Abstract
A fundamental issue in cognitive neuroscience is how the brain encodes others’ actions and intentions. The discovery of an action-production-perception mechanism underpinning such a capacity advanced our knowledge of how these processes occur; however, no study has examined how the early postnatal environment may shape action-production-perception. Here we examined the effects of social experience on action-production-perception in 3-day-old rhesus macaques that were raised either with or without their biological mothers. We measured neonatal imitation skills and brain electrical activity responses while infants produced and observed facial gestures. We hypothesized that early social experiences may shape brain activity, as assessed via electroencephalogram suppression in the alpha band (5-7 Hz in infants, known as the mu rhythm) during action observation, and lead to more proficient imitation skills. Consistent with this hypothesis, infants reared by their mothers were more likely to imitate lipsmacking—a natural, affiliative gesture—and exhibited greater mu rhythm desynchronization while viewing lipsmacking gestures than nursery-reared infants. These effects were not found in response to tongue protrusion, a meaningless gesture, or a nonsocial control. These data suggest that socially enriched early experiences in the first days after birth increase brain sensitivity to socially relevant actions.
