Physiological correlates of memory recall in infancy: vagal tone, cortisol, and imitation in preterm and full-term infants at 6 months

Abstract

We examined the role of physiological regulation (heart rate, vagal tone, and salivary cortisol) in short-term memory in preterm and full-term 6-month-old infants. Using a deferred imitation task to evaluate social learning and memory recall, an experimenter modeled three novel behaviors (removing, shaking, and replacing a glove) on a puppet. Infants were tested immediately after being shown the behaviors as well as following a 10-min delay. We found that greater suppression of vagal tone was related to better memory recall in full-term infants tested immediately after the demonstration as well as in preterm infants tested later after a 10-min delay. We also found that preterm infants showed greater coordination of physiology (i.e., tighter coupling of vagal tone, heart rate, and cortisol) at rest and during retrieval than full-term infants. These findings provide new evidence of the important links between changes in autonomic activity and memory recall in infancy. They also raise the intriguing possibility that social learning, imitation behavior, and the formation of new memories are modulated by autonomic activity that is coordinated differently in preterm and full-term infants.

Figure 1

Relation between delta vagal tone and imitation behavior during immediate testing in full-term infants. Note: Greater suppression of vagal tone predicted better imitation scores in full-term infants during immediate testing.

Figure 2

Relation between delta vagal tone and imitation behavior during delayed testing in preterm infants. Note: Greater suppression of vagal tone predicted better imitation scores in preterm infants during delayed testing.

Figure 4

The percent of infants who removed the mitten (Panel A), shook the mitten (Panel B), and/or replaced the mitten on the puppet (Panel C) during immediate and delayed testing as a function of group and vagal tone suppression.