Conservation of adapting components in auditory-nerve responses

Abstract

The responses of single auditory-nerve fibers of Mongolian gerbil were studied using tonal stimuli. The peristimulatory adaptation of firing rate in response to tone bursts presented in quiet and during a background stimulus is described quantitatively. The total transient response which can be produced to the onset of a tone burst, whether presented in quiet or as an intensity increment, is limited and appears to demonstrate a form of conservation. Specifically, the total numbers of spikes produced by the rapidly adapting component, and the slower short-term adaptation component, are proportional at all intensities, and are limited for each fiber. Furthermore, when an incremental stimulus is presented on a background, the total transient response to the background and to the increment is limited and depends upon the final intensity, not the background intensity. When the presumed underlying synaptic drive is derived by removing the effects of refractoriness from the spike train, the same conservation of the transient response components, and proportionality between rapid and short-term components, are observed.

Noise-induced hearing loss alters the temporal dynamics of auditory-nerve responses

“…However, a handful of AN fibers (n = 21 / 305, mostly with CFs<750 Hz) had fits with time constants below 1 ms. These values were below the PST bin width as well as the lower limits of adaptation time constants previously reported in the literature (e.g., Westerman and Smith, 1987). Typically when longer duration stimuli have been used, rapid time constants on the order of 3–4 ms and short term time constants on the order of 60 ms have been reported.…”

Adaptation in the auditory system: an overview

“…In these neurons, it was possible to use a binaural stimulation paradigm that allowed separation of the adaptation of the binaural neurons from that happening at lower monaural levels, such as the auditory nerve fibers. This study revealed that these IC neurons had adaptation dynamics that were rather slow, compared with those calculated for the auditory nerve fibers (Yates et al, 1983, 1985; Westerman and Smith, 1987). The different time constants indicate that the adaptation found in the IC is different from that found in the auditory nerve, and moreover, it is not just inherited from the lower levels.…”

“…One possible role for adaptation in the auditory system lies in determining the sensitivity of auditory neurons to the stimulus context. The rapid adaptation in auditory nerve fiber responses (Yates et al, 1985; Westerman and Smith, 1987), and the rapid recovery from adaptation (Yates et al, 1983), suggests that the time course of adaptation in the peripheral nerve fibers might dominate the time course of adaptation in higher centers, unless it is somehow filtered out by neurons at subsequent stages. Indeed, adaptation in these early stages of the auditory pathway may have important implications in the processing of auditory cues at higher centers.…”

Influence of cochlear traveling wave and neural adaptation on auditory brainstem responses

“…The change in neural activity is typically maximum at onset and then decays or adapts to a smaller sustained change in response. The neural mechanisms underlying adaptation have been studied in peripheral and more central stages of the auditory nervous system (e.g., Smith, 1977;Kramer and Teas, 1982;Westerman and Smith, 1987;Arehole et al, 1989;Kaltenbach et al, 1993). At the level of the auditory nerve, adaptation can be described using two time constants: "rapid", which occurs over 1-10 ms, and "short-term" in which the time constant is approx.…”