PNAS: MRI finds resting state networks in preterm human brain
Resting state networks (RSNs) largely emerge during the period of rapid neural growth in the third trimester of gestation, suggesting that formation takes place before the acquisition of cognitive competencies in later childhood, found a study published Nov. 1 in the Proceedings of the National Academy of Sciences (PNAS).
“Previous studies at the time of normal birth have detected RSNs in the primary visual areas, somatosensory and motor cortices, temporal cortex, cerebellum and prefrontal cortex but did not find the complete default mode network, executive control network, or dorsal visual network,” offered Valentina Doria, PhD, of the Institute of Clinical Sciences at Imperial College Healthcare NHS Trust in Londonand colleagues. “This led to the suggestion that the full architecture emerges during later childhood in parallel with the development of corresponding cognitive functions.”
Despite this theory, the researchers tested for the alternative hypothesis: that the full collection of resting state dynamics emerges during the period of rapid neural growth before the normal time of birth at term.
Doria and colleagues utilized a series of independent analytical techniques, including registration and a spatiotemporal atlas of the developing brain with consistent thresholding in order to detect spontaneous spatially coherent fluctuations of the blood oxygen level-dependent (BOLD) signal by functional MRI in 70 infants. Each infant involved in the study was born between 29 and 43 weeks of postmenstrual age, with some undergoing scans with sedation and others with no sedation.
The development of the RSNs at 30 weeks postmenstrual age were characterized, charted and compared to those of adults at full term. The authors found that visual, auditory, somatosensory, motor, default mode, frontoparietal and executive control networks developed at different rates. While some activation patterns were not found in the most preterm group, all major RSNs characterized in the adult brain could be detected at the time of a full term birth, several of which were integrated with thalamic activity, wrote the researchers.
According to Doria and colleagues, the RSNs mainly develop after 30 weeks gestation and are largely complete by 40 weeks. Additionally, no differences in results between sedated and non-sedated babies were noted.
“This study shows that RSNs develop with different trajectories but that the repertoire of resting state dynamics emerges during the period of rapid neural growth in the last trimester of gestation, before the acquisition of cognitive competencies,” the study concluded.
“Previous studies at the time of normal birth have detected RSNs in the primary visual areas, somatosensory and motor cortices, temporal cortex, cerebellum and prefrontal cortex but did not find the complete default mode network, executive control network, or dorsal visual network,” offered Valentina Doria, PhD, of the Institute of Clinical Sciences at Imperial College Healthcare NHS Trust in Londonand colleagues. “This led to the suggestion that the full architecture emerges during later childhood in parallel with the development of corresponding cognitive functions.”
Despite this theory, the researchers tested for the alternative hypothesis: that the full collection of resting state dynamics emerges during the period of rapid neural growth before the normal time of birth at term.
Doria and colleagues utilized a series of independent analytical techniques, including registration and a spatiotemporal atlas of the developing brain with consistent thresholding in order to detect spontaneous spatially coherent fluctuations of the blood oxygen level-dependent (BOLD) signal by functional MRI in 70 infants. Each infant involved in the study was born between 29 and 43 weeks of postmenstrual age, with some undergoing scans with sedation and others with no sedation.
The development of the RSNs at 30 weeks postmenstrual age were characterized, charted and compared to those of adults at full term. The authors found that visual, auditory, somatosensory, motor, default mode, frontoparietal and executive control networks developed at different rates. While some activation patterns were not found in the most preterm group, all major RSNs characterized in the adult brain could be detected at the time of a full term birth, several of which were integrated with thalamic activity, wrote the researchers.
According to Doria and colleagues, the RSNs mainly develop after 30 weeks gestation and are largely complete by 40 weeks. Additionally, no differences in results between sedated and non-sedated babies were noted.
“This study shows that RSNs develop with different trajectories but that the repertoire of resting state dynamics emerges during the period of rapid neural growth in the last trimester of gestation, before the acquisition of cognitive competencies,” the study concluded.