Sleep and circadian rhythms and their importance in memory formation and cognition are topics of high interest to neuroscience researchers, both from a biochemical and behavioral perspective. Much of this research has had a focus on the brains of children and adults; a developmental perspective in sleep research is harder to find. Previous research has identified sleep as a key factor in long-term memory consolidation and heightened cognitive abilities, but this naturally poses the question: How do the emergence of circadian rhythms and attention to healthy sleep patterns in infantry affect the infant's cognitive development? Dr. Dan Cavanaugh, Dr. Elaine Tham, and their colleagues have used this question and the smaller amount of information on it to fuel their research on sleep in the brains of infants.
Dr. Cavanaugh, who spoke during our seminar, used Drosophila to examine the ability to form short- and long-term memories before and after the larvae seemingly developed circadian rhythms. They utilized the method of aversive associative olfactory learning to test if flies at a variety of larval stages associated a certain odor with a bitter taste and "found that L2 [pre-circadian rhythm development] did not show LTM, but early L3 [post-circadian rhythm development] exhibited a strong persistent memory of the aversive cue" (Cavanaugh et al.) Furthermore, they also found that L3 larvae did not perform well if they were sleep-deprived after learning, indicating that even after the development of a circadian rhythm and the ability to form long-term memories, sleep is crucial. Rhythmic sleep cycles emerge to enable deeper sleep, "unlocking more sophisticated brain function" (Cavanaugh et al.) This information on the development of sleep rhythms and the ability for heightened cognitive function, including that of memory formation, indicates a strong correlation and possible causation between the two.
The research of Dr. Tham and her colleagues takes an investigative approach to previous studies on infant sleep and its correlation to cognitive development. They identified sleep as "a highly dynamic developmental process, particularly in the first 2 years of life, with a high inter- and intraindividual variability" (Tham et al.) Tham and her team read through thousands of research articles about the topic of interest and extracted about 30 relevant articles from various sources. Many of the studies discussed in the articles focused on how napping after learning affected retention and identification of the learned material, which included object-action pairings and artificial language, leading to a general finding of the overall benefit of sleep in retention. Examination of all relevant research articles led to the conclusion that greater sleep efficiency and longer proportions of sleep at night have a positive correlation with cognitive development, problem-solving skills, and "subsequent executive functioning during toddlerhood and early childhood" (Tham et al.)
Many similarities can be identified between these two studies as they are developing on the shared topic of rhythmic sleep cycles and their development in infantry. Furthering research on how circadian rhythms develop early in life is crucial in the subsequent study of how these sleep rhythms affect cognition, specifically long-term memory formation in the case of Dr. Cavanaugh's research. Understanding cognitive behavior related to sleep in infants can be troublesome with a lack of development of the biological and molecular perspective on circadian rhythms, and in this way, these two studies are supplemental. Enhancement of cognitive abilities and maturation of sleep patterns are both critical to natural and healthy infant development and research into how these attributes manifest neurologically and behaviorally are both of equal importance in gaining a heightened understanding of human development.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5440010/
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