An action-observation network in the common marmoset identified by ultra-high field fMRI

Abstract

Thirty years have passed since the first description of neurons in Old World macaque monkeys that fire both during the execution and observation of goal-directed actions. Since then, these so-called “mirror neurons” have been shown to play important roles in understanding the actions of others, learning by imitation, and social cognition in macaques and humans. In contrast to Old World primates, an action-observation network has not yet been identified in New World primates. Here we used ultra-high field fMRI at 9.4T in awake common marmosets (Callithrix jacchus) while they watched videos depicting the upper-limb of marmosets performing goal-directed (grasping food) or non-goal-directed actions. We found that the observation of goal-directed actions, compared to non-goal directed ones, activated a frontotemporoparietal network, including areas 6 and 45 in premotor and prefrontal cortices, and areas PGa-IPa, FST, and the TE complex in temporoparietal regions. These results demonstrate the existence of an evolutionarily conserved action observation network in primates that likely predates the separation of Old and New World monkeys.