Working memory in preterm and full-term infants

Jing Sun, Nicholas Buys

Research output: Book chapter/Published conference paperChapter


Introduction This study investigated working memory in preterm and full-term infants at 8 months after expected date of delivery. Working memory is defined as "the ability to maintain an appropriate problem solving set for the attainment of a future goal" [1,p. 201]. An important characteristic of working memory is that it is prospective, that is, its purpose is to attain a goal, and it not only enables information to be held in mind but also to be manipulated. Working memory emerges in infancy and continues to develop throughout childhood. Working memory is believed to underlie some learning problems in children at school age. Although numerous studies have reported that the overall development of preterm infants is comparable to that of full-term infants at the same corrected age, it is unclear to what extent the development of specific cognitive abilities is affected by prematurity and/or other factors such as medical complications. As preterm infants have a high rate of learning difficulties, it is possible that factors associated with prematurity specifically affect the development of some regions of the brain associated with the regulation of working memory. Methods The current study aimed to examine the effects of maturation and length of exposure to extrauterine environmental stimuli on the development of working memory, by comparing the development of preterm infants with that of full-term infants at both thesame corrected age and the same chronological age. A case-control study design was used for the study. Thirty-seven preterm infants without identified disabilities and 74 fullterm and gender matched healthy full-term infants participated in the study. The preterm infants were all less than 32 weeks gestation and less than 1500 grams birthweight. All infants were assessed on working memory tasks at 8 months after the expected date of delivery (when preterm infants were actually 10-11 months chronological age). Results The findings of the study showed that preterm infants performed significantly more poorly than full-term infants at 8 months after the expected date of delivery on measures of working memory. The results suggest that the effects of maturation are greater than the effects of exposure to extrauterine environmental stimuli on the development of working memory. Furthermore, the preterm infants were divided into two subgroups on the basis of (a) low or high medical risk factors, (b) birthweight of < 1000g versus 1000-1500g, and (c) gestation age of < 28 weeks versus 28-32 weeks, in order to assess the effects of these variables on the performance of working memory. Medical risk, lower birthweight and lower gestation age were all found to adversely affect performance on working memory. Discussions and Conclusions It is argued that medical risk, lower birthweight and lower gestation factors may influence the development of specific areas of the brain which govern working memory, and given that the prefrontal regions are particularly immature they may be especially vulnerable to damage or disruption. The present study provides further insights into the emergence of working memory in infants and the feasibility of evaluating these abilities in infants who are at risk for further learning difficulties and attention deficits.

Original languageEnglish
Title of host publicationWorking Memory
Subtitle of host publicationCapacity, Developments and Improvement Techniques
PublisherNova Science Publishers
Number of pages25
ISBN (Print)9781617619809
Publication statusPublished - Feb 2011


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