Sex differences in early sensorimotor processing for speech discrimination

David Thornton,Ashley W. Harkrider,David E. Jenson,Tim Saltuklaroglu

doi:10.1038/s41598-018-36775-5

Abstract

Sensorimotor activity in speech perception tasks varies as a function of context, cognitive load, and cognitive ability. This study investigated listener sex as an additional variable. Raw EEG data were collected as 21 males and 21 females discriminated /ba/ and /da/ in quiet and noisy backgrounds. Independent component analyses of data from accurately discriminated trials identified sensorimotor mu components with characteristic alpha and beta peaks from 16 members of each sex. Time-frequency decompositions showed that in quiet discrimination, females displayed stronger early mu-alpha synchronization, whereas males showed stronger mu-beta desynchronization. Findings indicate that early attentional mechanisms for speech discrimination were characterized by sensorimotor inhibition in females and predictive sensorimotor activation in males. Both sexes showed stronger early sensorimotor inhibition in noisy discrimination conditions versus in quiet, suggesting sensory gating of the noise. However, the difference in neural activation between quiet and noisy conditions was greater in males than females. Though sex differences appear unrelated to behavioral accuracy, they suggest that males and females exhibit early sensorimotor processing for speech discrimination that is fundamentally different, yet similarly adaptable to adverse conditions. Findings have implications for understanding variability in neuroimaging data and the male prevalence in various neurodevelopmental disorders with inhibitory dysfunction.

Highlights

Sensorimotor activity in speech perception tasks varies as a function of context, cognitive load, and cognitive ability
Alpha bands are well known for producing patterns of both event-related desynchronization (ERD) and synchronization (ERS); depicting evidence of both cortical activation and inhibition, respectively[30,31]
All tasks produced over 86% accuracy in participants who contributed to mu clusters, with no significant differences in either test condition between males and females (QD: F(1, 30) = 0.153, p = 0.698, noisy background (ND): F(1,30) = 0.038, p = 0.847)

Summary

Introduction

Sensorimotor activity in speech perception tasks varies as a function of context, cognitive load, and cognitive ability. Electroencephalography (EEG) offers strong temporal resolution for precisely capturing event-related changes in neural activity across the time course of speech perception tasks Power in both alpha (8–13 Hz) and beta (15–25 Hz) rhythms is sensitive to capturing sensorimotor function[28,29] across the time course of a perception event, including early attentional and later working memory processes. In a number of tasks with both cognitive and motor components, time-frequency decompositions of EEG data reveal sex-based differences in alpha and beta (in addition to theta) rhythm activity recorded across frontal and central electrodes[45]. Along with previous evidence of sex differences in behavioral and neural responses during the performance of cognitive and linguistic tasks, the data from the Jenson et al.[43] and Saltuklaroglu et al.[47] provide some support for mu rhythm oscillations being sensitive to sexual dimorphism in speech discrimination and additional impetus for the current examination

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