Simulation of mechanical to neural transduction in the auditory receptor

Abstract

A probabilistic model is described for transmitter release from hair cells, auditory neuron EPSP's, and discharge patterns. The model assumes that the release fraction of the transmitter is a function of stimulus intensity. It further assumes that some of this transmitter substance is taken back into the cell while some is irretrievably lost from the cleft. These assumptions differ from other recent models which propose multiple release sites, fixed release fractions, and no transmitter reuptake. The model produces realistic mammalian rate intensity functions, interval and period histograms, incremental responses, and adaptation effects. It mimics successfully the adaptation of successive EPSP amplitudes of the afferent neuron of the goldfish sacculus and offers a reinterpretation of the implications of these studies for hair cell synaptic mechanism.

Electrical Excitation of the Acoustically Sensitive Auditory Nerve: Single-Fiber Responses to Electric Pulse Trains

“…10 and 12), something not observed with acoustic stimulation. Javel (1990) noted that adaptation to electric stimuli calls for a reevaluation of the mechanisms of adaptation, which is often solely attributed to the hair cell and synapse (e.g., Smith and Brachman 1982;Meddis 1986). One approach to this issue would be to compare acoustic and electric adaptation as functions of instantaneous, or short-term, response rates.…”

A phenomenological model of the synapse between the inner hair cell and auditory nerve: Long-term adaptation with power-law dynamics

“…Although the mechanism that gives rise to synaptic adaptation is not completely understood, it could be caused either by the depletion of neurotransmitter from a readily releasable presynaptic pool of neurotransmitter ͑Moser and Beutner, 2000; Schnee et al, 2005;Goutman and Glowatzki, 2007͒ or by the desensitization of post-synaptic receptors ͑Raman et al, 1994͒. Modeling the adaptation in the IHC-AN synapse has been a focus of extensive research over the last several decades. Early attempts employed a single-reservoir system with loss and replenishment of transmitter quanta ͑Schroeder and Hall, 1974;Sujaku, 1974, 1975͒, and later models added extra reservoirs ͑or sites͒ or more complex principles of transmitter flow control ͑Furukawa and Matsuura, 1978;Furukawa et al, 1982;Ross, 1982Ross, , 1996Schwid and Geisler, 1982;Smith and Brachman, 1982;Cooke, 1986;Meddis, 1986Meddis, , 1988Westerman and Smith, 1988͒. In general, the transmitter in these models lies in reservoirs or sites close to the presynaptic membrane and diffuses between reservoirs within the cell and out of the cell to the synaptic cleft.…”

“…The diversity and complexity of adaptation pose a great challenge for successful modeling of the dynamics of this synapse. Two models with different structures have been developed independently in a series of studies ͑Meddis, 1986͑Meddis, , 1988Westerman and Smith, 1988;Carney, 1993;Zhang et al, 2001;Sumner et al, 2002. However, the mathematical descriptions of these two models are essentially equivalent despite their structural differences ͑Zhang and Carney, 2005͒.…”

A Functional Point-Neuron Model Simulating Cochlear Nucleus Ideal Onset Responses

“…The output of each gammatone filter serves as input to Meddis' model of the mechanical to neural transduction at the hair cell-auditory nerve synapse (Meddis, 1986(Meddis, , 1988Meddis et al, 1990). The output is the instantaneous AN discharge rate function in response to arbitrary stimuli.…”

“…In the peripheral stage of the present model, the mechanical to neural transduction at the hair cell-auditory nerve synapse was simulated using Meddis' model implementation (Meddis, 1986(Meddis, , 1988Meddis et al, 1990). Instead of actually computing individual spike trains for each AN fiber the "deterministic" rate function at the output of the synapse was considered as representing the AN activity.…”