Abstract
Neural oscillation is attracting attention as an underlying mechanism for speech recognition. Speech intelligibility is enhanced by the synchronization of speech rhythms and slow neural oscillation, which is typically observed as human scalp electroencephalography (EEG). In addition to the effect of neural oscillation, it has been proposed that speech recognition is enhanced by the identification of a speaker’s motor signals, which are used for speech production. To verify the relationship between the effect of neural oscillation and motor cortical activity, we measured scalp EEG, and simultaneous EEG and functional magnetic resonance imaging (fMRI) during a speech recognition task in which participants were required to recognize spoken words embedded in noise sound. We proposed an index to quantitatively evaluate the EEG phase effect on behavioral performance. The results showed that the delta and theta EEG phase before speech inputs modulated the participant’s response time when conducting speech recognition tasks. The simultaneous EEG-fMRI experiment showed that slow EEG activity was correlated with motor cortical activity. These results suggested that the effect of the slow oscillatory phase was associated with the activity of the motor cortex during speech recognition.
Highlights
Neural oscillations are attracting attention as underlying mechanisms of perceptual and cognitive abilities
To test whether behavioral performance in speech recognition changed based on the ongoing EEG phase, we evaluated the relationship between the accuracy, reaction time and EEG phase by using the proposed phaseutility on behavior (PUB) index
We evaluated the correlation between the phase of ongoing EEG activity and behavioral performance using the PUB analysis
Summary
Neural oscillations are attracting attention as underlying mechanisms of perceptual and cognitive abilities. Neural oscillation is a rhythmic neural activity that can be observed through EEG recordings. Recent studies have shown that cortical neural excitability depends on the phase of ongoing neural oscillations in sound detection tasks [1,2,3]. Neural excitability could modulate perceptual performance in visual or auditory processing [4,5,6,7]. For auditory perception, the phase of slow oscillations (delta or theta activities) modulated behavioral performance in scalp EEG studies [4, 5]. Neural oscillation is an important activity that mediates the process of effective auditory perception
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