Humans in Love Are Singing Birds: Socially-Mediated Brain Activity in Language Production

Abstract This functional magnetic resonance imaging (fMRI) study investigated whether and how the human speech production circuit is mediated by social factors. Participants recited a poem in the MRI scanner while viewing pictures of their lover, unknown persons, or houses to simulate different social contexts. The results showed, as expected, the recruitment of the speech production circuit during recitation. However, for the first time, we demonstrated that this circuit is tightly linked to the network underlying social cognition. The socially relevant contexts (familiar and unfamiliar persons) elicited the recruitment of a widespread bilateral circuit including regions such as the amygdala, anterior cingulate, and orbitofrontal cortex, in contrast to the non-socially relevant context (houses). We also showed a neural gradient generated by the differences in the social relevance of affective and nonaffective contexts. This study opens up a novel line of research into socially mediated speech production, revealing drastic differences in brain activation when performing the same speech production task in different social contexts. Interestingly, the analogous avian anterior neural pathway in the zebra finch is also differentially activated when the bird sings facing a (potential) mate or alone. Thus, this study suggests that despite important phylogenetic differences, speech production in humans is based, as in songbirds, on a complex neural circuitry that is modulated by evolutionarily primordial aspects such as the social relevance of the addressee.