Echoes of the spoken past: how auditory cortex hears context during speech perception.
What do we hear when someone speaks and what does auditory cortex (AC) do with that sound? Given how meaningful speech is, it might be hypothesized that AC is most active when other people talk so that their productions get decoded. Here, neuroimaging meta-analyses show the opposite: AC is least active and sometimes deactivated when participants listened to meaningful speech compared to less meaningful sounds. Results are explained by an active hypothesis-and-test mechanism where speech production (SP) regions are neurally re-used to predict auditory objects associated with available context. By this model, more AC activity for less meaningful sounds occurs because predictions are less successful from context, requiring further hypotheses be tested. This also explains the large overlap of AC co-activity for less meaningful sounds with meta-analyses of SP. An experiment showed a similar pattern of results for non-verbal context. Specifically, words produced less activity in AC and SP regions when preceded by co-speech gestures that visually described those words compared to those words without gestures. Results collectively suggest that what we 'hear' during real-world speech perception may come more from the brain than our ears and that the function of AC is to confirm or deny internal predictions about the identity of sounds.
['Skipper|Jeremy I|JI|']
D001303:Auditory Cortex D001307:Auditory Perception D001931:Brain Mapping D016208:Databases, Factual D005868:Gestures D006801:Humans D007802:Language D016013:Likelihood Functions D008959:Models, Neurological D008960:Models, Psychological D059906:Neuroimaging D013067:Speech Perception
auditory context predictive brain language multimodal