DISSOCIATION OF MOUTH AND HEAD MOVEMENTS DURING MARMOSET MONKEY FETAL DEVELOPMENT

Abstract

All primates engage in vocal communication. Precise control of the mouth musculature is very important for the production of species-typical vocalizations. Isolated movements are known to emerge from a pattern of more general movement. Our study looked at the differentiation of mouth movements from a more general movement pattern involving combined mouth and head movements. We studied common marmoset (Callithrix jacchus) monkeys and performed ultasonography exams to track the degree of overlap between mouth and head movements through gestation and found that the percentage of overlapping movements decreased over time. Our findings suggest that mouth movements and head movements are linked in early gestation but gradually differentiate to become two independent movement patterns by the end of gestation.