[Novel analysis method to determine the neural activation function of the inner hair cell]

Sensorineural hearing loss (SNH) is one of the most common forms of hearing loss. A special form of SNH is hidden hearing loss (HHL) with subjective normal hearing. Current research results indicate that these patients demonstrate a reduced wave I in the averaged signal of brainstem audiometry (ABR). Since the averaging technique is not susceptible to latency jitter and amplitude height variation, a single sweep analysis is required for a deeper insight in HHL.

A total of 14 mice with significantly different calcium currents in the IHC at normal hearing thresholds were analysed. For the analysis in order to calculate four new parameters from the single sweeps in the time window of wave I. These parameters also served to describe a neural activation function (NAV).

Looking at the wild type all new parameters differ significantly or highly significantly. With the transgenic mouse, there are only non-significant to significant differences. There is also a significant difference in the neural activity demonstrated in the resting EEG between the wild-type mouse and the mutant. There is a negative correlation between the wave amplitudes for the wild mouse - after a strong amplitude follows a weak amplitude and after weak amplitude follows a strong amplitude.

Using new parameters based on single sweeps, surprising results are obtained. Obviously the function of the IHC correlates more strongly with the new parameters than it does with the average amplitude of wave I. The new parameters appear to be excellently suited for the diagnosis of hearing disorders even when hearing thresholds are still according to norm values.