Prefrontal cortex-mediated inhibition supports face recognition.

Inhibitory processes are thought to be important for memory function. A recent behavioral study that employed a face recognition paradigm reported that participants made fewer "old" responses to highly similar faces than less similar faces, providing evidence that memory for faces may rely on related-item inhibition. However, these results could also be explained by a non-inhibitory recall-to-reject process. The current study sought to use fMRI connectivity analysis to distinguish between these hypotheses. Although both hypotheses predict correct rejection of highly similar faces will produce activity in the prefrontal cortex, the inhibition hypothesis predicts negative connectivity between the prefrontal cortex and regions associated with memory retrieval and face processing, whereas the recall-to-reject hypothesis predicts positive connectivity between these regions. During the study phase, participants were presented with male and female faces. During the test phase, they viewed old faces, related face morphs (20-80% similar to old faces), and new faces, and made "old"-"new" judgements. Correct rejection of highly similar face morphs was associated with increased activity in the right lateral prefrontal cortex and negative connectivity between this region and regions associated with face processing and memory retrieval. These results indicate that prefrontal cortex-mediated memory inhibition supports face recognition.