The effects of temperature change and transient hypoxia on auditory nerve fiber response in the goldfish (Carassius auratus).

Temperature change and hypoxia produce consistent, reversible effects on the response of single auditory nerve fibers in the goldfish. Cooling and hypoxia produce reductions of a cell's spontaneous activity, sensitivity, most excitatory or best frequency (BF) at a given signal level, and overall responsiveness to acoustic stimulation. Warming above ambient temperatures increases a cell's spontaneous activity, sensitivity, BF, and responsiveness. Adaptation, or the tendency for responsiveness to decline with time during a stimulus, increases during hypoxia and cooling, and decreases during warming. The effects of temperature change and hypoxia on a fiber's BF are similar to the effects of overall sound level. Since BF normally increases with sound level, the BF-shift with temperature change and hypoxia can be understood as a change in sensitivity or the overall effectiveness of a stimulus at a given sound level. The effects on neural response of temperature change and hypoxia are probably due in part to changes in the release and replenishment of neurotransmitter at the synapses between hair cells and auditory nerve fibers.