Abstract
Faces are a primary source of social information, but little is known about the sequence of neural processing of personally relevant faces, such as those of our loved ones. We applied representational similarity analyses to EEG-fMRI measurement of neural responses to faces of personal relevance to participants – their romantic partner and a friend – compared to a stranger. Faces expressed fear, happiness or no emotion. Shared EEG-fMRI representations started 100ms after stimulus onset not only in visual cortex, but also regions involved in social cognition, value representation and autobiographical memory, including ventromedial prefrontal cortex, temporoparietal junction and posterior cingulate. According to established models of face recognition, these activations precede the stage of structural face encoding at around 170 ms after stimulus onset. Representations in fusiform gyrus, amygdala, insular cortex and N. accumbens were evident after 200 ms. Representations related to romantic love emerged after 400ms in subcortical brain regions associated with reward. Our results point to the prioritized processing of personal relevance with extensive cortical representation as soon as 100 ms after stimulus onset; preceding the stage of structural face encoding.
Significance Statement Models of face processing, supported by studies using EEG or fMRI, postulate that recognition of face identity takes place with structural encoding in the fusiform gyrus around 170 ms after stimulus onset. We provide evidence, based on simultaneous measurement of EEG and fMRI, that the high personal relevance of our friends’ and loved ones’ faces is detected prior to structural encoding. These effects start as early as 100 ms after stimulus onset and are not confined to visual cortex, encompassing brain regions involved in value representation, self-relevant processing and social cognition. Our findings imply that our brain can ‘bypass’ full structural encoding of face identity in order to prioritise the processing of faces most relevant to us.
