The association between active sleep and development of the superior and middle cerebellar peduncles in extremely and very preterm infants
Summary
Background: Extremely and very preterm infants (<28 and <32, respectively) are born within a vulnerable period of brain development, often causing atypical brain development at term-equivalent age and beyond. Around 30 weeks of gestation, the brain’s white matter is especially vulnerable. At the same time, the neurodevelopmental process of pre-myelination is at full speed and it is also the period in which the predominant brain activity is active sleep. Active sleep is thought to be an important driver of white matter development, a sleep stage dominated by large amounts of non-reflexive body movements, called twitches. Rodent studies have shown neural circuits are activated during twitches, providing a sensory feedback loop in which the cerebellum plays an important role. This led to the hypothesis that active sleep contributes to development of the cerebellar tracts. This study aimed to test if more active sleep at 30 weeks post-menstrual age, would lead to more advanced maturation of the superior and middle cerebellar peduncle.
Method: In total 56 preterm infants with a gestational age at birth of 24+4 to 29+4 participated in this study. Sleep was measured around 30 weeks post-menstrual age (5-7 consecutive days) based on heartrate and respiratory rate, and an average percentage of sleep stages per 24 hours was calculated. Fractional anisotropy and mean diffusivity were used to indicate maturation of the tracts at 40 weeks post-menstrual age, calculated using region-of-interest analysis on diffusion-tensor-imaging data.
Results: Active sleep covered 44.87 percent of the total sleep time. Active sleep did not significantly predict fractional anisotropy, nor mean diffusivity for the superior and middle cerebellar peduncles. The covariate days on ventilation was found to be significant predictor for fractional anisotropy values of the middle cerebellar peduncle (β = -0.04, p = .014, R2 = 0.02).
Conclusion: The present study could not predict maturation of the cerebellar tracts by active sleep around 30 weeks post-menstrual age. As this was the first human study on this specific topic, this study should be replicated preferably also including automated region-of-interest analysis.