased as a function of gap duration, even with the shortest duration (2 ms) gap, indicating that integrative processes underlying M100 formation are sensitive to fine-grained discontinuities within a brief, finite TWI. Results--40 ms masker: M100 latency and amplitude were unaffected by gaps inserted at +40 ms, providing further evidence for an M100 TWI of <40 ms. CONCLUSION: within a brief integrative window in M100 formation, population-level responses are sensitive to discontinuities in sounds on a scale corresponding to psychophysical detection thresholds and minimum detectable gap thresholds in single unit recordings. Cumulatively, results provide evidence that M100 resolution for brief fluctuations in sounds reflects temporal acuity properties that are both intrinsic to the auditory system and critical to the accurate perception of speech.

Acoustic Stimulation↗
PubMed2005

Three young adult patients with Pelizaeus-Merzbacher disease who showed only waves I and II in auditory brainstem responses but had good auditory perception.

Three young adult males with Pelizaeus-Merzbacher disease have been followed up since childhood. This disease is thought to be a dysmyelinating disorder of the brain during the prenatal period caused by gene mutations. The patients manifested horizontal nystagmus and severe rigidity of the extremities. Although the patients showed only waves I and II in auditory brainstem responses, they had relatively good hearing ability at approximately equal to dB. They could not speak words at all but could hear well and enjoy listening to conversation and music. One of them had a normal hearing threshold in pure-tone audiometry and a normal speech discrimination rate in speech audiometry. This can be explained by a nerve conduction blockade through dysmyelinated axons or the desynchronization of neurons and nerves responsible for the waves following waves I and II. At present, all three patients are living with their families. We report their present hearing, speech and language abilities.

Adult↗
PubMed1995

Neural correlates of gap detection and auditory fusion in cat auditory cortex.

Responses were recorded from 130 single neurones in the primary auditory cortex of 12 ketamine-anaesthetized cats in response to double-click stimuli, to a /ba/-/pa/ phoneme continuum and to gaps inserted early (after 5 ms) and late (after 500 ms) in a 1 s duration noiseburst. Stimulus levels were between 45 and 75 dB SPL. Neural detection threshold for the 'late gap' was less than 5 ms. For the double click and 'early gap' stimuli thresholds were between 40 and 50 ms, whereas the phoneme continuum threshold for voice-onset-time (VOT) was between 10 and 25 ms. The 'late gap' and VOT thresholds are similar to psychophysical gap detection and the /ba/-/pa/ categorical perception boundary respectively.

Acoustic Stimulation↗
PubMed2003

[Responses of neurons in the primary auditory cortex of the cat to the auditory motion stimuli with variable interaural delay].

Unit responses in the primary auditory cortex of anesthetized cats to stationary and apparently moving stimuli resulted from a static and dynamically varying interaural delay (ITD) were recorded. The static stimuli consisted of binaurally presented tones and clicks. The dynamic stimuli were produced by in-phase and out-of-phase binaurally presented click trains with time-varying ITD. Sensitivity to ITDs was mostly seen in responses of the neurons with low characteristic frequency (below 2.8 kHz). All cells sampled with static stimuli responded to simulated motion. A motion effect could take the form of a difference in response magnitude depending on the direction of stimulus motion and a shift in the ITD-function opposite the direction of motion. The magnitude of motion effects was influenced by the position of motion trajectory relative to the ITD-function. The greatest motion effect was produced by motion crossing the ITD-function slopes.

Acoustic Stimulation↗
PubMed1995

Central auditory processing: a view from auditory neuroscience.

The purpose of this report is to overview some recent advances in basic science that help us understand the roles of the central auditory nervous system in hearing. Particularly at rostral levels, neural representations of the acoustic signal are shaped by convergent inputs and show some degree of plasticity, even in adults. The fidelity with which brain regions represent a stimulus dimension is heterogeneous, and this has demonstrable implications for the perceptual consequences of damage to those regions. So-called higher-level disorders (e.g., phonologic ones) have become increasingly understandable, largely through work in cognitive neuroscience, which has begun to describe the functional architecture of the processes mediating sound recognition and comprehension.

Animals↗
PubMed2000

[Surgery of the external auditory canal in familial bilateral auditory canal atresia].

BACKGROUND: Inherited isolated bilateral atresia of the external auditory canal is rare. Ear canal surgery procedure is difficult. METHODS: Basing on a case report of a family with inherited isolated bilateral atresia of the external auditory canal in 4 cases the way of preoperative diagnostics including human genetics and our surgical concept is described. RESULTS: Resulting clinical findings showed complete epithelialization of the ear canal and ear drum with slight conductive hearing loss. CONCLUSIONS: Canaloplasty in atresia can be easily and successfully accomplished by our modified technique.

Adolescent↗
PubMed1992

TGF beta 1 expression is initiated in adult auditory neurons by sectioning of the auditory nerve.

Neuronotrophic factors (e.g. basic fibroblast growth factor, bFGF and nerve growth factor, NGF) have been demonstrated to respectively promote survival and neuritogenesis in cultures of dissociated adult rat spiral ganglia. Transforming growth factor beta (TGF beta 1) has been shown to modulate the response of cultured auditory neurons to bFGF through the induction of high affinity receptors for bFGF in the neurons. In this study, we show that TGF beta is expressed in situ by adult auditory neurons in response to traumatic injury (i.e. transection of the eighth cranial nerve). Based on these in vivo results and on the results from our previous in vitro studies, we propose that TFG beta 1 acts as an early autocrine signal involved in the response to injury by neurons of the peripheral auditor system.

Animals↗
PubMed1984

Auditory screening of special care neonates using the auditory response cradle.

The Linco-Bennett auditory response cradle is a microprocessor controlled device for screening the hearing of neonates. A total of 396 neonates admitted to a special care unit were tested on the cradle and later followed up in a comprehensive test programme between the ages of 3 months and 8 months. Altogether 374 (94%) were available for follow up. The use of the cradle resulted in the detection of six neonates with appreciable deafness. One neonate who passed the cradle test has severe bilateral hearing impairment. The false alarm rate for neonates failing two tests on the cradle but having normal hearing at follow up was 4.3%. The auditory response cradle was designed for use in mass screening programmes but testing the hearing of all newborns would require many staff. It is argued that this is unrealistic when resources are scarce, but that neonates in high risk groups should have their hearing screened at birth by an objective test such as this. The cradle has considerable potential but its method of use and the 'decision making' programme could be improved.

Critical Care↗
PubMed2004

Utilization of the auditory consonant trigram test to screen for cognitive impairment in patients with multiple sclerosis: comparison with the paced auditory serial addition test.

Several screening methods have been evaluated, but most of them are insensitive to MS-related cognitive impairment. The Auditory Consonant Trigram (ACT) test, which contains core features required for a working memory task, has been used to test neuro-cognitive function in different samples of patients to examine the status of working memory. The aim of the present study was to investigate the correlation between ACT and the Paced Auditory Serial Addition Test (PASAT), and the usefulness of ACT for evaluating the cognitive impairment in MS in a brief visit A total of 109 consecutive patients with definite MS were included. The patients were administered ACT, PASAT and EDSS. Mean PASAT score and mean ACT score were 46.19 +/- 8.51 and 45.30 +/- 9.07, respectively. Correlations between EDSS and PASAT, and EDSS and ACT were moderately strong. The correlation between ACT and PASAT was very strong (r = 0.831, P < 0.01). The mean time required to perform ACT was significantly shorter than PASAT (7.25 +/- 4.72 and 14.70 +/- 6.97 minutes, respectively). In conclusion, as a relatively brief measure of working memory, ACT was well accepted by MS patients and has a strong correlation with PASAT. Thus, ACT might be used for rapid evaluation of cognitive impairment in patients with multiple sclerosis.

Adult↗
PubMed1981

Reinforcement of vocal correlates of auditory hallucinations by auditory feedback: a case study.

Although auditory hallucinations in schizophrenic patients are usually thought to be private events, several early writers observed vocalizations concurrent with hallucinations. The content of such vocalizations corresponded to what the voices were reported to have said. A schizophrenic patient is described whose whispers were increased to an intelligible level by the use of auditory feedback. This has implications for the self-control of hallucinations, and for neurological theories of verbal hallucinations.

Feedback↗
PubMed2000

First auditory brainstem implantation in Poland: auditory perception results over 12 months.

Auditory brainstem implants (ABIs) are a modern method of treatment of total bilateral deafness in cases of extracochlear origin. In most cases therapy is applied in patients with neurofibromatosis type 2 (NF2). This paper presents the results of surgical treatment and rehabilitation in a 28-year-old woman with bilateral, multiple tumours of the central nervous system causing total deafness. Simultaneous removal of the tumours and implantation of ABI allowed treatment of the potentially lethal pathology and hearing restoration. Improving auditory skills and excellent tests results were noted in the year following implantation.

Adult↗
PubMed2005

Auditory fear conditioning and long-term potentiation in the lateral amygdala require ERK/MAP kinase signaling in the auditory thalamus: a role for presynaptic plasticity in the fear system.

In the present study, we examined the role of the auditory thalamus [medial division of the medial geniculate nucleus and the adjacent posterior intralaminar nucleus (MGm/PIN)] in auditory pavlovian fear conditioning using pharmacological manipulation of intracellular signaling pathways. In the first experiment, rats were given intrathalamic infusions of the MEK (mitogen-activated protein kinase-kinase) inhibitor 1,4-diamino-2,3-dicyano-1,4-bis(o-aminophenylmercapto) butadiene (U0126) before fear conditioning. Findings revealed that long-term memory (assessed at 24 h) was impaired, whereas short-term memory (assessed at 1-3 h) of fear conditioning was intact. In the second experiment, rats received immediate posttraining intrathalamic infusion of U0126, the mRNA synthesis inhibitor 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB), or infusion of the protein synthesis inhibitor anisomycin. Posttraining infusion of either U0126 or DRB significantly impaired long-term retention of fear conditioning, whereas infusion of anisomycin had no effect. In the final experiment, rats received intrathalamic infusion of U0126 before long-term potentiation (LTP)-inducing stimulation of thalamic inputs to the lateral nucleus of the amygdala (LA). Findings revealed that thalamic infusion of U0126 impaired LTP in the LA. Together, these results suggest the possibility that MGm/PIN cells that project to the LA contribute to memory formation via ERK (extracellular signal-regulated kinase)-mediated transcription, but that they do so by promoting protein synthesis-dependent plasticity locally in the LA.

Acoustic Stimulation↗