Newborn infants learn during sleep

Abstract

Newborn infants must rapidly adjust their physiology and behavior to the specific demands of the novel postnatal environment. This adaptation depends, at least in part, on the infant's ability to learn from experiences. We report here that infants exhibit learning even while asleep. Bioelectrical activity from face and scalp electrodes was recorded from neonates during an eye movement conditioning procedure in which a tone was followed by a puff of air to the eye. Sleeping newborns rapidly learned the predictive relationship between the tone and the puff. Additionally, in the latter part of training, these infants exhibited a frontally maximum positive EEG slow wave possibly reflecting memory updating. As newborns spend most of their time sleeping, the ability to learn about external stimuli in the postnatal environment during nonawake states may be crucial for rapid adaptation and infant survival. Furthermore, because eyelid conditioning reflects functional cerebellar circuitry, this method potentially offers a unique approach for early identification of infants at risk for a range of developmental disorders including autism and dyslexia.

Fig. 1.

(A) Sleeping newborn infant with the EEG net and air puff tube with an opening over the right eyelid. Speakers for tone presentation are located inside the pillows on either side of the infant's head. (B) The average probability of a conditioned eye movement response is shown for both the experimental and the control groups. In the experimental group, tones were immediately followed by a puff of air to the eye, whereas tones and air puffs were presented at random times in the control group.

Fig. 2.

Event-related scalp potential (ERP) evidence of successful conditioning in newborn infant conditioning: a positive slow wave to conditioned stimuli in the second half of the training session (shaded area). The ERP elicited in the first half of the experiment is depicted by the solid line, and the ERP elicited by stimuli in the second half is represented by the dashed line. The earlier auditory evoked potential (≈300 ms after tone onset) was present throughout training. The later positive slow wave activity (≈800 ms after tone onset) recorded from frontal electrodes (Inset in upper right), was present only in the latter half of the training session.