Hair cell ribbon synapses

Moser, Tobias; Brandt, Andreas; Lysakowski, Anna

doi:10.1007/s00441-006-0276-3

Cited by 146 publications

(133 citation statements)

References 111 publications

(159 reference statements)

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“…Hair cells are also presynaptic terminals, the basolateral membrane of each cell contains several presynaptic actives zones, where chemical neurotransmitter is released. In mammals, 5-30 auditory fibers contacts one inner hair cell trough a single unbranched dendrite, in a single ribbon synapses (Moser et al, 2006). The probability of a spike occurring in a fiber is directly proportional to the concentration of neurotransmitter in the synaptic cleft (Carney, 1993).…”

Section: Auditory Peripherymentioning

confidence: 99%

A biophysical model for modulation frequency encoding in the cochlear nucleus

Eguía

García

Romano

2010

Journal of Physiology-Paris

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a b s t r a c tEncoding of amplitude modulated (AM) acoustical signals is one of the most compelling tasks for the mammalian auditory system: environmental sounds, after being filtered and transduced by the cochlea, become narrowband AM signals. Despite much experimental work dedicated to the comprehension of auditory system extraction and encoding of AM information, the neural mechanisms underlying this remarkable feature are far from being understood (Joris et al., 2004). One of the most accepted theories for this processing is the existence of a periodotopic organization (based on temporal information) across the more studied tonotopic axis (Frisina et al., 1990b).In this work, we will review some recent advances in the study of the mechanisms involved in neural processing of AM sounds, and propose an integrated model that runs from the external ear, through the cochlea and the auditory nerve, up to a sub-circuit of the cochlear nucleus (the first processing unit in the central auditory system). We will show that varying the amount of inhibition in our model we can obtain a range of best modulation frequencies (BMF) in some principal cells of the cochlear nucleus. This could be a basis for a, synchronicity based, low-level periodotopic organization.

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Section: Auditory Peripherymentioning

confidence: 99%

A biophysical model for modulation frequency encoding in the cochlear nucleus

Eguía

García

Romano

2010

Journal of Physiology-Paris

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“…The ribbons of mammalian rods wrap around the synaptic ridge to create a distinctive crescent or horseshoe shape [63]. Synaptic ribbons with different shapes but similar molecular features are found in other sensory neurons including hair cells and retinal bipolar cells [4,5,[64][65][66][67].…”

Section: Anatomical Features Of the Photoreceptor Synapsementioning

confidence: 99%

Kinetics of Synaptic Transmission at Ribbon Synapses of Rods and Cones

Thoreson

2007

Mol Neurobiol

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The ribbon synapse is a specialized structure that allows photoreceptors to sustain the continuous release of vesicles for hours upon hours and years upon years but also respond rapidly to momentary changes in illumination. Light responses of cones are faster than those of rods and, mirroring this difference, synaptic transmission from cones is also faster than transmission from rods. This review evaluates the various factors that regulate synaptic kinetics and contribute to kinetic differences between rod and cone synapses. Presynaptically, the release of glutamate-laden synaptic vesicles is regulated by properties of the synaptic proteins involved in exocytosis, influx of calcium through calcium channels, calcium release from intracellular stores, diffusion of calcium to the release site, calcium buffering, and extrusion of calcium from the cytoplasm. The rate of vesicle replenishment also limits the ability of the synapse to follow changes in release. Post-synaptic factors include properties of glutamate receptors, dynamics of glutamate diffusion through the cleft, and glutamate uptake by glutamate transporters. Thus, multiple synaptic mechanisms help to shape the responses of second-order horizontal and bipolar cells. KeywordsPhotoreceptor; Synaptic transmission; Glutamate; Calcium; Vesicles; Retina Vision begins with the transduction of light into membrane potential changes as the result of an enzymatic cascade occurring in the outer segments of rod and cone photoreceptors [1,2]. Light-evoked membrane potential changes are modified by voltage-dependent currents in the inner segment [3] and transmitted to second order bipolar and horizontal cells by changes in release of the neurotransmitter, L-glutamate, from the synaptic terminals of both rods and cones. Because all of the visual information available to downstream retinal neurons must first pass through the photoreceptor synapse, synaptic transmission from photoreceptors has a considerable impact on visual perception. The focus of this review is on mechanisms that shape the kinetics of synaptic transmission at synapses of rods and cones. Additional information on other physiological and anatomical characteristics of photoreceptor ribbon synapses can be found in recent reviews [4][5][6]. Differences in Rod and Cone KineticsRod and cone photoreceptors are tonically depolarized in darkness with membrane potentials of −35 to −45 mV that allow continuous release of the neurotransmitter, L-glutamate. Light onset causes photoreceptors to hyperpolarize by as much as 30 mV, leading to a reduction in

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“…A thorough understanding of ANF response properties is therefore crucial for understanding the auditory system as a whole. In mammals, each ANF is excited via a single ribbon synapse in a single receptor cell, the inner hair cell (IHC) (Liberman et al, 1990), and ANF responses therefore also provide insights into the operation of these intriguing synapses (for review, see Fuchs, 2005;Moser et al, 2006;Nouvian et al, 2006;Matthews and Fuchs, 2010).…”

Section: Introductionmentioning

confidence: 99%

An Improved Model for the Rate–Level Functions of Auditory-Nerve Fibers

Heil

Neubauer

Irvine³

2011

J. Neurosci.

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Acoustic information is conveyed to the brain by the spike patterns in auditory-nerve fibers (ANFs). In mammals, each ANF is excited via a single ribbon synapse in a single inner hair cell (IHC), and the spike patterns therefore also provide valuable information about those intriguing synapses. Here we reexamine and model a key property of ANFs, the dependence of their spike rates on the sound pressure level of acoustic stimuli (rate-level functions). We build upon the seminal model of Sachs and Abbas (1974), which provides good fits to experimental data but has limited utility for defining physiological mechanisms. We present an improved, physiologically plausible model according to which the spike rate follows a Hill equation and spontaneous activity and its experimentally observed tight correlation with ANF sensitivity are emergent properties. We apply it to 156 cat ANF rate-level functions using frequencies where the mechanics are linear and find that a single Hill coefficient of 3 can account for the population of functions. We also demonstrate a tight correspondence between ANF rate-level functions and the Ca 2ϩ dependence of exocytosis from IHCs, and derive estimates of the effective intracellular Ca 2ϩ concentrations at the individual active zones of IHCs. We argue that the Hill coefficient might reflect the intrinsic, biochemical Ca 2ϩ cooperativity of the Ca 2ϩ sensor involved in exocytosis from the IHC. The model also links ANF properties with properties of psychophysical absolute thresholds.

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Hair cell ribbon synapses

Cited by 146 publications

References 111 publications

A biophysical model for modulation frequency encoding in the cochlear nucleus

A biophysical model for modulation frequency encoding in the cochlear nucleus

Kinetics of Synaptic Transmission at Ribbon Synapses of Rods and Cones

An Improved Model for the Rate–Level Functions of Auditory-Nerve Fibers

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