Monkeys use a distinct set of neurons to predict whether a fellow primate is likely to cooperate for a common good.

Keren Haroush and Ziv Williams at Harvard Medical School in Boston, Massachusetts, inserted electrodes into the brains of four rhesus macaques (Macaca mulatta) to record activity in hundreds of individual neurons in a specific area of the frontal lobe.

They then trained different pairs of macaques to play a computer game displayed on a shared screen. Both animals were rewarded with juice if they cooperated by selecting orange shapes instead of blue ones. A large subset of the animals' neurons fired in a pattern that accurately predicted their partners' intended, as-yet unknown, selections. This subset was distinct from other subsets that fired in patterns reflecting their own personal selections or the expected reward.

Changes in these newly identified 'other-predictive' neurons may be relevant in social behavioural disorders such as autism, the authors say.

Cell http://doi.org/2gn (2015)