Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “auditory”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 577 records · Page 32Linked to original sources
PubMedDate not supplied

Locating voices in space: a perceptual model for auditory hallucinations?

INTRODUCTION: Auditory hallucinations are often perceived as being located in external auditory space ("outside the head"), like real auditory perceptions, but in the absence of a speaker or other external stimulus. METHOD: A selective literature review of the spatial phenomenology of auditory hallucinations and the cognitive neuroscience of locating real voices in external space was undertaken. An auditory-perceptual model of external auditory hallucinations was developed in healthy right-handed subjects using functional magnetic resonance imaging and the presentation of speech in virtual acoustic space. RESULTS: Karl Jaspers inextricably linked "reality" and "externality" of auditory hallucinations. Although these two properties do not always occur simultaneously in hallucinating patients, the issue of "externality" is important from both a clinical and neuroscientific perspective. In an auditory-perceptual model of auditory hallucinations, association cortex in the left planum temporale is critically involved in the perception of real voices as located in external space. Right-sided voice stimuli are associated with greater neural response in the dominant (left) auditory cortex than left-sided stimuli. Subjects are better at identifying the spatial location of voices presented on the right than on the left. CONCLUSION: The auditory-perceptual model described helps identify candidate brain systems likely to be involved in the pathogenesis of auditory hallucinations in schizophrenia, and is distinct from other models, which use concepts of "internal monitoring" and "inner speech". Its application, in the cognitive neuroscientific investigation of the phenomenology of auditory hallucinations, may shed further light on the mechanisms underlying this distressing experience.

Journal Article↗
PubMed1999

Responses to auditory stimuli in macaque lateral intraparietal area. II. Behavioral modulation.

The lateral intraparietal area (LIP), a region of posterior parietal cortex, was once thought to be unresponsive to auditory stimulation. However, recent reports have indicated that neurons in area LIP respond to auditory stimuli during an auditory-saccade task. To what extent are auditory responses in area LIP dependent on the performance of an auditory-saccade task? To address this question, recordings were made from 160 LIP neurons in two monkeys while the animals performed auditory and visual memory-saccade and fixation tasks. Responses to auditory stimuli were significantly stronger during the memory-saccade task than during the fixation task, whereas responses to visual stimuli were not. Moreover, neurons responsive to auditory stimuli tended also to be visually responsive and to exhibit delay or saccade activity in the memory-saccade task. These results indicate that, in general, auditory responses in area LIP are modulated by behavioral context, are associated with visual responses, and are predictive of delay or saccade activity. Responses to auditory stimuli in area LIP may therefore be best interpreted as supramodal responses, and similar in nature to the delay activity, rather than as modality-specific sensory responses. The apparent link between auditory activity and oculomotor behavior suggests that the behavioral modulation of responses to auditory stimuli in area LIP reflects the selection of auditory stimuli as targets for eye movements.

Acoustic Stimulation↗
PubMed2004

Thalamic projections to the auditory cortex in the rufous horseshoe bat (Rhinolophus rouxi). II. Dorsal fields.

In this study, we analyzed the thalamic connections to the parietal or dorsal auditory cortical fields of the horseshoe bat, Rhinolophus rouxi. The data of the present study were collected as part of a combined investigation of physiologic properties, neuroarchitecture, and chemoarchitecture as well as connectivity of cortical fields in Rhinolophus, in order to establish a neuroanatomically and functionally coherent view of the auditory cortex. Horseradish peroxidase or wheat-germ-agglutinated horseradish peroxidase deposits were made into cortical fields after mapping response properties. The dorsal fields of the auditory cortex span nearly the entire parietal region and comprise more than half of the non-primary auditory cortex. In contrast to the temporal fields of the auditory cortex, which receive input mainly from the ventral medial geniculate body (or "main sensory nucleus"), the dorsal fields of the auditory cortex receive strong input from the "associated nuclei" of the medial geniculate body, especially from the anterior dorsal nucleus of the medial geniculate body. The anterior dorsal nucleus is as significant for the dorsal fields of the auditory cortex as the ventral nucleus of the medial geniculate body is for the temporal fields of the auditory cortex. Additionally, the multisensory nuclei of the medial geniculate body provide a large share of the total input to the nonprimary fields of the auditory cortex. Comparing the organization of thalamic auditory cortical afferents in Rhinolophus with other species demonstrates the strong organizational similarity of this bat's auditory cortex with that of other mammals, including primates, and provides further evidence that the bat is a relevant and valuable model for studying mammalian auditory function.

Animals↗
PubMed2003

Cochlear implantation in patients with auditory neuropathy of varied etiologies.

OBJECTIVES/HYPOTHESIS: Auditory neuropathy is a relatively recently described pattern of hearing loss characterized by preservation of outer hair cell function despite absent brainstem auditory evoked responses. Intact outer hair cell function is demonstrated by the presence of otoacoustic emissions and/or a measurable cochlear microphonic on electrocochleography, whereas no synchronous neural activity (absent action potentials) is seen on acoustically evoked brainstem auditory evoked response testing. The study reviews the authors' experience with six patients diagnosed with auditory neuropathy, four of whom have undergone cochlear implantation. MATERIALS AND METHODS: A retrospective review of all medical and audiological charts at the University of Virginia Hospitals (Charlottesville, VA) was performed to identify patients who have undergone cochlear implantation or have been diagnosed with auditory neuropathy, or both. RESULTS: Six patients with hearing loss attributable to auditory neuropathy were identified, four of whom have undergone cochlear implantation. Causes varied, including congenital, infectious, and idiopathic origins. Adults demonstrated subjective auditory perception on promontory stimulation, whereas no repeatable brainstem auditory evoked response waveforms could be demonstrated on pediatric promontory stimulation testing. Patients with implants demonstrated implant-evoked brainstem auditory evoked responses and improved audiological performance. CONCLUSIONS: The six cases presented in the study represent varied causes and, probably, varied sites of lesions of auditory neuropathy. Promontory stimulation has been valuable, particularly in adults. Cochlear implantation allows the opportunity to provide a supraphysiological electrical stimulation to the auditory nerve, with the hope of reintroducing synchronous neural activity. Greater confidence and enthusiasm for cochlear implantation in appropriately selected patients with auditory neuropathy are gained through experience with such diverse cases.

Adult↗
PubMed2001

Role of mammalian auditory cortex in the perception of elementary sound properties.

Studies in several mammalian species have demonstrated that bilateral ablations of the auditory cortex have little effect on simple sound intensity and frequency-based behaviors. In the rat, for example, early experiments have shown that auditory ablations result in virtually no effect on the rat's ability to either detect tones or discriminate frequencies. Such lesion experiments, however, typically examine an animal's performance some time after recovery from ablation surgery. As such, they demonstrate that the cortex is not essential for simple auditory behaviors in the long run. Our study further explores the role of cortex in basic auditory perception by examining whether the cortex is normally involved in these behaviors. In these experiments we reversibly inactivated the rat primary auditory cortex (AI) using the GABA agonist muscimol, while the animals performed a simple auditory task. At the same time we monitored the rat's auditory activity by recording auditory evoked potentials (AEP) from the cortical surface. In contrast to lesion studies, the rapid time course of these experimental conditions preclude reorganization of the auditory system that might otherwise compensate for the loss of cortical processing. Soon after bilateral muscimol application to their AI region, our rats exhibited an acute and profound inability to detect tones. After a few hours this state was followed by a gradual recovery of normal hearing, first of tone detection and, much later, of the ability to discriminate frequencies. Surface muscimol application, at the same time, drastically altered the normal rat AEP. Some of the normal AEP components vanished nearly instantaneously to unveil an underlying waveform, whose size was related to the severity of accompanying behavioral deficits. These results strongly suggest that the cortex is directly involved in basic acoustic processing. Along with observations from accompanying multiunit experiments that related the AEP to AI neuronal activity, our results suggest that a critical amount of activity in the auditory cortex is necessary for normal hearing. It is likely that the involvement of the cortex in simple auditory perceptions has hitherto not been clearly understood because of underlying recovery processes that, in the long-term, safeguard fundamental auditory abilities after cortical injury.

Animals↗
PubMed2004

Bigger brains or bigger nuclei? Regulating the size of auditory structures in birds.

Increases in the size of the neuronal structures that mediate specific behaviors are believed to be related to enhanced computational performance. It is not clear, however, what developmental and evolutionary mechanisms mediate these changes, nor whether an increase in the size of a given neuronal population is a general mechanism to achieve enhanced computational ability. We addressed the issue of size by analyzing the variation in the relative number of cells of auditory structures in auditory specialists and generalists. We show that bird species with different auditory specializations exhibit variation in the relative size of their hindbrain auditory nuclei. In the barn owl, an auditory specialist, the hindbrain auditory nuclei involved in the computation of sound location show hyperplasia. This hyperplasia was also found in songbirds, but not in non-auditory specialists. The hyperplasia of auditory nuclei was also not seen in birds with large body weight suggesting that the total number of cells is selected for in auditory specialists. In barn owls, differences observed in the relative size of the auditory nuclei might be attributed to modifications in neurogenesis and cell death. Thus, hyperplasia of circuits used for auditory computation accompanies auditory specialization in different orders of birds.

Animals↗
PubMed2001

A single-band envelope cue as a supplement to speechreading of segmentals: a comparison of auditory versus tactual presentation.

OBJECTIVE: The objective of this study was to compare the effects of a single-band envelope cue as a supplement to speechreading of segmentals and sentences when presented through either the auditory or tactual modality. DESIGN: The supplementary signal, which consisted of a 200-Hz carrier amplitude-modulated by the envelope of an octave band of speech centered at 500 Hz, was presented through a high-performance single-channel vibrator for tactual stimulation or through headphones for auditory stimulation. Normal-hearing subjects were trained and tested on the identification of a set of 16 medial vowels in /b/-V-/d/ context and a set of 24 initial consonants in C-/a/-C context under five conditions: speechreading alone (S), auditory supplement alone (A), tactual supplement alone (T), speechreading combined with the auditory supplement (S+A), and speechreading combined with the tactual supplement (S+T). Performance on various speech features was examined to determine the contribution of different features toward improvements under the aided conditions for each modality. Performance on the combined conditions (S+A and S+T) was compared with predictions generated from a quantitative model of multi-modal performance. To explore the relationship between benefits for segmentals and for connected speech within the same subjects, sentence reception was also examined for the three conditions of S, S+A, and S+T. RESULTS: For segmentals, performance generally followed the pattern of T < A < S < S+T < S+A. Significant improvements to speechreading were observed with both the tactual and auditory supplements for consonants (10 and 23 percentage-point improvements, respectively), but only with the auditory supplement for vowels (a 10 percentage-point improvement). The results of the feature analyses indicated that improvements to speechreading arose primarily from improved performance on the features low and tense for vowels and on the features voicing, nasality, and plosion for consonants. These improvements were greater for auditory relative to tactual presentation. When predicted percent-correct scores for the multi-modal conditions were compared with observed scores, the predicted values always exceeded observed values and the predictions were somewhat more accurate for the S+A than for the S+T conditions. For sentences, significant improvements to speechreading were observed with both the auditory and tactual supplements for high-context materials but again only with the auditory supplement for low-context materials. The tactual supplement provided a relative gain to speechreading of roughly 25% for all materials except low-context sentences (where gain was only 10%), whereas the auditory supplement provided relative gains of roughly 50% (for vowels, consonants, and low-context sentences) to 75% (for high-context sentences). CONCLUSIONS: The envelope cue provides a significant benefit to the speechreading of consonant segments when presented through either the auditory or tactual modality and of vowel segments through audition only. These benefits were found to be related to the reception of the same types of features under both modalities (voicing, manner, and plosion for consonants and low and tense for vowels); however, benefits were larger for auditory compared with tactual presentation. The benefits observed for segmentals appear to carry over into benefits for sentence reception under both modalities.

Adult↗
PubMed2003

Ear of stimulation determines schizophrenia-normal brain activity differences in an auditory paired-stimuli paradigm.

Schizophrenia patients have abnormalities of auditory information processing, theoretically associated with dysfunction of neuronal excitation. Auditory paired-stimuli (S1-S2) paradigms are used to evaluate the nature of these abnormalities. It is unknown whether patients' abnormalities during S1-S2 paradigms are attributable to specific hemispheric differences in cortical processing. The present studies used whole head magnetoencephalography and monaural or binaural versions of the paired-stimuli paradigm to evaluate auditory processing among 38 schizophrenia and 38 normal subjects. The strengths of auditory-evoked brain responses over time were quantified using distributed source reconstructions with L2 minimum norm constraint and realistic head models. For left ear stimuli, schizophrenia and normal groups did not differ on either left or right hemisphere activity over auditory cortex. For right ear and binaural stimuli, schizophrenia patients had less activity over left auditory cortex from 80 to 120 ms post-stimulus but did not differ from normal on activity over right auditory cortex. Additionally, in response to monaural stimulation, schizophrenia patients had significantly less activity than normal over right temporal parietal junction from 60 to 120 ms post-stimulus. These data are consistent with four propositions about schizophrenia: (i). right auditory cortex is functioning normally; (ii). processing of simple auditory stimuli is abnormal in left auditory cortex, probably specifically in supra-granular layers; (iii). auditory localization abilities are deficient; and (iv). auditory cortex abnormalities are not a function of deficient hemispheric communication because they are evident early in processing as long as stimuli are delivered directly to left hemisphere.

Acoustic Stimulation↗
PubMed1986

Unit study of monkey frontal cortex: active localization of auditory and of visual stimuli.

The influence of sound localization behavior on unit activity in the frontal cortex of awake rhesus monkeys was examined by comparing responses under three behavioral conditions: auditory localization, during which a response was required to the location of a sound (broad-band noise) source; auditory detect, during which a response was required to indicate the occurrence of the sound regardless of location; visual localization, during which no sounds were presented and a response was required to the location of a visual stimulus; and nonperform, presentation of auditory stimuli as in the first two conditions, but with the animal sitting passively. Extracellular microelectrode recordings were made in the periarcuate region and dorsal and ventral prefrontal areas near the principal sulcus. Four monkeys were used with a total of 498 cells studied. Of the total population, only five cells were found to have characteristics similar to those of auditory units in the primary auditory cortex and the surrounding belt area. More typically, units were found that had strong short-latency responses specific to the auditory and/or visual localization tasks. These units had no or weak responses when the same sound stimuli were presented in the auditory detect task or when a monkey received the sound stimuli in a nonperforming condition. Two regions were identified, one medial and/or posterior to the arcuate sulcus, in Brodmann's area 6; the second included parts of areas 8 and 9 within the genu of the arcuate sulcus. Units from these regions are referred to, respectively, as the postarcuate and the prearcuate populations. Both populations responded predominantly during active localization behavior. Sixty-two percent of the postarcuate population responded during auditory localization, 32% responded during auditory detect, and only 18% responded to acoustic stimuli presented in the nonperforming condition. In the prearcuate population percentages in these three conditions were 35, 25, and 12%, respectively. For visual localization, 54% in the postarcuate population responded, whereas 42% in the prearcuate responded. Spatial tuning of units during auditory localization was similar to that seen in units of the primary auditory cortex, with the greatest percentages of units responding to stimuli contralateral to the recording site. Similar tuning was observed for the visual localization task as well. Similarities in spatial tuning between the auditory and visual localization conditions were examined to assess the "bimodal" nature of the units.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2002

Auditory-visual interactions subserving goal-directed saccades in a complex scene.

This study addresses the integration of auditory and visual stimuli subserving the generation of saccades in a complex scene. Previous studies have shown that saccadic reaction times (SRTs) to combined auditory-visual stimuli are reduced when compared with SRTs to either stimulus alone. However, these results have been typically obtained with high-intensity stimuli distributed over a limited number of positions in the horizontal plane. It is less clear how auditory-visual interactions influence saccades under more complex but arguably more natural conditions, when low-intensity stimuli are embedded in complex backgrounds and distributed throughout two-dimensional (2-D) space. To study this problem, human subjects made saccades to visual-only (V-saccades), auditory-only (A-saccades), or spatially coincident auditory-visual (AV-saccades) targets. In each trial, the low-intensity target was embedded within a complex auditory-visual background, and subjects were allowed over 3 s to search for and foveate the target at 1 of 24 possible locations within the 2-D oculomotor range. We varied systematically the onset times of the targets and the intensity of the auditory target relative to background [i.e., the signal-to-noise (S/N) ratio] to examine their effects on both SRT and saccadic accuracy. Subjects were often able to localize the target within one or two saccades, but in about 15% of the trials they generated scanning patterns that consisted of many saccades. The present study reports only the SRT and accuracy of the first saccade in each trial. In all subjects, A-saccades had shorter SRTs than V-saccades, but were more inaccurate than V-saccades when generated to auditory targets presented at low S/N ratios. AV-saccades were at least as accurate as V-saccades but were generated at SRTs typical of A-saccades. The properties of AV-saccades depended systematically on both stimulus timing and S/N ratio of the auditory target. Compared with unimodal A- and V-saccades, the improvements in SRT and accuracy of AV-saccades were greatest when the visual target was synchronous with or leading the auditory target, and when the S/N ratio of the auditory target was lowest. Further, the improvements in saccade accuracy were greater in elevation than in azimuth. A control experiment demonstrated that a portion of the improvements in SRT could be attributable to a warning-cue mechanism, but that the improvements in saccade accuracy depended on the spatial register of the stimuli. These results agree well with earlier electrophysiological results obtained from the midbrain superior colliculus (SC) of anesthetized preparations, and we argue that they demonstrate multisensory integration of auditory and visual signals in a complex, quasi-natural environment. A conceptual model incorporating the SC is presented to explain the observed data.

Acoustic Stimulation↗
PubMed2005

An auditory brain-computer interface based on the self-regulation of slow cortical potentials.

OBJECTIVES: Communication support for severely paralyzed patients with visual impairment is needed. Therefore, the feasibility of a brain-computer interface (BCI) using auditory stimuli alone, based on the self-regulation of slow cortical potentials (SCPs), was investigated. METHODS: Auditory stimuli were used for task and feedback presentation in an SCP self-regulation paradigm. Voluntarily produced SCP responses and measures of communication performance were compared between 3 groups (total of N = 59) of visual, auditory, and cross-modal visual-auditory modality. Electroencephalogram recordings and training from Cz-mastoids were carried out on 3 consecutive sessions. Data of 1500 trials per subject were collected. RESULTS: Best performance was achieved for the visual, followed by the auditory condition. The performance deficit of the auditory condition was partly due to decreased self-produced positivity. Larger SCP response variability also accounted for lower performance of the auditory condition. Cross-modally presented stimuli did not lead to significant learning and control of SCP. CONCLUSIONS: Brain-computer communication using auditory stimuli only is possible. Smaller cortical positivity achieved in the auditory condition, as compared to the visual condition, may be a consequence of increased selective attention to simultaneously presented auditory stimuli. To optimize performance, auditory stimuli characteristics may have to be adapted. Other suggestions for enhancement of communication performance with auditory stimuli are discussed.

Adult↗
PubMed1985

Experience alters the spatial tuning of auditory units in the optic tectum during a sensitive period in the barn owl.

The auditory spatial tuning of bimodal (auditory-visual) units in the optic tectum of the barn owl was altered by raising animals with one ear occluded. Changes in spatial tuning were assessed by comparing the location of a unit's auditory best area with that of its visual receptive field. As shown previously, auditory best areas are aligned with visual receptive fields in the tecta of normal birds (Knudsen, E. I. (1982) J. Neurosci. 2: 1177-1194). It was demonstrated in this study that, when birds were raised with one ear occluded, best areas and visual receptive fields were aligned only as long as the earplug was in place. When the earplug was removed, best areas and visual receptive fields became misaligned, indicating that a change in auditory spatial tuning had taken place during the period of occlusion. However, in a bird that received an earplug as an adult, no such alterations in auditory spatial tuning were observed; even after 1 year of monaural occlusion, auditory best areas and visual receptive fields were misaligned so long as the earplug was in place, and were aligned when the earplug was removed. These results suggest that exposure to abnormal localization cues modifies the auditory spatial tuning of tectal units only during a restricted, sensitive period early in development. After the earplug was removed from a juvenile bird that had been raised with an occluded ear, the initial misalignment between auditory best areas and visual receptive fields decreased gradually over a period of weeks. In contrast, when earplugs were removed from two adult birds that had been raised with monaural occlusions, auditory-visual misalignments persisted for as long as measurements were made, which was up to 1 year after earplug removal. These data indicate that auditory cues become permanently associated with locations in visual space during a critical period which draws to a close at about the age when the animal reaches adulthood. Horseradish peroxidase was injected into two optic tecta (in a single animal) that contained units with permanently altered auditory spatial tuning. The positions of retrogradely labeled cells in the external nucleus of the inferior colliculus (ICX) were the same as those observed in control birds (Knudsen, E. I., and P. F. Knudsen (1983) J. Comp. Neurol. 218: 187-196). Thus, the changes in spatial tuning were not due to a shift in the topographic projection from the ICX to the optic tectum.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2003

Contribution of psychoacoustics and neuroaudiology in revealing correlation of mental disorders with central auditory processing disorders.

BACKGROUND: Psychoacoustics is a fascinating developing field concerned with the evaluation of the hearing sensation as an outcome of a sound or speech stimulus. Neuroaudiology with electrophysiologic testing, records the electrical activity of the auditory pathways, extending from the 8th cranial nerve up to the cortical auditory centers as a result of external auditory stimuli. Central Auditory Processing Disorders may co-exist with mental disorders and complicate diagnosis and outcome. DESIGN: A MEDLINE search was conducted to search for papers concerning the association between Central Auditory Processing Disorders and mental disorders. The research focused on the diagnostic methods providing the inter-connection of various mental disorders and central auditory deficits. MEASUREMENTS AND MAIN RESULTS: The medline research revealed 564 papers when using the keywords 'auditory deficits' and 'mental disorders'. 79 papers were referring specifically to Central Auditory Processing Disorders in connection with mental disorders. 175 papers were related to Schizophrenia, 126 to learning disabilities, 29 to Parkinson's disease, 88 to dyslexia and 39 to Alzheimer's disease. Assessment of the Central Auditory System is carried out through a great variety of tests that fall into two main categories: psychoacoustic and electrophysiologic testing. Different specialties are involved in the diagnosis and management of Central Auditory Processing Disorders as well as the mental disorders that may co-exist with them. As a result it is essential that they are all aware of the possibilities in diagnostic procedures. CONCLUSIONS: Considerable evidence exists that mental disorders may correlate with CAPD and this correlation could be revealed through psychoacoustics and neuroaudiology. Mental disorders that relate to Central Auditory Processing Disorders are: Schizophrenia, attention deficit disorders, Alzheimer's disease, learning disabilities, dyslexia, depression, auditory hallucinations, Parkinson's disease, alcoholism, anorexia and childhood mental retardation. Clinical awareness should be high in order for doctors of the two specialties, psychiatry and otorhinolaryngology-audiology to collaborate.

Journal Article↗
PubMed1991

Stretched and upside-down maps of auditory space in the optic tectum of blind-reared owls; acoustic basis and behavioral correlates.

Vision during early life plays an important role in calibrating sound localization behavior. This study investigates the effects of visual deprivation on sound localization and on the neural representation of auditory space. Nine barn owls were raised with eyelids sutured closed; one owl was congenitally anophthalmic. Data from these birds were compared with data from owls raised with normal visual experience. Sound localization behavior was significantly less precise in blind-reared owls than in normal owls. The scatter of localization errors was particularly large in elevation, though it was abnormally large in both dimensions. However, there was no systematic bias to the localization errors measured over a range of source locations. This indicates that the representation of auditory space is degraded in some way for blind-reared owls, but on average is properly calibrated. The spatial tuning of auditory neurons in the optic tectum was studied in seven of the blind-reared owls to assess the effects of early visual deprivation on the neural representation of auditory space. In normal owls, units in the optic tectum are sharply tuned for sound source location and are organized systematically according to the locations of their receptive fields to form a map of auditory space. In blind-reared owls, the following auditory properties were abnormal: (1) auditory tuning for source elevation was abnormally broad, (2) the progression of the azimuths and elevations of auditory receptive fields across the tectum was erratic, and (3) in five of the seven owls, the auditory representation of elevation was systematically stretched, and in the two others large portions of the representation of elevation were flipped upside down. The following unit properties were apparently unaffected by blind rearing: (1) the sharpness of tuning for sound source azimuth, (2) the orientation of the auditory representation of azimuth, and (3) the mutual alignment of the auditory and visual receptive fields in the region of the tectum representing the area of space directly in front of the animal. The data demonstrate that the brain is capable of generating an auditory map of space without vision, but that the normal precision and topography of the map depend on visual experience. The space map results from the tuning of tectal units for interaural intensity differences (IIDs) and interaural time differences (ITDs; Olsen et al., 1989).(ABSTRACT TRUNCATED AT 400 WORDS)

Acoustic Stimulation↗
PubMed1997

Auditory development of the hearing child.

Auditory perception is defined, here, as the interpretation of sensory evidence, derived from sound, in terms of the objects and events that caused the sound. Like other kinds of perception, it involves the use, not only of sensory evidence, but also of contextual evidence, prior knowledge, memory, attention, and processing skills. Auditory speech perception is special because the events to be perceived are those of language. Similarly, the listener's knowledge base and processing skills must include those related to language in general, and spoken language in particular. The auditory system is complete and functional at birth but myelination continues for several years in the higher auditory pathways. This pattern of anatomical maturation is reflected in electrophysiological responses. Similarly, infants display sophisticated discrimination and recognition ability but psychoacoustic performance does not reach adult levels for several years. Empirical data on the development of auditory processing are sparse, but much work has been done on auditory speech perception. Infants at 6 months demonstrate the beginnings of phonemic classification, and performance improves during childhood in a variety of areas. These include: phonetic contrast perception, phoneme recognition, perception of speech in noise, selective attention, and the use of linguistic context. Experience obviously plays a key role in the development of the knowledge and skills required for auditory perception in general and auditory speech perception in particular. It is tempting to assume that the sensory evidence available to the developing child is determined only by the functional integrity of the peripheral auditory system, independent of auditory experience. There is, however, increasing evidence in animals of the influence of auditory experience on the organization of the auditory pathways. Such organization could increase the sensory evidence made available from patterns of neural excitation produced in the cochlea.

Adolescent↗
PubMed2004

A dominantly inherited progressive deafness affecting distal auditory nerve and hair cells.

We have studied 72 members belonging to a large kindred with a hearing disorder inherited in an autosomal dominant pattern. We used audiological, physiological, and psychoacoustic measures to characterize the hearing disorders. The initial phenotypic features of the hearing loss are of an auditory neuropathy (AN) with abnormal auditory nerve and brainstem responses (ABRs) and normal outer hair cell functions [otoacoustic emissions (OAEs) and cochlear microphonics (CMs)]. Psychoacoustic studies revealed profound abnormalities of auditory temporal processes (gap detection, amplitude modulation detection, speech discrimination) and frequency processes (difference limens) beyond that seen in hearing impairment accompanying cochlear sensory disorders. The hearing loss progresses over 10-20 years to also involve outer hair cells, producing a profound sensorineural hearing loss with absent ABRs and OAEs. Affected family members do not have evidence of other cranial or peripheral neuropathies. There was a marked improvement of auditory functions in three affected family members studied after cochlear implantation with return of electrically evoked auditory brainstem responses (EABRs), auditory temporal processes, and speech recognition. These findings are compatible with a distal auditory nerve disorder affecting one or all of the components in the auditory periphery including terminal auditory nerve dendrites, inner hair cells, and the synapses between inner hair cells and auditory nerve. There is relative sparing of auditory ganglion cells and their axons.

Acoustic Impedance Tests↗
PubMed1995

Significance of auditory brain stem response and gadolinium-enhanced magnetic resonance imaging for idiopathic sudden sensorineural hearing loss.

Previous studies tried to correlate prognosis and response to oral corticosteroids in patients with idiopathic sudden sensorineural hearing loss to such factors as the age of the patient, presence of vertigo, shape of the audiogram, or severity of the hearing loss. However, temporal bone histopathologic evidence shows that idiopathic sudden sensorineural hearing loss may be caused by cochleitis or cochlear nerve neuritis. Herein we report results of a retrospective study of 96 consecutive patients with idiopathic sudden sensorineural hearing loss who were evaluated with auditory brain stem responses and gadolinium-enhanced magnetic resonance imaging. Results of the auditory brain stem response and magnetic resonance imaging were correlated with hearing outcome. Follow-up was available for 65 patients: 14 with abnormal and 51 with normal auditory brain stem responses. The overall rate of hearing recovery or improvement was 65% in the normal auditory brain stem response group compared with 43% in the abnormal auditory brain stem response group (p = 0.07). Among the 38 patients treated with a tapering course of oral corticosteroids, the recovery or improvement rate was 83% for those with normal auditory brain stem responses and 56% for those with abnormal auditory brain stem responses (p < 0.05). Of the 27 patients who did not receive steroid therapy, the improvement rate was 41% in those with normal auditory brain stem responses and 20% in those with abnormal auditory brain stem responses (p = 0.09). Magnetic resonance imaging with gadolinium was obtained on all 14 patients with abnormal auditory brain stem responses but on none with normal auditory brain stem responses.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1992

Selective attention in auditory processing as reflected by event-related brain potentials.

Measures of event-related brain potentials (ERPs) have revealed two kinds of selective-attention mechanisms that operate on attended and unattended auditory stimuli. The processing negativity of the ERP reveals a mechanism of intramodal selective attention in the auditory cortex controlled by the frontal cortex. This mechanism selects attended auditory stimuli for further processing when they differ from unattended stimuli in location or tonal frequency. Studies of intermodal selective attention have compared auditory ERPs during auditory and visual attention. At least in part different brain mechanisms may be involved in the selection of auditory stimuli among other auditory stimuli (intramodal selective attention) and in the selection of auditory stimuli among visual stimuli (intermodal selective attention). This is suggested by the results showing that the earlier component of the processing negativity, which is generated in the auditory cortex during intramodal selective attention, differs in scalp distribution from the early attention-related negativity elicited during intermodal selective attention. With respect to the unattended auditory stimuli, ERP studies of selective attention suggest that physical features of these stimuli are extensively processed. This is shown by the mismatch negativity component of the ERP, which is usually elicited by infrequent physical deviations in an auditory stimulus sequence both when this sequence is attended and when it is ignored. This would be impossible if the physical stimulus features were not extensively processed, even in the absence of attention.

Arousal↗