Trends in Neurosciences
Volume 24, Issue 3, 1 March 2001, Pages 129-130
Journal home page for Trends in Neurosciences

Research update
Abnormal cognition and behavior in preterm neonates linked to smaller brain volumes

https://doi.org/10.1016/S0166-2236(00)01747-1Get rights and content

Abstract

Volumetric measurements of the brain regions in eight-year-old children indicate that the poor cognitive and behavioral outcomes noted in ex-preterm neonates are associated with reduced volumes of specific regions in the brain. Recent literature suggests that this reduction might result from enhanced apoptosis or excitotoxic damage to highly susceptible immature neurons.

Section snippets

Increased vulnerability of prenatal neurons

The neurological maturity of 6–10 day-old newborn rat pups corresponds to the crucial period for human brain development that occurs from the time just before birth to the time just after. This period is associated with peak rates of brain growth 6, synaptogenesis 7, and also with major changes in the expression, structure, and function of specific receptor populations, such as NMDA receptors that are a key component of excitotoxic cell death. Immature neurons have altered Ca 2+ signaling

Effect of adverse experiences

Animal models of hypoxia-ischemia, performed in neonatal rats have shown increased neuronal necrosis in the cerebral cortex, striatum, thalamus, and hippocampus 14. Similarly, infection of the neonatal mouse brain causes increased cortical and hippocampal apoptosis 15. In addition, models of sepsis and endotoxemia in neonatal pigs demonstrate increase susceptibility to neuronal and astrocytic injury in the frontal cortex associated with impaired integrity of the blood–brain barrier 16. Other

Concluding remarks

In spite of the improved survival of tiny preterm neonates, their neurodevelopmental outcomes remain a cause for grave concern. The two primary mechanisms leading to enhanced neuronal cell death in the immature brain are hypothesized to be: NMDA-mediated excitotoxicity (not discussed here); and enhanced naturally occurring neuronal apoptosis during early development as a result of multiple metabolic stresses.

The pattern and magnitude of abnormalities will depend on genetic variability as well

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