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Developmental Neurobiology Feb 2018Myelin allows for the rapid and precise timing of action potential propagation along neuronal circuits and is essential for healthy auditory system function. In this... (Review)
Review
Myelin allows for the rapid and precise timing of action potential propagation along neuronal circuits and is essential for healthy auditory system function. In this article, we discuss what is currently known about myelin in the auditory system with a focus on the timing of myelination during auditory system development, the role of myelin in supporting peripheral and central auditory circuit function, and how various myelin pathologies compromise auditory information processing. Additionally, in keeping with the increasing recognition that myelin is dynamic and is influenced by experience throughout life, we review the growing evidence that auditory sensory deprivation alters myelin along specific segments of the brain's auditory circuit. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 78: 80-92, 2018.
Topics: Animals; Auditory Pathways; Humans; Myelin Sheath; Neuronal Plasticity
PubMed: 28925106
DOI: 10.1002/dneu.22538 -
Brain Structure & Function Jul 2021Tinnitus is the perception of a 'ringing' sound without an acoustic source. It is generally accepted that tinnitus develops after peripheral hearing loss and is... (Review)
Review
Tinnitus is the perception of a 'ringing' sound without an acoustic source. It is generally accepted that tinnitus develops after peripheral hearing loss and is associated with altered auditory processing. The thalamus is a crucial relay in the underlying pathways that actively shapes processing of auditory signals before the respective information reaches the cerebral cortex. Here, we review animal and human evidence to define thalamic function in tinnitus. Overall increased spontaneous firing patterns and altered coherence between the thalamic medial geniculate body (MGB) and auditory cortices is observed in animal models of tinnitus. It is likely that the functional connectivity between the MGB and primary and secondary auditory cortices is reduced in humans. Conversely, there are indications for increased connectivity between the MGB and several areas in the cingulate cortex and posterior cerebellar regions, as well as variability in connectivity between the MGB and frontal areas regarding laterality and orientation in the inferior, medial and superior frontal gyrus. We suggest that these changes affect adaptive sensory gating of temporal and spectral sound features along the auditory pathway, reflecting dysfunction in an extensive thalamo-cortical network implicated in predictive temporal adaptation to the auditory environment. Modulation of temporal characteristics of input signals might hence factor into a thalamo-cortical dysrhythmia profile of tinnitus, but could ultimately also establish new directions for treatment options for persons with tinnitus.
Topics: Animals; Auditory Cortex; Auditory Pathways; Geniculate Bodies; Humans; Thalamus; Tinnitus
PubMed: 33934235
DOI: 10.1007/s00429-021-02284-x -
International Journal of... Feb 2015The auditory system is designed to transform acoustic information from low-level sensory representations into perceptual representations. These perceptual... (Review)
Review
The auditory system is designed to transform acoustic information from low-level sensory representations into perceptual representations. These perceptual representations are the computational result of the auditory system's ability to group and segregate spectral, spatial and temporal regularities in the acoustic environment into stable perceptual units (i.e., sounds or auditory objects). Current evidence suggests that the cortex-specifically, the ventral auditory pathway-is responsible for the computations most closely related to perceptual representations. Here, we discuss how the transformations along the ventral auditory pathway relate to auditory percepts, with special attention paid to the processing of vocalizations and categorization, and explore recent models of how these areas may carry out these computations.
Topics: Acoustic Stimulation; Acoustics; Animals; Auditory Cortex; Auditory Pathways; Auditory Perception; Brain Mapping; Humans; Sound
PubMed: 24681354
DOI: 10.1016/j.ijpsycho.2014.03.004 -
International Journal of... Feb 2015
Topics: Animals; Auditory Cortex; Auditory Pathways; Auditory Perception; Humans; Neurosciences
PubMed: 25645027
DOI: 10.1016/j.ijpsycho.2015.01.008 -
Hearing Research Mar 2018Auditory research has a rich history of combining experimental evidence with computational simulations of auditory processing in order to deepen our theoretical... (Review)
Review
Auditory research has a rich history of combining experimental evidence with computational simulations of auditory processing in order to deepen our theoretical understanding of how sound is processed in the ears and in the brain. Despite significant progress in the amount of detail and breadth covered by auditory models, for many components of the auditory pathway there are still different model approaches that are often not equivalent but rather in conflict with each other. Similarly, some experimental studies yield conflicting results which has led to controversies. This can be best resolved by a systematic comparison of multiple experimental data sets and model approaches. Binaural processing is a prominent example of how the development of quantitative theories can advance our understanding of the phenomena, but there remain several unresolved questions for which competing model approaches exist. This article discusses a number of current unresolved or disputed issues in binaural modelling, as well as some of the significant challenges in comparing binaural models with each other and with the experimental data. We introduce an auditory model framework, which we believe can become a useful infrastructure for resolving some of the current controversies. It operates models over the same paradigms that are used experimentally. The core of the proposed framework is an interface that connects three components irrespective of their underlying programming language: The experiment software, an auditory pathway model, and task-dependent decision stages called artificial observers that provide the same output format as the test subject.
Topics: Acoustic Stimulation; Auditory Pathways; Auditory Perception; Cues; Hearing; Humans; Models, Psychological; Psychoacoustics; Sound Localization; Speech Intelligibility; Speech Perception; Time Factors
PubMed: 29208336
DOI: 10.1016/j.heares.2017.11.010 -
Nature Reviews. Neuroscience Jul 2019There are functional and anatomical distinctions between the neural systems involved in the recognition of sounds in the environment and those involved in the... (Review)
Review
There are functional and anatomical distinctions between the neural systems involved in the recognition of sounds in the environment and those involved in the sensorimotor guidance of sound production and the spatial processing of sound. Evidence for the separation of these processes has historically come from disparate literatures on the perception and production of speech, music and other sounds. More recent evidence indicates that there are computational distinctions between the rostral and caudal primate auditory cortex that may underlie functional differences in auditory processing. These functional differences may originate from differences in the response times and temporal profiles of neurons in the rostral and caudal auditory cortex, suggesting that computational accounts of primate auditory pathways should focus on the implications of these temporal response differences.
Topics: Acoustic Stimulation; Animals; Auditory Cortex; Auditory Pathways; Auditory Perception; Humans
PubMed: 30918365
DOI: 10.1038/s41583-019-0160-2 -
Hearing Research Nov 2020Sensory input has profound effects on neuronal organization and sensory maps in the brain. The mechanisms regulating plasticity of the auditory pathway have been... (Review)
Review
Sensory input has profound effects on neuronal organization and sensory maps in the brain. The mechanisms regulating plasticity of the auditory pathway have been revealed by examining the consequences of altered auditory input during both developmental critical periods-when plasticity facilitates the optimization of neural circuits in concert with the external environment-and in adulthood-when hearing loss is linked to the generation of tinnitus. In this review, we summarize research identifying the molecular, cellular, and circuit-level mechanisms regulating neuronal organization and tonotopic map plasticity during developmental critical periods and in adulthood. These mechanisms are shared in both the juvenile and adult brain and along the length of the auditory pathway, where they serve to regulate disinhibitory networks, synaptic structure and function, as well as structural barriers to plasticity. Regulation of plasticity also involves both neuromodulatory circuits, which link plasticity with learning and attention, as well as ascending and descending auditory circuits, which link the auditory cortex and lower structures. Further work identifying the interplay of molecular and cellular mechanisms associating hearing loss-induced plasticity with tinnitus will continue to advance our understanding of this disorder and lead to new approaches to its treatment.
Topics: Auditory Cortex; Auditory Pathways; Deafness; Hearing Loss; Humans; Neuronal Plasticity; Tinnitus
PubMed: 32591097
DOI: 10.1016/j.heares.2020.107976 -
International Journal of... Nov 2019Auditory verbal hallucinations (AVH) are hallmark symptoms of schizophrenia and have been linked to abnormal activation, connectivity and integration within the... (Review)
Review
Auditory verbal hallucinations (AVH) are hallmark symptoms of schizophrenia and have been linked to abnormal activation, connectivity and integration within the auditory, language, and memory brain networks. The interhemispheric miscommunication theory of AVH is based on a steadily growing number of studies using a variety of modalities (EEG, fMRI, DTI) reporting that both altered integrity of the interhemispheric auditory pathways and disturbed functional gamma-band synchrony between right and left auditory cortices significantly contribute to abnormal auditory processing and the emergence of AVH. Moreover, initial studies using pharmacological EEG and H MR spectroscopy provided first insights into the underlying neurochemistry of AVH. It has been suggested that the observed interhemispheric gamma-band alterations might be mediated by an excitatory-to-inhibitory (E/I) imbalance due to dysfunction of N-methyl-d-aspartate receptor (NMDAR). In support, a potential NMDAR hypofunction is proposed to be compensated by increased levels of glutamate in prefrontal and auditory brain areas. In this mini-review paper, we used the levels of explanation approach and present how interhemispheric brain connectivity (brain-imaging level) corresponds to auditory perception (cognitive level), and eventually how these parameters are related to changes in neurotransmission (cellular level) and to the occurrence of AVH (clinical level). To the best of our knowledge, this is the first overview that overcomes traditional boundaries and presents converging evidence from different levels of knowledge that validate and support each other, and particularly point toward the role of an interhemispheric miscommunication in AVH.
Topics: Auditory Pathways; Auditory Perception; Brain; Electroencephalography; Hallucinations; Humans; Magnetic Resonance Imaging; Neural Pathways; Schizophrenia
PubMed: 30738815
DOI: 10.1016/j.ijpsycho.2019.02.002 -
Trends in Neurosciences Apr 2018Deafness causes speech to deteriorate, but whether this deterioration reflects an active or passive process is unclear. Birdsong - a learned vocal behavior that... (Review)
Review
Deafness causes speech to deteriorate, but whether this deterioration reflects an active or passive process is unclear. Birdsong - a learned vocal behavior that resembles speech in its dependence on auditory feedback - also deteriorates following deafening. In their 2000 paper, Brainard and Doupe showed that, following deafening, birdsong deteriorates through an active process mediated by a cortex-basal ganglia (BG) circuit.
Topics: Animals; Auditory Pathways; Auditory Perception; Deafness; Feedback, Sensory; Humans; Learning; Neuronal Plasticity
PubMed: 29602334
DOI: 10.1016/j.tins.2018.02.006 -
The Journal of Neuroscience : the... Oct 2019Discriminating between auditory signals of different affective value is critical for the survival and success of social interaction of an individual. Anatomical,...
Discriminating between auditory signals of different affective value is critical for the survival and success of social interaction of an individual. Anatomical, electrophysiological, imaging, and optogenetics approaches have established that the auditory cortex (AC) by providing auditory information to the lateral amygdala (LA) via long-range excitatory glutamatergic projections has an impact on sound-driven aversive/fear behavior. Here we test the hypothesis that the LA also receives GABAergic projections from the cortex. We addressed this fundamental question by taking advantage of optogenetics, anatomical, and electrophysiology approaches and directly examining the functional effects of cortical GABAergic inputs to LA neurons of the mouse (male/female) AC. We found that the cortex, via cortico-lateral-amygdala somatostatin neurons (CLA-SOM), has a direct inhibitory influence on the output of the LA principal neurons. Our results define a CLA long-range inhibitory circuit (CLA-SOM inhibitory projections → LA principal neurons) underlying the control of spike timing/generation in LA and LA-AC projecting neurons, and attributes a specific function to a genetically defined type of cortical long-range GABAergic neurons in CLA communication. It is very well established that cortical auditory inputs to the lateral amygdala are exclusively excitatory and that cortico-amygdala neuronal activity has been shown to be involved in sound-driven aversive/fear behavior. Here, for the first time, we show that the lateral amygdala receives long-range GABAergic projection from the auditory cortex and these form direct monosynaptic inhibitory connections onto lateral amygdala principal neurons. Our results define a cellular basis for direct inhibitory communication from auditory cortex to the lateral amygdala, suggesting that the timing and ratio of excitation and inhibition, two opposing forces in the mammalian cerebral cortex, can dynamically affect the output of the lateral amygdala, providing a general mechanism for fear/aversive behavior driven by auditory stimuli.
Topics: Amygdala; Animals; Auditory Cortex; Auditory Pathways; Fear; GABAergic Neurons; Glutamic Acid; Mice; Mice, Transgenic; Neural Inhibition; Neurons; Somatostatin
PubMed: 31511429
DOI: 10.1523/JNEUROSCI.1515-19.2019