Development of self-monitoring essential for vocal interactions in marmoset monkeys

In humans, self-monitoring is essential for conversations [1] and this ability is fully developed only after 2 years of age [2]. How vocal self-monitoring changes over the course of development, how it evolved, and how it is mediated by neural mechanisms are not known. In this study, we use marmoset monkeys to address these issues. We recorded natural vocal exchanges between parent and infant monkeys and looked for evidence of self-monitoring in both the adults and the infants. Our results show that, similar to humans, adult marmosets have the capacity to self-monitor whereas infants do not. Using a computational model of marmoset vocal exchange dynamics [3] we investigated possible neural mechanism underlying the development of self-monitoring. Our model is based on the interactions between three neural structures (representing limbic, motor and auditory regions) with feedback connectivity inspired by published physiological and anatomical data. The simulations show that strengthening the inhibitory connection between auditory and limbic regions drives the development of self-monitoring and, ultimately, adult-like vocal behavior.