Structures, Mechanisms, and Energetics in Temporal Processing

Brownell, William E.; Manis, Paul B.

doi:10.1007/978-1-4614-9102-6_2

Cited by 7 publications

(8 citation statements)

References 175 publications

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“…The spike time precision required to accomplish this does not require high levels of the low-voltage activated potassium channels. Employing lower channel densities may also reduce the energy requirements associated with a constant resting K + leakage through those channels (discussed in Brownell and Manis (2014)). On the other hand, animals with good low-frequency hearing such as gerbils and guinea pigs, will need to have higher densities of g KLT channels in order to minimize spike jitter, shorten refractory periods, and suppress supernumerary spikes (Gittelman and Tempel, 2006).…”

Section: Discussionmentioning

confidence: 99%

A biophysical modelling platform of the cochlear nucleus and other auditory circuits: From channels to networks

Manis

Campagnola

2018

Hearing Research

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Models of the auditory brainstem have been an invaluable tool for testing hypotheses about auditory information processing and for highlighting the most important gaps in the experimental literature. Due to the complexity of the auditory brainstem, and indeed most brain circuits, the dynamic behavior of the system may be difficult to predict without a detailed, biologically realistic computational model. Despite the sensitivity of models to their exact construction and parameters, most prior models of the cochlear nucleus have incorporated only a small subset of the known biological properties. This confounds the interpretation of modelling results and also limits the potential future uses of these models, which require a large effort to develop. To address these issues, we have developed a general purpose, biophysically detailed model of the cochlear nucleus for use both in testing hypotheses about cochlear nucleus function and also as an input to models of downstream auditory nuclei. The model implements conductance-based Hodgkin-Huxley representations of cells using a Python-based interface to the NEURON simulator. Our model incorporates most of the quantitatively characterized intrinsic cell properties, synaptic properties, and connectivity available in the literature, and also aims to reproduce the known response properties of the canonical cochlear nucleus cell types. Although we currently lack the empirical data to completely constrain this model, our intent is for the model to continue to incorporate new experimental results as they become available.

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Section: Discussionmentioning

confidence: 99%

A biophysical modelling platform of the cochlear nucleus and other auditory circuits: From channels to networks

Manis

Campagnola

2018

Hearing Research

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“…According to Brownell, the test-tube shaped OHC is a hydrostat [75]. At the same time, it is, according to another view [46], an exquisitely sensitive detector of minute pressure variations -that is, sound.…”

Section: Two Linked Hydrostats: the Labyrinth And The Outer Hair Cellmentioning

confidence: 99%

“…In a unique arrangement, the body of the OHC is surrounded on all sides by fluid, meaning that the OHC is in direct hydraulic communication with the stapes -that is, we have a hydrostat or pressure vessel surrounded on all sides by cochlear fluid. The OHC is piezoelectric and able to change length cycle by cycle, elongating and contracting in time with oscillating sound pressure [75]. Its outer walls are corrugated and are reinforced by helical fibres which encircle the cylindrical body in both clockwise and anticlockwise directions.…”

Section: Two Linked Hydrostats: the Labyrinth And The Outer Hair Cellmentioning

confidence: 99%

Middle Ear Muscle Dysfunction as The Cause of Meniere’s Disease

Bell¹

2017

J Hear Sci

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The symptoms of Meniere's disease form a distinct cluster: bouts of vertigo, fluctuating hearing loss, low-frequency tinnitus, and a feeling of pressure in the ear. Traditionally, these signature symptoms have pointed to some sort of pathology within the inner ear itself, but here the focus is shifted to the middle ear muscles. These muscles, the tensor tympani and the stapedius, have generally been seen as serving only a secondary protective role in hearing, but in this paper they are identified as vigilant gate-keepers -constantly monitoring acoustic input and dynamically adjusting hearing sensitivity so as to enhance external sounds and suppress internally generated ones. The case is made that this split-second adjustment is accomplished by regulation of inner ear pressure: when the middle ear muscles contract they push the stapes into the oval window and increase the pressure of fluids inside the otic capsule. In turn, hydraulic pressure squeezes hair cells, instantly adjusting their sensitivity. If the middle ear muscles should malfunction -such as from cramp, spasm, or dystonia -the resulting abnormal pressure will disrupt hair cells and produce Meniere's symptoms.A wide-ranging review of Meniere's disease and the middle ear muscles reinforces the link between the two. Since every striated muscle is prone to dystonia -an involuntary contraction involving derangement of its underlying control loop -middle ear muscle dystonia would lead to elevated pressure and abnormal hair cell function. The hypothesis is based on recognizing that the inner ear is a hydrostat -a cavity filled with fluid whose pressure is controlled by the middle ear muscles. Since the fluid is incompressible, even a slight contraction of the muscles can increase the pressure in the labyrinth to 3 kPa. The effect of such a pressure on the sensing cells within is crucial. Outer hair cells carry an internal turgor pressure of about 1 kPa, behaving physically like inflated balloons, and hence contraction of the middle ear muscles can instantly overcome internal cellular pressure, switch off ion channels, and reduce hearing sensitivity. This paper brings together supporting evidence and sets out major implications for Meniere's disease, including possible treatments.

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“…We called this standing current the silent current because it is functionally similar to the dark current in the retina. The high conductance ion channels found in both cell types (for review see Brownell and Manis [7]) result in large currents that place energetic demands on the ear and auditory neurons. The currents are regulated by similar membrane proteins that have a shallow, variable voltage dependence promoting a broad dynamic range and further increasing metabolic demand.…”

Section: Fast Temporal Processing Requires Short Electrical Time Consmentioning

confidence: 99%

“…Imaging studies similar to those that reveal the metabolic activity of the stria vascularis show auditory brainstem nuclei to be among the most metabolically active structures in the brain. The enrichment of mitochondria in the short stubby dendrites of bushy cells argue for standing currents (most likely dominated by potassium ions) from the dendrites through the soma to the axons [7].…”

Section: Fast Temporal Processing Requires Short Electrical Time Consmentioning

confidence: 99%

The neuromechanics of hearing

Araya¹,

Brownell²

2015

AIP Conference Proceedings

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The relation between tympanic membrane higher order modes and standing waves AIP Conference Proceedings 1703, 060008 (2015) Abstract. Hearing requires precise detection and coding of acoustic signals by the inner ear and equally precise communication of the information through the auditory brainstem. A membrane based motor in the outer hair cell lateral wall contributes to the transformation of sound into a precise neural code. Structural, molecular and energetic similarities between the outer hair cell and auditory brainstem neurons suggest that a similar membrane based motor may contribute to signal processing in the auditory CNS. Cooperative activation of voltage gated ion channels enhances neuronal temporal processing and increases the upper frequency limit for phase locking. We explore the possibility that membrane mechanics contribute to ion channel cooperativity as a consequence of the nearly instantaneous speed of electromechanical signaling and the fact that membrane composition and mechanics modulate ion channel function.

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Structures, Mechanisms, and Energetics in Temporal Processing

Cited by 7 publications

References 175 publications

A biophysical modelling platform of the cochlear nucleus and other auditory circuits: From channels to networks

A biophysical modelling platform of the cochlear nucleus and other auditory circuits: From channels to networks

Middle Ear Muscle Dysfunction as The Cause of Meniere’s Disease

The neuromechanics of hearing

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