| Abstrakt: |
In response to changes in sound intensity, auditory-nerve fibers appear to exhibit both rapid and short-term adaptation. The former produces a rapid change in firing rate during the first few milliseconds of response, while the latter causes a change over tens of milliseconds. Both processes have similar effects on the shape of PST histograms. However, they differ in the quantitative relationship they produce between onset and steady-state responses [R. L. Smith and M. L. Brachman, Brain Res. 184, 499-505 (1980)] and in the way they are influenced by prior adaptation [M. L. Brachman et al., J. Acoust. Soc. Am. Suppl. 1 65, S83 (1979)]. A phenomenological model has been developed to account for the experimental results. According to the model, rapid adaptation reflects the depletion of a substance, possibly synaptic transmitter. The substance is stored in a group of mutually independent regions, and flow from a given region occurs only when stimulus intensity exceeds an appropriate level. Substance is replenished from a more slowly depleted reservoir which produces short-term adaptation. The reservoir is replenished from a fixed concentration which determines the steady-state response. [Work supported by NSF and NIH.] [ABSTRACT FROM AUTHOR] |
