Journal Club

Giovanni will present Mégevand et al (2019), "Phase resetting in human auditory cortex to visual speech".

Natural conversation is multisensory: when we can see the speaker's face, visual speech cues influence our perception of what is being said. The neuronal basis of this phenomenon remains unclear, though there is indication that neuronal oscillations-ongoing excitability fluctuations of neuronal populations in the brain-represent a potential mechanism. Investigating this question with intracranial recordings in humans, we show that some sites in auditory cortex track the temporal dynamics of unisensory visual speech using the phase of their slow oscillations and phase-related modulations in neuronal activity. This effect is asymmetric, as we find much less detectable tracking of auditory speech by visual cortex. Auditory cortex thus builds a representation of the speech stream's envelope based on visual speech alone, at least in part by resetting the phase of its ongoing oscillations. Phase reset amplifies the representation of the speech stream and organizes the information contained in neuronal activity patterns.