Neural representations of others in the medial prefrontal cortex do not depend on our knowledge about them

Earlier neuroimaging studies on social inferences applying repetition suppression indicated that psychological entities of persons are represented in the ventral medial prefrontal cortex (mPFC). These representations were identified by suppression of activation in neural populations after repetition of the same persons, and are interpreted as abstract summary representations for the repeated social entity. However, an alternative explanation might be that suppression for persons does not reflect the representation of a person as such, but rather some degree of knowledge about this person. The current study contrasted these hypotheses by manipulating repetition not only of a person, but also of the knowledge about that person. If a high level of knowledge plays a role in person representation, suppression effects in the mPFC would be larger for well-known persons as opposed to less-known persons (e.g., close friends versus acquaintances). Contrary to this alternative hypothesis, but in line with the original interpretation, our results revealed only suppression for person repetition in the ventral mPFC irrespective of knowledge level, suggesting that both well-known and lesser-known persons are represented in this area. Suppression areas for well-known and lesser-known persons were, however, only partly overlapping and the area for less-known others extended towards the dorsal mPFC.