Human iEEG recordings during audiovisual speech violations support and extend predictive routing models

In superior temporal cortex of seven presurgical epilepsy patients, audiovisual speech violations linked to the McGurk condition increase high-gamma and decrease alpha-beta power.

• Why it matters: Predictive processing and predictive routing propose that alpha-beta rhythms suppress gamma when inputs match predictions, but human iEEG evidence for this mechanism is incomplete.
• What they did: Using intracranial EEG across superior temporal and frontal/premotor areas, the study computed theta, alpha-beta, and high-gamma power during auditory deviance, multisensory integration, and audiovisual incongruence.
• The result: High-gamma shows a prediction-error signal in superior temporal cortex for auditory deviance and McGurk, whereas frontal areas lack this high-gamma effect and instead show theta-linked prediction error.

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