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Neural alpha oscillations index context-driven perception of ambiguous vowel sequences
Claude Alain1,2, Katharina Göke1, Dawei Shen1
1Rotman Research Institute, Toronto, ON M6A 2E1, Canada.
Iscience
|December 7, 2023
Summary
Prior auditory context influences perception. Listeners often perceive the opposite of the immediately preceding sound, a contrast effect linked to neural adaptation in auditory brain regions.
Area of Science:
- Auditory Neuroscience
- Perceptual Psychology
- Cognitive Neuroscience
Background:
- Perception of ambiguous stimuli is known to be influenced by preceding context.
- This influence can manifest as either assimilation (matching the prior percept) or contrast (opposite of the prior percept).
Purpose of the Study:
- To investigate the neural mechanisms underlying the auditory contrast effect for bistable vowel stimuli.
- To determine if specific brain regions and their activity patterns correlate with this perceptual phenomenon.
Main Methods:
- High-density electroencephalography (EEG) was used to record brain activity.
- Participants listened to sequences of vowel sounds with varying formant transitions, including a final ambiguous bistable sequence.
- Behavioral reports of auditory perception were collected alongside EEG data.
Main Results:
- Participants showed a significant tendency to perceive the opposite of the immediately preceding vowel percept (auditory contrast effect).
- This contrast effect was associated with changes in alpha power in specific brain areas, including the left angular gyrus and bilateral sensorimotor/supramarginal regions.
- Activity in the sensorimotor/supramarginal areas correlated with individual participants' perceptual reports.
Conclusions:
- The auditory contrast effect for bistable vowel sequences appears to be mediated by neural adaptation in posterior auditory areas.
- These adaptive changes influence how ambiguous auditory stimuli are interpreted, affecting perceptual construal.
- The findings highlight the role of context-dependent neural processes in shaping auditory perception.
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