title: Induced neural beta oscillations predict categorical speech perception abilities.
abstract: Neural oscillations have been linked to various perceptual and cognitive brain operations. Here, we examined the role of these induced brain responses in categorical speech perception (CP), a phenomenon in which similar features are mapped to discrete, common identities despite their equidistant/continuous physical spacing. We recorded neuroelectric activity while participants rapidly classified sounds along a vowel continuum (/u/ to /a/). Time-frequency analyses applied to the EEG revealed distinct temporal dynamics in induced (non-phase locked) oscillations; increased β (15-30Hz) coded prototypical vowel sounds carrying well-defined phonetic categories whereas increased γ (50-70Hz) accompanied ambiguous tokens near the categorical boundary. Notably, changes in β activity were strongly correlated with the slope of listeners' psychometric identification functions, a measure of the "steepness" of their categorical percept. Our findings demonstrate that in addition to previously observed evoked (phase-locked) correlates of CP, induced brain activity in the β-band codes the ambiguity and strength of categorical speech percepts.
authors.affiliation: Institute for Intelligent Systems, University of Memphis, Memphis, TN, USA; School of Communication Sciences & Disorders, University of Memphis, Memphis, TN, USA. Electronic address: g.bidelman@memphis.edu.
authors.forename: Gavin M
authors.initials: GM
authors.lastname: Bidelman
mesh_terms: D000328:Adult; D001611:Beta Rhythm; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D005260:Female; D065818:Gamma Rhythm; D006801:Humans; D008297:Male; D010700:Phonetics; D013067:Speech Perception
keywords: Beta activity; Categorical speech perception; EEG; Gamma activity; Induced brain responses; Neural oscillations; Time–frequency analysis