Further studies on the Schroeder–Hall hair-cell model

One class of models of hair cell synaptic function that has been investigated in recent years consists of one or more reservoirs of synaptic material connected to other reservoirs and/or the synaptic cleft by means of diffusion paths. One such general model is considered here, comprising two reservoirs and a global source of synaptic material connected in series and releasing material into the synaptic cleft by a diffusion path characterized by an intensity-dependent permeability. The explicit form of the solution of the model for a sudden onset of stimulation is derived: The solution comprises two exponentially decaying terms plus a constant. This solution is shown to have a unique inverse. This allows the determination of the parameters of the model directly from experimental data from auditory-nerve fibers in the Mongolian gerbil. The behavior of the derived model parameters with variation of stimulus intensity is demonstrated, and implications for synaptic function are discussed.

Section: Application Of These Modeling Results To Comparable Singlefimentioning

confidence: 99%

A diffusion model of the transient response of the cochlear inner hair cell synapse

Westerman¹,

Smith

1988

“…Our model differs somewhat from earlier mathematical descriptions of input-output relationships (e.g., Weiss, 1966;Zwislocki, 1973), and its behavior is comparable to the input-output behavior of Schroeder and Hall's (1974) hair cell model (see also Geisler et al, 1979). We developed this model for two reasons: First, we wanted to describe input-output functions more accurately at near-threshold intensities than was possible with earlier models.…”

Section: B Excitation Threshold Versus Suppression Thresholdmentioning

confidence: 95%

Suppression of auditory nerve responses. II. Suppression threshold and growth, iso-suppression contours

Javel

McGee

Walsh

et al. 1983

Two-tone "synchrony suppression" was studied in responses of single auditory nerve fibers recorded from anesthetized cats. Suppression thresholds for suppressor tones set to a fiber's characteristic frequency (CF) were approximately equal to discharge rate thresholds for CF tones. Suppression thresholds above and below CF were usually lower than the corresponding discharge rate thresholds. However, at all frequencies studied (including CF), suppression thresholds were higher than the corresponding thresholds for discharge synchronization. Across fibers, rates of suppression growth for suppressors at CF were greatest in low-CF fibers and least in high-CF fibers, and there was a systematic decrease in suppression growth rate at CF as CF increased. Within fibers, rates of suppression growth above CF were typically less than at CF, and slopes were monotonically decreasing functions of frequency. Within-fiber rates of suppression growth below CF were variable, but they usually were greater than rates of growth at CF. Iso-suppression contours (frequencies and intensities producing criterion amounts of suppression) indicated that tones near CF are the most potent suppressors at near-threshold intensities, and that the frequency producing the most suppression usually shifts downward as the amount of suppression increases. These data support the notion that synchrony suppression arises primarily as a passive consequence of hair cell activation.

“…In recent years, a number of increasingly sophisticated computational models of this process have been presented that aim to explain the particular nonlinearities that occur at the junction between the inner hair cells and individual auditory-nerve fibers, the point of neuromechanical transduction (Siebert, 1965;Weiss, 1966;Nilsson, 1975;Schroeder and Hall, 1974;Oono and Sujaku, 1975;Eggermont, 1973;Geisler et al, 1979;Brachman, 1980;Ross, 1982;Schwid and Geisler, 1982;Smith and Brachman, 1982;Westerman, 1985;Westerman and Smith, 1986;Cooke, 1986;Meddis, 1986).…”

Section: Introductionmentioning

confidence: 99%

Simulation of auditory–neural transduction: Further studies

Meddis

1988

211

100

A computational model of mechanical to neural transduction at the hair cell-auditory-nerve synapse is presented. It produces a stream of events (spikes) that are precisely located in time in response to an arbitrary stimulus and is intended for use as an input to automatic speech recognition systems as well as a contribution to the theory of the origin of auditory-nerve spike activity. The behavior of the model is compared to data from animal studies in the following tests: (a) rate-intensity functions for adapted and unadapted responding; (b) two-component short-term adaptation; (c) frequency-limited phase locking of events; (d) additivity of responding following stimulus-intensity increases and decreases; (e) recovery of spontaneous activity following stimulus offset; and (f) recovery of ability to respond to a second stimulus following offset of a first stimulus. The behavior of the model compares well with empirical data but discrepancies in tests (d) and (f) point to the need for further development. Additional functions that have been successfully simulated in previous tests include realistic interspike-interval histograms for silence and intense sinusoidal stimuli, realistic poststimulus period histograms at various intensities and nonmonotonic functions relating incremental and decremental responses to background stimulus intensity. The model is computationally convenient and well suited to use in automatic recognition devices that use models of the peripheral auditory system as input devices. It is particularly well suited to devices that require stimulus phase information to be preserved at low frequencies.