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PubMed2001

Brainstem auditory regions in mice: expression of nociceptin/orphanin FQ precursor mRNA in select neurons.

Nociceptin peptide-receptor system is known to be essential for the regulation of hearing ability. The mRNA for nociceptin precursor protein is highly expressed in the brainstem. We explored a detailed hybridohistochemical expression pattern of the nociceptin precursor mRNA in the mouse brainstem, and identified positive cells in several auditory brainstem nuclei. Positive cells were seen in the dorsal and ventral nuclei of the lateral lemniscus, the rostral periolivary region, the lateroventral and medioventral periolivary nuclei, the dorsal periolivary region, the superior paraolivary nucleus, and the external cortex and dorsal cortex of the inferior colliculus. Of these, the medioventral and lateroventral periolivary nuclei, the major sites of origin of olivocochlear bundle, were most populated by positive cells.

Animals↗
PubMed2002

Plasticity and corticofugal modulation for hearing in adult animals.

The descending (corticofugal) auditory system adjusts and improves auditory signal processing in the subcortical auditory nuclei. The auditory cortex and corticofugal system evoke small, short-term changes of the subcortical auditory nuclei in response to a sound repetitively delivered to an animal. These changes are specific to the parameters characterizing the sound. When the sound becomes significant to the animal through conditioning (associative learning), the changes are augmented and the cortical changes become long-term. There are two types of reorganizations: expanded reorganization resulting from centripetal shifts in tuning curves of neurons toward the values of the parameters characterizing a sound and compressed reorganization resulting from centrifugal shifts in tuning curves of neurons away from these values. The two types of reorganizations are based on a single mechanism consisting of two components: facilitation and inhibition.

Animals↗
PubMed1980

Acoustic responses after total destruction of the cochlear receptor: brainstem and auditory cortex.

Acoustically evoked neural activity has been recorded from the brainstem and auditory cortex of guinea pigs after complete destruction of the organ of Corti by the aminoglycosidic antibiotic amikacin. These responses to sound differ in important respects from the evoked potentials normally recorded from the auditory pathways. At the brainstem level they resemble the potentials reported by others after stimulation of the vestibular nerve.

Acoustic Stimulation↗
PubMed1994

Effect of aminophylline on brain stem auditory evoked potentials in preterm infants.

To determine the neurophysiological effects of aminophylline on apnoea of prematurity, the brain stem auditory evoked potentials (BAEPs) of 30 apnoeic infants and 34 age matched controls were evaluated and compared. After six days of treatment with aminophylline, the brain stem conduction time (interpeak latency of I-V) in apnoeic infants decreased compared with controls of a similar postconceptional age. The mean latencies of the peaks and interpeaks of all waves except wave I were significantly lower in the apnoeic infants after than before receiving aminophylline. No significant differences were found in the latencies of BAEPs between the apnoeic infants who responded and those who did not respond to aminophylline treatment, however. These results suggest that aminophylline may enhance conduction along central auditory pathways and stimulate the regulatory effect on the respiratory centre of the brain stem.

Aminophylline↗
PubMed1989

Evoked potentials suggest cranial nerves and CNS involvement in chronic relapsing polyradiculoneuropathy.

Brainstem auditory and visual potentials were recorded from 6 patients with chronic idiopathic polyradiculoneuropathy. Evoked potentials were either completely absent or their latency was prolonged suggesting slow conduction in visual or auditory pathways. The results of our study provide further evidence suggesting subclinical involvement of cranial nerves and central nervous system sensory pathways in chronic inflammatory demyelinating polyradiculoneuropathy.

Adult↗
PubMed2006

Computational inference of neural information flow networks.

Determining how information flows along anatomical brain pathways is a fundamental requirement for understanding how animals perceive their environments, learn, and behave. Attempts to reveal such neural information flow have been made using linear computational methods, but neural interactions are known to be nonlinear. Here, we demonstrate that a dynamic Bayesian network (DBN) inference algorithm we originally developed to infer nonlinear transcriptional regulatory networks from gene expression data collected with microarrays is also successful at inferring nonlinear neural information flow networks from electrophysiology data collected with microelectrode arrays. The inferred networks we recover from the songbird auditory pathway are correctly restricted to a subset of known anatomical paths, are consistent with timing of the system, and reveal both the importance of reciprocal feedback in auditory processing and greater information flow to higher-order auditory areas when birds hear natural as opposed to synthetic sounds. A linear method applied to the same data incorrectly produces networks with information flow to non-neural tissue and over paths known not to exist. To our knowledge, this study represents the first biologically validated demonstration of an algorithm to successfully infer neural information flow networks.

Action Potentials↗
PubMed2005

Spatiotemporal properties of the BOLD response in the songbirds' auditory circuit during a variety of listening tasks.

Auditory fMRI in humans has recently received increasing attention from cognitive neuroscientists as a tool to understand mental processing of learned acoustic sequences and analyzing speech recognition and development of musical skills. The present study introduces this tool in a well-documented animal model for vocal learning, the songbird, and provides fundamental insight in the main technical issues associated with auditory fMRI in these songbirds. Stimulation protocols with various listening tasks lead to appropriate activation of successive relays in the songbirds' auditory pathway. The elicited BOLD response is also region and stimulus specific, and its temporal aspects provide accurate measures of the changes in brain physiology induced by the acoustic stimuli. Extensive repetition of an identical stimulus does not lead to habituation of the response in the primary or secondary telencephalic auditory regions of anesthetized subjects. The BOLD signal intensity changes during a stimulation and subsequent rest period have a very specific time course which shows a remarkable resemblance to auditory evoked BOLD responses commonly observed in human subjects. This observation indicates that auditory fMRI in the songbird may establish a link between auditory related neuro-imaging studies done in humans and the large body of neuro-ethological research on song learning and neuro-plasticity performed in songbirds.

Acoustic Stimulation↗
PubMed1989

Middle-latency responses. I. Electrical and acoustic excitation.

The electrically evoked auditory brain-stem response has been used in the past to assess auditory system function with regard to cochlear prosthesis application. The brief latency of the response makes it susceptible to electrical artifact contamination, and waveform identification is often difficult. As a possible alternative for a noninvasive measure of system excitability, the middle-latency response (MLR), elicited by electrical stimulation, was investigated. Middle-latency responses were recorded in response to acoustic and round-window electrical stimulation in albino guinea pigs. Acoustic and electrically evoked MLR waveforms were similar, as were their respective latency/intensity functions. Amplitude/intensity functions for the electric MLR showed greater variability than acoustically evoked MLR functions. The electric MLR is readily evoked and relatively insensitive to electrical artifact in the guinea pig. It is potentially a useful tool in assessing the integrity of auditory pathways and consequently in the development of diagnostic tests for cochlear implant candidates.

Acoustic Stimulation↗
PubMed1989

Visual and brain stem auditory evoked responses in Wilson's disease.

Sensory evoked potentials were studied in 15 patients with Wilson's disease. Thirteen patients were investigated with pattern reversal visual stimulation. A prolonged P 100 latency of the VEP was present in 7 patients. Brain stem auditory responses were evoked in 12 patients. Prolongation of III-V and I-V interpeak latency was found in 8 patients. The evoked potential studies demonstrated subclinical disturbances in optic and caudal brainstem auditory pathways. Further studies are in progress to evaluate the role of these techniques in monitoring the therapy of newly diagnosed cases.

Adolescent↗
PubMed2003

Audiologic presentation of cerebellopontine angle cholesteatoma.

OBJECTIVE: The aim of this study was to examine the audiologic presentation of patients with cerebellopontine angle (CPA) cholesteatoma. DESIGN: Retrospective case review. SETTING: Neuro-otologic tertiary referral centre. METHODS: The study population consisted of 11 patients with CPA cholesteatomas. The patients underwent a standard audiologic investigation in the preoperative setting, which consisted of pure-tone audiometry, speech audiometry, and auditory brainstem response (ABR). MAIN OUTCOME MEASURES: The audiologic parameters that were analyzed were the pure-tone threshold, pure-tone average (PTA), and speech discrimination scores (SDSs). The morphology and latency of the ABR were evaluated. In addition, the clinical and radiologic presentations of the lesions were reviewed. RESULTS: The mean PTA in the diseased ear was 22.6 dB HL (SD 18.2), whereas in the contralateral ear, it was 19.1 dB HL (SD 19.6). In 4 patients, the hearing loss was asymmetric, with the diseased ear being the worse ear. The mean SDS was 82.28% in the affected ear and 95.28% in the contralateral ear. ABR was abnormal in 9 of 10 cases (90%), with only the affected ear being abnormal in 4 cases. In the other 5 cases, the ABR was bilaterally abnormal. CONCLUSIONS: CPA cholesteatomas are very slow-growing lesions that involve the eighth cranial nerve. The paucity and insidious onset of symptoms mean that the diagnosis is often late, permitting the lesions to reach impressive dimensions at the time of diagnosis. Although magnetic resonance imaging represents the gold standard in the diagnosis of these lesions, ABR proved to be of value in the assessment of the auditory pathway, especially in those patients referred with a vague symptomatology and with normal hearing.

Adult↗
PubMed1988

[Electrophysiologic studies of hearing: current methods in clinical and occupational audiology. I. Brain stem evoked response audiometry (ABR)].

Electrophysiological methods of auditory assessment called evoked responses are an exciting new development with broad implications in the fields of otology, audiology and neurology. At the present time they are the best objective non-invasive audiometric tests (versus subjective psychoacoustic examinations) for predicting hearing thresholds in infants and uncooperative patients. Basic concepts of electric response audiometry, most important auditory evoked potentials, their probable sites of generation and classification according to latency i.e. elapsed time between stimulus and response are reviewed. Instrumentation, procedure and technical considerations in recording the brain-stem evoked response audiometry (ABR), the most popular recent method for evoked potentials testing are described. Special attention is focused on measurement, identification and interpretation of brainstem responses and their major clinical uses, namely threshold testing of infants, young children and malingerers, diagnosis of acoustic tumors and neurological evaluation of brainstem lesions. Finally, the first own experience with a new employed in our laboratory the evoked potentials system Amplaid MK 10 for clinical testing of auditory pathways are presented and illustrated by some examples of application of brainstem audiometry in diagnosis of occupational noise-induced hearing loss.

Adult↗
PubMed1997

Hearing threshold assessment with auditory brainstem response (ABR) and ElectroCochleoGraphy (ECochG) in uncooperative children.

Two-hundred-and-sixty uncooperative children (442 ears) performed auditory brainstem response (ABR) and Electrocochleography (ECochG) in the same diagnostic session under general anaesthesia, and the results obtained with the two different methods were compared. A difference > or = 20 dB between the two methods was found in 134 ears (30.3%). The presence of middle ear effusion and symptoms of a possible central nervous system pathology were considered in order to verify the evidence of a correlation between the difference in ABR-ECochG results and these clinical parameters. The presence of middle ear effusion was not significantly correlated with differences > or = 20 dB (p = 0.1347). On the contrary, the presence of symptoms indicative of a possible central nervous system (CNS) involvement was significantly correlated with differences > or = 20 dB (p = 0.0000). ABR has to be considered the first choice in hearing assessment strategy, either for screening or diagnosis. However, the diagnosis of hearing loss only on the basis of the presence or absence of wave V requires some care in case of suspected central auditory pathway lesions. In these cases, ECochG may be the only reliable diagnostic tool for hearing assessment in uncooperative subjects.

Adolescent↗
PubMed2004

[Hearing aids in the elderly. Why is the accommodation so difficult?].

UNLABELLED: PRELIMINARY REMARKS: The acceptance of hearing-aids by elderly people is generally poor. Hearing loss on the other hand increases with age, and the ability to communicate,especially in random noise, diminishes. PATIENTS AND METHODS: Audiometric data on 331 individuals older than 60 years were collected. Sixty people between 15 and 30 and 86 people between 31 and 60 years acted as controls. Tympanograms, hearing thresholds, speech audiometry and dichotic hearing as well as binaural masking level differences and otoacustic emissions for eight frequencies were measured. Hearing aid status was also determined. RESULTS: Our data show more hearing deficits at low frequencies as indicated in the literature. Presbycusis is present solely in the internal ear in 11.5-27.7%, in central hearing structures in 3.8-21.4%, but mainly in all parts of the auditory pathway 50.9-84.6% of cases. Only 15.3% of patients needing hearing aids were actually provided with them. CONCLUSION: Hearing decreases with age but some older people have completely normal hearing. Therefore, a physiological presbycusis does not exist. There are deficits in the inner ear as well as in the central auditory structures which should be determined by audiometric diagnosis. Hearing aid supply should be carefully regulated and audiotherapy carried out.

Adolescent↗
PubMed1994

Auditory cortical responses in humans with congenital unilateral conductive hearing loss.

We recorded auditory evoked magnetic fields from 6 patients with congenital unilateral conductive hearing disorder with a 122-channel whole-head neuromagnetometer. The stimuli were 50-ms 1-kHz tones delivered to the better ear at interstimulus intervals (ISIs) of 2 and 8 s at two different intensities (50 and 70 dB HL). As in normal-hearing subjects, the amplitudes of N100m, the 100-ms response, were larger in 5 patients and the latencies were shorter in 3 patients over the hemisphere contralateral to stimulation. However, in one patient N100m peaked already at 61 ms over the contralateral hemisphere and amplitudes were larger over the ipsilateral hemisphere, possibly reflecting reorganization of the auditory pathways. In 3 patients the latencies were shorter over the ipsilateral hemisphere. The effects of ISI and intensity were similar over both hemispheres and did not differ from those in controls. It seems that congenital unilateral conductive hearing loss does not necessarily lead to any gross disturbances in the human auditory cortex.

Acoustic Stimulation↗
PubMed2000

Olivocochlear neurons sending axon collaterals into the ventral cochlear nucleus of the rat.

The olivocochlear projection constitutes the last stage of the descending auditory system in the mammalian brain. Its neurons reside in the superior olivary complex (SOC) and project to the inner and outer hair cell receptors in the cochlea. Olivocochlear neurons were also reported to send axon collaterals into the cochlear nucleus, but controversies about their number and about species differences persist. By injecting the fluorescent retrograde axonal tracers diamidino yellow and fast blue into the cochlea and the ventral cochlear nucleus (VCN), we studied the distribution and number of olivocochlear neurons with and without axon collaterals into the VCN of the rat. We found that olivocochlear neurons residing in the lateral superior olive (LSO), the intrinsic lateral olivocochlear cells (intrinsic LOCs), do not send axon collaterals into the VCN. By contrast, a majority, and possibly all, olivocochlear neurons residing in the ventral nucleus of the trapezoid body (VNTB), the medial olivocochlear cells (MOCs), do have such axon collaterals. These cells may thus affect processing in the ascending auditory pathway at the level of the receptors and concurrently at the level of the secondary sensory neurons in the cochlear nucleus. Belonging to the lateral olivocochlear system, shell neurons reside around the LSO and form a third group of olivocochlear cells (shell LOCs). Like intrinsic LOCs, they innervate the inner hair cells, but like MOCs they do, by means of axon collaterals, project into the VCN. These findings have implications for understanding both auditory signal processing and the plasticity responses that occur following loss of cochlear function.

Animals↗
PubMed1991

Generator study of brainstem auditory evoked potentials by a radiofrequency lesion method in rats.

The generators of brainstem auditory evoked potentials (BAEPs) in rats were investigated experimentally. Discrete lesions of the brainstem auditory pathway were made unilaterally using a stereotaxic radiofrequency coagulation method, and the BAEPs were recorded before and after the lesions to observe the alterations. The waves of the BAEPs were affected by the lesions as follows: (1) all of the BAEP waves were attenuated or eliminated by a lesion of the auditory nerve; (2) wave II was abolished or attenuated in amplitude following a lesion of the cochlear nucleus; (3) marked reduction or abolition of wave III occurred with some effect on waves IV and V following lesions of the superior olivary complex; (4) the following trough in the wave III was significantly attenuated by lesions of the lateral lemniscus that were associated with inconsistent changes in waves IV and V; (5) no waves were affected significantly by a lesion of the inferior colliculus. The method of radiofrequency lesion using stereotaxic localization proved to be a simpler and more rapid procedure for determining the generators of BAEPs in animals than other surgical lesion methods.

Animals↗
PubMed1985

Auditory brainstem evoked potentials in blast injury.

Blast injury typically consists of a mixed conductive and sensorineural hearing loss. The sensorineural component includes temporary as well as permanent threshold elevations. Auditory brainstem evoked potentials (ABEP) are sensitive to functional changes in various levels along the auditory pathway. ABEP were recorded from 37 survivors of blasts and latency measures were correlated with clinical findings. Prolongation of peak latencies was correlated with the conductive component of blast-induced hearing loss, as well as with the TTS component of the sensorineural impairment. No central effects of blast on the auditory system were detected. In addition to their objectivity, ABEP hold the promise of differentiating between the permanent and temporary effects of blast on hearing.

Adult↗
PubMed2005

[Auditory brain stem response assessment in Ramsay Hunt syndrome].

OBJECTIVE: To discuss the changes of the auditory brain stem response in patients with Ramsay Hunt syndrome. METHOD: Thirty-six patients of Ramsay Hunt syndrome,who have only unilateral involvement with contralateral good ear, were studied with pure tone test and auditory brain stem response. The latencies of peaks I, III and V and interpeak latencies of I-III, I-V and III-V in bilateral ears were analyzed by SPSS 10.0 for windows. RESULT: Compared to the controlateral, the affected ears were significantly increased in latencies of II, V and interpeak latencies of I-III, I-V ( P < 0.05). CONCLUSION: The audiological data suggested that cochlear or retrocochlear involvement or involvement at more than one site along the auditory pathway existed in Ramsay Hunt syndrome, but pure cochlear hearing loss is not common.

Adolescent↗