Understanding Intentions of Others Reflects Evoked Responses in the Human Mirror Neuron System: Evidence From Combined fMRI and EEG Repetition Suppression

摘要

Viewing the behavior of other agents to infer and understand their intents recruits brain regions within the mirror neuron system (MNS), particularly the inferior parietal lobule and inferior frontal gyrus. However, decoding when intention understanding occurs in the human brain remains unclear. Accordingly, and to distinguish MNS involvement from lower level visual scene analysis, we tested repetition suppression effects in 24 healthy male volunteers who performed an intention inference task while their brain activity was recorded with high-spatial fMRI and high-temporal EEG recordings. During this intention inference task, participants were instructed to attend to video-clips displaying hand-on object actions, and to try to decode 'why' actions were being performed. Functional MRI results confirmed the specific role of the MNS and superior temporal sulcus (STS) in intention understanding by revealing repetition suppressions (RS) in inferior parietal, inferior frontal cortex, and STS when participants saw repeated actions with the same intention. High-density EEG neuroimaging combining brain microstate analysis with LAURA distributed linear source estimations expanded these results by revealing suppressed responses for intention decoding in this brain network in the early stage of processing (within the first 300 ms after the hand-on object interaction). Together, these results establish that intention understanding is mediated by a specific subset of regions within the human MNS that are different than those used to decode lower level visual features related to the object. The findings identify a time window of activity within MNS that may be critical for intention decoding. This could potentially be used for on-line monitoring of action awareness.