Central conduction time in auditory brainstem response and ear advantage in dichotic listening across menstrual cycle.

Chi-Chuen Lau,Xu-Jun Hu

doi:10.1371/journal.pone.0187672

Chi-Chuen Lau, Xu-Jun Hu

Open Access

https://doi.org/10.1371/journal.pone.0187672

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Abstract

The ovarian hormones fluctuate during the menstrual cycle in women. Such fluctuation of sex hormones, in particular estrogen, is believed to affect the central conduction time in auditory function as well as the language lateralization in cognitive function. However, findings are inconsistent. The underlying mechanisms are also unclear. This paper examined if there was any relation between the central conduction time and the language lateralization at different times during the menstrual cycle. Twenty young women with normal menstrual cycle were tested four times (5 to 7 days apart) across the menstrual cycle. The test battery included the electrophysiological measurement of auditory evoked response in brainstem and the speech performance in dichotic listening with monosyllables as stimulus pairs. The dichotic listening task was conducted under the non-forced, forced-right and forced-left attention. The central conduction time was defined by the time elapsed between two auditory elicited responses along the auditory pathway. The language lateralization in dichotic listening was expressed in ear advantage, which was the right-ear score minus the left-ear score. The results showed that the effects of test time were significant on both the central conduction time and the ear advantage under the forced-left attention. Overall, the interaural difference in the central conduction time correlates with the ear advantage (non-forced attention) at the beginning of the menstrual cycle. The change in central conduction time between two test times correlates significantly with the change in ear advantage under the non-forced and forced-left attention. Conclusively, the central conduction time depends on the time during the menstrual cycle, which in turn may affect the performance in dichotic listening.

Highlights

The sex hormones in females, primarily estrogen and progesterone, fluctuate during the menstrual cycle [1]
Central conduction time and ear advantage across menstrual cycle and the language lateralization as measured in the dichotic listening task [3]
The wave latency for peak V is longest at the 2nd test time, while the interpeak conduction time is highest at this test time for the interpeaks III-V and I-V

Summary

Introduction

The sex hormones in females, primarily estrogen and progesterone, fluctuate during the menstrual cycle [1]. The auditory brainstem response (ABR) is a tool commonly used to examine the effect of the menstrual cycle on auditory function [4]. ABR is a far-field electrical recording of the neuron activities in brainstem during the processing of sound transmitted from an acoustic transducer such as an insert earphone. When the acoustic signal travels along the auditory pathway from the cochlear nuclear complex to the inferior colliculus, it elicits a series of neuron activities at certain sites. The evoked neuron activities can be measured electrically as peaks and troughs by the surface electrodes typically placed at the vertex of the scalp and the ear lobes. Two measurements are typically used in research: the time elapsed (i.e., wave latency) for a peak action potential to occur and the interpeak conduction time for the signal to travel between two major neuron sites [5]. The peaks in the waveform normally occur within the first 10 ms after a click or tone-burst stimulus has been presented at 70–90 dB nHL

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