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Hearing Research May 2014Acoustic communication requires gathering, transforming, and interpreting diverse sound cues. To achieve this, all the spatial and temporal features of complex sound... (Review)
Review
Acoustic communication requires gathering, transforming, and interpreting diverse sound cues. To achieve this, all the spatial and temporal features of complex sound stimuli must be captured in the firing patterns of the primary sensory neurons and then accurately transmitted along auditory pathways for additional processing. The mammalian auditory system relies on several synapses with unique properties in order to meet this task: the auditory ribbon synapses, the endbulb of Held, and the calyx of Held. Each of these synapses develops morphological and electrophysiological characteristics that enable the remarkably precise signal transmission necessary for conveying the miniscule differences in timing that underly sound localization. In this article, we review the current knowledge of how these synapses develop and mature to acquire the specialized features necessary for the sense of hearing.
Topics: Acoustic Stimulation; Animals; Auditory Pathways; Auditory Perception; Hearing; Humans; Mechanotransduction, Cellular; Morphogenesis; Pressure; Synapses; Synaptic Transmission; Vibration
PubMed: 24508369
DOI: 10.1016/j.heares.2014.01.007 -
Frontiers in Neural Circuits 2016Glial cells, previously thought to have generally supporting roles in the central nervous system, are emerging as essential contributors to multiple aspects of neuronal... (Review)
Review
Glial cells, previously thought to have generally supporting roles in the central nervous system, are emerging as essential contributors to multiple aspects of neuronal circuit function and development. This review focuses on the contributions of glial cells to the development of auditory pathways in the brainstem. These pathways display specialized synapses and an unusually high degree of precision in circuitry that enables sound source localization. The development of these pathways thus requires highly coordinated molecular and cellular mechanisms. Several classes of glial cells, including astrocytes, oligodendrocytes and microglia, have now been explored in these circuits in both avian and mammalian brainstems. Distinct populations of astrocytes are found over the course of auditory brainstem maturation. Early appearing astrocytes are associated with spatial compartments in the avian auditory brainstem. Factors from late appearing astrocytes promote synaptogenesis and dendritic maturation, and astrocytes remain integral parts of specialized auditory synapses. Oligodendrocytes play a unique role in both birds and mammals in highly regulated myelination essential for proper timing to decipher interaural cues. Microglia arise early in brainstem development and may contribute to maturation of auditory pathways. Together these studies demonstrate the importance of non-neuronal cells in the assembly of specialized auditory brainstem circuits.
Topics: Animals; Auditory Pathways; Brain Stem; Neuroglia
PubMed: 27818624
DOI: 10.3389/fncir.2016.00083 -
Hearing Research Jan 2011The dual-pathway model of auditory cortical processing assumes that two largely segregated processing streams originating in the lateral belt subserve the two main... (Review)
Review
The dual-pathway model of auditory cortical processing assumes that two largely segregated processing streams originating in the lateral belt subserve the two main functions of hearing: identification of auditory "objects", including speech; and localization of sounds in space (Rauschecker and Tian, 2000). Evidence has accumulated, chiefly from work in humans and nonhuman primates, that an antero-ventral pathway supports the former function, whereas a postero-dorsal stream supports the latter, i.e processing of space and motion-in-space. In addition, the postero-dorsal stream has also been postulated to subserve some functions of speech and language in humans. A recent review (Rauschecker and Scott, 2009) has proposed the possibility that both functions of the postero-dorsal pathway can be subsumed under the same structural forward model: an efference copy sent from prefrontal and premotor cortex provides the basis for "optimal state estimation" in the inferior parietal lobe and in sensory areas of the posterior auditory cortex. The current article corroborates this model by adding and discussing recent evidence.
Topics: Animals; Auditory Cortex; Auditory Pathways; Auditory Perception; Cats; Feedback, Sensory; Haplorhini; Humans; Language; Models, Neurological; Parietal Lobe; Prefrontal Cortex; Psychomotor Performance; Space Perception; Speech Perception
PubMed: 20850511
DOI: 10.1016/j.heares.2010.09.001 -
Behavioural Brain Research Dec 2015Hearing perception in individuals with auditory hallucinations has not been well studied. Auditory hallucinations have previously been shown to involve primary auditory...
Hearing perception in individuals with auditory hallucinations has not been well studied. Auditory hallucinations have previously been shown to involve primary auditory cortex activation. This activation suggests that auditory hallucinations activate the terminal of the auditory pathway as if auditory signals are submitted from the cochlea, and that a hallucinatory event is therefore perceived as hearing. The primary auditory cortex is stimulated by some unknown source that is outside of the auditory pathway. The current study aimed to assess the outcomes of stimulating the primary auditory cortex through the auditory pathway in individuals who have experienced auditory hallucinations. Sixteen patients with schizophrenia underwent functional magnetic resonance imaging (fMRI) sessions, as well as hallucination assessments. During the fMRI session, auditory stimuli were presented in one-second intervals at times when scanner noise was absent. Participants listened to auditory stimuli of sine waves (SW) (4-5.5kHz), English words (EW), and acoustically reversed English words (arEW) in a block design fashion. The arEW were employed to deliver the sound of a human voice with minimal linguistic components. Patients' auditory hallucination severity was assessed by the auditory hallucination item of the Brief Psychiatric Rating Scale (BPRS). During perception of arEW when compared with perception of SW, bilateral activation of the globus pallidus correlated with severity of auditory hallucinations. EW when compared with arEW did not correlate with auditory hallucination severity. Our findings suggest that the sensitivity of the globus pallidus to the human voice is associated with the severity of auditory hallucination.
Topics: Adult; Auditory Cortex; Auditory Pathways; Auditory Perception; Female; Hallucinations; Humans; Language; Magnetic Resonance Imaging; Male; Middle Aged; Schizophrenia; Self Report; Temporal Lobe
PubMed: 26275927
DOI: 10.1016/j.bbr.2015.08.009 -
Journal of Neurophysiology Feb 2022Noise-induced hearing deficits are important health problems in the industrialized world. As the underlying physiological dysfunctions are not well understood, research... (Comparative Study)
Comparative Study
Noise-induced hearing deficits are important health problems in the industrialized world. As the underlying physiological dysfunctions are not well understood, research in suitable animal models is urgently needed. Three rodent species (Mongolian gerbil, rat, and mouse) were studied to compare the temporal dynamics of noise-induced hearing loss after identical procedures of noise exposure. Auditory brainstem responses (ABRs) were measured before, during, and up to 8 wk after noise exposure for threshold determination and ABR waveform analysis. Trauma induction with stepwise increasing sound pressure level was interrupted by five interspersed ABR measurements. Comparing short- and long-term dynamics underlying the following noise-induced hearing loss revealed diverging time courses between the three species. Hearing loss occurred early on during noise exposure in all three rodent species at or above trauma frequency. Initial noise level (105 dB SPL) was most effective in rats whereas the delayed level increase to 115 dB SPL affected mice much stronger. Induced temporary threshold shifts in rats and mice were larger in animals with lower pretrauma ABR thresholds. The increase in activity (gain) along the auditory pathway was derived by comparing the amplitudes of short- and long-latency ABR waveform components. Directly after trauma, significant effects were found for rats (decreasing gain) and mice (increasing gain) whereas gerbils revealed high individual variability in gain changes. Taken together, our comparative study revealed pronounced species-specific differences in the development of noise-induced hearing loss and the related processing along the auditory pathway. We compared deficits after noise trauma in different rodents that are typically used in hearing research (Mongolian gerbil, rat, and mouse). We observed noise-induced threshold changes and alterations in the activity of processing auditory information along the ascending auditory pathway. Our results reveal pronounced differences in the characteristics of trauma-induced damage in these different rodent groups.
Topics: Animals; Auditory Pathways; Auditory Threshold; Behavior, Animal; Disease Models, Animal; Evoked Potentials, Auditory, Brain Stem; Gerbillinae; Hearing Loss, Noise-Induced; Mice; Noise; Rats; Species Specificity
PubMed: 35020518
DOI: 10.1152/jn.00081.2021 -
Hearing Research Aug 2014We live in a world imbued with a rich mixture of complex sounds. Successful acoustic communication requires the ability to extract meaning from those sounds, even when... (Review)
Review
We live in a world imbued with a rich mixture of complex sounds. Successful acoustic communication requires the ability to extract meaning from those sounds, even when degraded. One strategy used by the auditory system is to harness high-level contextual cues to modulate the perception of incoming sounds. An ideal substrate for this process is the massive set of top-down projections emanating from virtually every level of the auditory system. In this review, we provide a molecular and circuit-level description of one of the largest of these pathways: the auditory corticocollicular pathway. While its functional role remains to be fully elucidated, activation of this projection system can rapidly and profoundly change the tuning of neurons in the inferior colliculus. Several specific issues are reviewed. First, we describe the complex heterogeneous anatomical organization of the corticocollicular pathway, with particular emphasis on the topography of the pathway. We also review the laminar origin of the corticocollicular projection and discuss known physiological and morphological differences between subsets of corticocollicular cells. Finally, we discuss recent findings about the molecular micro-organization of the inferior colliculus and how it interfaces with corticocollicular termination patterns. Given the assortment of molecular tools now available to the investigator, it is hoped that his review will help guide future research on the role of this pathway in normal hearing.
Topics: Acoustic Stimulation; Animals; Auditory Cortex; Auditory Pathways; Cues; Humans; Inferior Colliculi; Neural Pathways; Neuronal Plasticity; Neurons; Perception; Sound
PubMed: 24911237
DOI: 10.1016/j.heares.2014.05.004 -
Effect of perinatal and postnatal thiamine deficiency on auditory pathway of the Wistar-Albino rats.Brazilian Journal of Otorhinolaryngology 2023In this study, we created an animal model to demonstrate the effects of thiamine on the hearing pathways of new-borns during pregnancy and lactation by inducing a...
OBJECTIVE
In this study, we created an animal model to demonstrate the effects of thiamine on the hearing pathways of new-borns during pregnancy and lactation by inducing a dietary thiamine deficiency in the mother.
METHODS
The study included 16 female Wistar albino rats. The animals were separated into four groups and provided the appropriate amounts of dietary thiamine according to their groups during pre-pregnancy, pregnancy, and lactation periods. Three pups from each mother were included in the study, and 12 pups were selected from each group. On the fortieth day after birth, the auditory pathways of 48 pups in the 4 groups were examined electro physiologically and ultra-structurally.
RESULTS
In Group N-N, morphology of hair cells stereocilia degeneration was not obtained in all turns of cochlea. In Group N-T, Inner Hair Cells (IHCs) and Outher Hair Cells (OHCs) stereocilia didn't show degeneration in all turns of cochlea but had rupture inrows of HCs stereocilia. In group T-N IHCs stereocilia less degeneration was observed in all turns of cochlea. OHC stereocilia partial loss was observed only in basal turn of cochlea. In Group T-T IHCs stereocilia was observed less degeneration and rupture in all turns of cochlea.
CONCLUSION
Thiamine is vital for the development of cochlear hair cells during both prenatal and postnatal periods. Even partial deficiency of thiamine causes significant degeneration to the auditory pathway.
LEVEL OF EVIDENCE
The level of evidence of this article is 5. This article is an experimental animal and laboratory study.
Topics: Pregnancy; Animals; Rats; Female; Auditory Pathways; Rats, Wistar; Hair Cells, Auditory; Cochlea; Thiamine Deficiency; Thiamine; Hair Cells, Auditory, Outer
PubMed: 36446695
DOI: 10.1016/j.bjorl.2022.10.053 -
Frontiers in Neural Circuits 2021Predictive processing, a leading theoretical framework for sensory processing, suggests that the brain constantly generates predictions on the sensory world and that... (Review)
Review
Predictive processing, a leading theoretical framework for sensory processing, suggests that the brain constantly generates predictions on the sensory world and that perception emerges from the comparison between these predictions and the actual sensory input. This requires two distinct neural elements: generative units, which encode the model of the sensory world; and prediction error units, which compare these predictions against the sensory input. Although predictive processing is generally portrayed as a theory of cerebral cortex function, animal and human studies over the last decade have robustly shown the ubiquitous presence of prediction error responses in several nuclei of the auditory, somatosensory, and visual subcortical pathways. In the auditory modality, prediction error is typically elicited using so-called oddball paradigms, where sequences of repeated pure tones with the same pitch are at unpredictable intervals substituted by a tone of deviant frequency. Repeated sounds become predictable promptly and elicit decreasing prediction error; deviant tones break these predictions and elicit large prediction errors. The simplicity of the rules inducing predictability make oddball paradigms agnostic about the origin of the predictions. Here, we introduce two possible models of the organizational topology of the predictive processing auditory network: (1) the global view, that assumes that predictions on the sensory input are generated at high-order levels of the cerebral cortex and transmitted in a cascade of generative models to the subcortical sensory pathways; and (2) the local view, that assumes that independent local models, computed using local information, are used to perform predictions at each processing stage. In the global view information encoding is optimized globally but biases sensory representations along the entire brain according to the subjective views of the observer. The local view results in a diminished coding efficiency, but guarantees in return a robust encoding of the features of sensory input at each processing stage. Although most experimental results to-date are ambiguous in this respect, recent evidence favors the global model.
Topics: Acoustic Stimulation; Animals; Auditory Cortex; Auditory Pathways; Auditory Perception; Brain; Cerebral Cortex; Humans
PubMed: 33776657
DOI: 10.3389/fncir.2021.644743 -
Neuroscience Aug 2014As the major excitatory neurotransmitter used in the vertebrate brain, glutamate activates ionotropic and metabotropic glutamate receptors (mGluRs), which mediate fast... (Review)
Review
As the major excitatory neurotransmitter used in the vertebrate brain, glutamate activates ionotropic and metabotropic glutamate receptors (mGluRs), which mediate fast and slow neuronal actions, respectively. Important modulatory roles of mGluRs have been shown in many brain areas, and drugs targeting mGluRs have been developed for the treatment of brain disorders. Here, I review studies on mGluRs in the auditory system. Anatomical expression of mGluRs in the cochlear nucleus has been well characterized, while data for other auditory nuclei await more systematic investigations at both the light and electron microscopy levels. The physiology of mGluRs has been extensively studied using in vitro brain slice preparations, with a focus on the lower auditory brainstem in both mammals and birds. These in vitro physiological studies have revealed that mGluRs participate in neurotransmission, regulate ionic homeostasis, induce synaptic plasticity, and maintain the balance between excitation and inhibition in a variety of auditory structures. However, very few in vivo physiological studies on mGluRs in auditory processing have been undertaken at the systems level. Many questions regarding the essential roles of mGluRs in auditory processing still remain unanswered and more rigorous basic research is warranted.
Topics: Animals; Auditory Pathways; Auditory Perception; Humans; Receptors, Metabotropic Glutamate
PubMed: 24909898
DOI: 10.1016/j.neuroscience.2014.05.057 -
Frontiers in Neural Circuits 2017During development, the organization of the auditory system into distinct functional subcircuits depends on the spatially and temporally ordered sequence of neuronal... (Review)
Review
During development, the organization of the auditory system into distinct functional subcircuits depends on the spatially and temporally ordered sequence of neuronal specification, differentiation, migration and connectivity. Regional patterning along the antero-posterior axis and neuronal subtype specification along the dorso-ventral axis intersect to determine proper neuronal fate and assembly of rhombomere-specific auditory subcircuits. By taking advantage of the increasing number of transgenic mouse lines, recent studies have expanded the knowledge of developmental mechanisms involved in the formation and refinement of the auditory system. Here, we summarize several findings dealing with the molecular and cellular mechanisms that underlie the assembly of central auditory subcircuits during mouse development, focusing primarily on the rhombomeric and dorso-ventral origin of auditory nuclei and their associated molecular genetic pathways.
Topics: Animals; Auditory Pathways; Cell Differentiation; Cell Movement; Gene Expression Regulation, Developmental; Mice; Neurons
PubMed: 28469562
DOI: 10.3389/fncir.2017.00018