Regulation of Inhibition in a Sound Localization Circuit PDF Download

Author: Briana J. Carroll
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Author: R. Michael Burger
Publisher: Frontiers Media SA
ISBN: 2889196674
Category : Auditory perception
Languages : en
Pages : 233

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There seems little doubt that from the earliest evolutionary beginnings, inhibition has been a fundamental feature of neuronal circuits - even the simplest life forms sense and interact with their environment, orienting or approaching positive stimuli while avoiding aversive stimuli. This requires internal signals that both drive and suppress behavior. Traditional descriptions of inhibition sometimes limit its role to the suppression of action potential generation. This view fails to capture the vast breadth of inhibitory function now known to exist in neural circuits. A modern perspective on inhibitory signaling comprises a multitude of mechanisms. For example, inhibition can act via a shunting mechanism to speed the membrane time constant and reduce synaptic integration time. It can act via G-protein coupled receptors to initiate second messenger cascades that influence synaptic strength. Inhibition contributes to rhythm generation and can even activate ion channels that mediate inward currents to drive action potential generation. Inhibition also appears to play a role in shaping the properties of neural circuitry over longer time scales. Experience-dependent synaptic plasticity in developing and mature neural circuits underlies behavioral memory and has been intensively studied over the past decade. At excitatory synapses, adjustments of synaptic efficacy are regulated predominantly by changes in the number and function of postsynaptic glutamate receptors. There is, however, increasing evidence for inhibitory modulation of target neuron excitability playing key roles in experience-dependent plasticity. One reason for our limited knowledge about plasticity at inhibitory synapses is that in most circuits, neurons receive convergent inputs from disparate sources. This problem can be overcome by investigating inhibitory circuits in a system with well-defined inhibitory nuclei and projections, each with a known computational function. Compared to other sensory systems, the auditory system has evolved a large number of subthalamic nuclei each devoted to processing distinct features of sound stimuli. This information once extracted is then re-assembled to form the percept the acoustic world around us. The well-understood function of many of these auditory nuclei has enhanced our understanding of inhibition's role in shaping their responses from easily distinguished inhibitory inputs. In particular, neurons devoted to processing the location of sound sources receive a complement of discrete inputs for which in vivo activity and function are well understood. Investigation of these areas has led to significant advances in understanding the development, physiology, and mechanistic underpinnings of inhibition that apply broadly to neuroscience. In this series of papers, we provide an authoritative resource for those interested in exploring the variety of inhibitory circuits and their function in auditory processing. We present original research and focused reviews touching on development, plasticity, anatomy, and evolution of inhibitory circuitry. We hope our readers will find these papers valuable and inspirational to their own research endeavors.

Author: Rebecca J. Curry
Publisher:
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Category :
Languages : en
Pages : 0

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The ability to localize sound in space is an important task for communication and survival in complex acoustic environments for both humans and animals. For localizing sound in the horizontal plane, differences in sound information received by each ear generates binaural cues, such as the interaural level difference (ILD). Using whole-cell recordings in brain slices, this work focuses on the basic properties of synaptic inhibition in the avian ILD circuit, as well as the modulation of inhibition in the mammalian ILD circuit, both of which are critical for understanding the range of cellular sound localization coding solutions. In birds, the posterior portion of the dorsal nucleus of the lateral lemniscus (LLDp) encodes the ILD, but little is known about the mechanisms of synaptic inhibition underlying the ILD coding. Here, I provide the first evidence confirming a monosynaptic inhibition driven by direct electrical and chemical stimulation of the contralateral LLDp. Additionally, inhibition to LLDp neurons was largely GABAergic, although there is evidence for a glycinergic component, and the low internal chloride concentration suggests a hyperpolarizing action of inhibition in this circuit. In mammals, the medial nucleus of the trapezoid body (MNTB) provides synaptic inhibition to many auditory brainstem nuclei including the mammalian ILD encoding nucleus, and thus contributes to ILD coding. However, not much is understood of the synaptic inhibition the MNTB itself receives and it remains entirely unknown how this inhibition is regulated. Here, I investigated group I metabotropic glutamate receptor (mGluR I) modulation of the glycinergic and GABAergic inputs to MNTB neurons in both wildtype (WT) mice and a fragile X syndrome (FXS) mouse model, in which the fragile X mental retardation gene 1 is knocked out (Fmr1 KO). Loss of the FMR protein results in exaggerated activity of mGluR I, allowing for comparisons of mGluR I function under normal and disordered conditions. Activation of group I mGluRs by 3,5-DHPG (200 ℗æM) increased sIPSC frequency and amplitude in both WT and Fmr1 KO neurons in a voltage-gated sodium channel dependent fashion for glycinergic transmission, but did not modulate glycinergic eIPSCs. For GABAergic transmission, 3,5-DHPG did not increase sIPSC frequency or amplitude, but did suppress eIPSCs in WT neurons. These findings suggest differential modulation by mGluR I on specific inhibitory neurotransmitters and specific neurotransmitter release modes. Together, the results provide new insight to the role of synaptic inhibition in the computation of sound localization across animal models, establishing a working cellular model for avian ILD coding and laying the foundation for the role of mGluR I modulation in the mammalian MNTB under normal and disease states.

Author: Edwin W. Rubel
Publisher: Springer
ISBN: 9781461274506
Category : Science
Languages : en
Pages : 0

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The contributors to this volume have provided a detailed and integrated introduction to the behavioural, anatomical, and physiological changes that occur in the auditory system of developing animals. Edwin W Rubel is Virginia Merrill Bloedel Professor of Hearing Sciences at the Virginia Merrill Bloedel Hearing Research Center at the University of Washington, Arthur N. Popper is Professor and Chair of the Department of Zoology at the University of Maryland, while Richard R. Fay is Associate Director of the Parmly Hearing Institute and Professor of Psychology at Loyola University of Chicago. Each volume in this series is independent and authoritative; taken as a set, the series will be the definitive resource in the field.

Author: Achim Klug
Publisher: Frontiers Media SA
ISBN: 2889761592
Category : Science
Languages : en
Pages : 149

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Languages : en
Pages :

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Sound localization is an important aspect of normal hearing. The Eph/ephin family of signaling proteins, studied here, is known to guide the formation of central auditory connections in early development, particularly topographic inputs from the lateral superior olive (LSO) to the inferior colliculus (IC). Processing in the LSO and its influences on the IC are known to be heavily involved in sound localization tasks. One way to study sound localization in mice is through pre-pulse inhibition (PPI). PPI is the phenomenon by which a weak prestimulus inhibits the response to a subsequent startle stimulus. In studying sound localization, the prestimulus here is a soft, ongoing sound that switches between two speakers 180 degrees apart. If the mouse hears a change in location, the acoustic startle response will decrease. Here we report three important considerations with this PPI speaker swap procedure. First, we show that the cage in which the mouse is tested is critically important. Depending on the testing chamber, we observed 17%, 33% and 100% of responsiveness noted in previously published studies. Second, homozygous but not heterozygous EphA4 mutations appear to affect sound localization. Finally, there appears to be subtle differences in startle responses for different mouse strains, with altered responses in both heterozygous and homozygous EphA4 mutants as compared with C57BL/6J controls. The connection between genetic effects on both afferent and efferent responsiveness may provide an experimental link between audiology and speech pathology, and thereby may serve as an animal model of altered central pattern generators.

Author: Jeffery A. Winer
Publisher: Springer Science & Business Media
ISBN: 0387270833
Category : Science
Languages : en
Pages : 720

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Connecting the auditory brain stem to sensory, motor, and limbic systems, the inferior colliculus is a critical midbrain station for auditory processing. Winer and Schreiner's The Inferior Colliculus, a critical, comprehensive reference, presents the current knowledge of the inferior colliculus from a variety of perspectives, including anatomical, physiological, developmental, neurochemical, biophysical, neuroethological and clinical vantage points. Written by leading researchers in the field, the book is an ideal introduction to the inferior colliculus and central auditory processing for clinicians, otolaryngologists, graduate and postgraduate research workers in the auditory and other sensory-motor systems.

Author: Pawel Strumillo
Publisher: BoD – Books on Demand
ISBN: 9533072245
Category : Technology & Engineering
Languages : en
Pages : 608

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Sound source localization is an important research field that has attracted researchers' efforts from many technical and biomedical sciences. Sound source localization (SSL) is defined as the determination of the direction from a receiver, but also includes the distance from it. Because of the wave nature of sound propagation, phenomena such as refraction, diffraction, diffusion, reflection, reverberation and interference occur. The wide spectrum of sound frequencies that range from infrasounds through acoustic sounds to ultrasounds, also introduces difficulties, as different spectrum components have different penetration properties through the medium. Consequently, SSL is a complex computation problem and development of robust sound localization techniques calls for different approaches, including multisensor schemes, null-steering beamforming and time-difference arrival techniques. The book offers a rich source of valuable material on advances on SSL techniques and their applications that should appeal to researches representing diverse engineering and scientific disciplines.

Author: John R. Smythies
Publisher: Academic Press
ISBN: 012404722X
Category : Medical
Languages : en
Pages : 408

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The present day is witnessing an explosion of our understanding of how the brain works at all levels, in which complexity is piled on complexity, and mechanisms of astonishing elegance are being continually discovered. This process is most developed in the major areas of the brain, such as the cortex, thalamus, and striatum. The Claustrum instead focuses on a small, remote, and, until recently, relatively unknown area of the brain. In recent years, researchers have come to believe that the claustrum is concerned with consciousness, a bold hypothesis supported by the claustrum's two-way connections with nearly every other region of the brain and its seeming involvement with multisensory integrations—the hallmark of consciousness. The claustrum, previously in a humble position at the back of the stage, might in fact be the conductor of the brain's orchestra. The Claustrum brings together leading experts on the claustrum from the varied disciplines of neuroscience, providing a state-of-the-art presentation of what is currently known about the claustrum, promising lines of current research (including epigenetics), and projections of new lines of investigation on the horizon. - Develops a unifying hypothesis about the claustrum's role in consciousness, as well as the integration of sensory information and other higher brain functions - Discusses the involvement of the claustrum with autism, schizophrenia, epilepsy, Alzheimer's disease, and Parkinson's disease - Coverage of all aspects of the claustrum, from its evolution and development to promising new lines of research, including epigenetics, provides a platform and point of reference for future investigative efforts

Author: Jan Schnupp
Publisher: MIT Press
ISBN: 0262518023
Category : Medical
Languages : en
Pages : 367

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An integrated overview of hearing and the interplay of physical, biological, and psychological processes underlying it. Every time we listen—to speech, to music, to footsteps approaching or retreating—our auditory perception is the result of a long chain of diverse and intricate processes that unfold within the source of the sound itself, in the air, in our ears, and, most of all, in our brains. Hearing is an "everyday miracle" that, despite its staggering complexity, seems effortless. This book offers an integrated account of hearing in terms of the neural processes that take place in different parts of the auditory system. Because hearing results from the interplay of so many physical, biological, and psychological processes, the book pulls together the different aspects of hearing—including acoustics, the mathematics of signal processing, the physiology of the ear and central auditory pathways, psychoacoustics, speech, and music—into a coherent whole.