Neural correlates of memory for faces

When we encounter someone in our dairy lives, we have some impressions of that person. Previous psychological studies have reported that the impressions for ather people affect memory for faces of other people. However, little is known about the neural mechanisms underlying the effects of face-based impressions on memory for faces. The goal of this review article is to review functional neuroimaging findings which investigate neural activations related to the effects of facial expressions, attractiveness, and trustworthiness on memory for faces, and to propose a functional model regarding the memory processing of faces. Three major findings emerged from this review. First, face-based positive signals, including the smiling expression and facial attractiveness, enhanced memory for faces, and the memory enhancement was involved in an interaction between activities in the reward-related orbitofrontal cortex and the memory-related hippocampus. Second, the information of untrustworthiness conveyed from faces enhanced the remembering of faces, and an interaction between activities in the punishment-related insula and the memory-related hippocampus contributed to this memory enhancement. Third, the processing of facial attractiveness highly correlated with the processing of trustworthiness, and the orbitofrontal and insular cortices, in which activities were negatively correlated, showed significant activations in each process of face-based positive and negative signals. Memory for faces could be organized by the "core" system, which is involved in the basic memory process of faces, and the "sub" system, which is important in the modulation of memory for faces.