Neonatal Medicine: New insights into foetal brain development
CSC researchers have shown that babies born at full term already have fully developed resting state networks – constantly active systems of neurons that underlie many adult cognitive functions. Previously they were thought to develop alongside those functions during early childhood.
As the Roman philosopher Seneca remarked, ‘rest is far from restful’. The remark, it seems, was as prescient as insightful: MRI studies of blood oxygen levels in the brain reveal a constant, spontaneous flux of low-frequency oscillations that continue to operate when the subject is not focusing on a particular task. While the function of the oscillations remains a matter of debate, a number of studies have shown that the spontaneous networks of oscillations – called ‘Resting State Networks’ (RSNs) – mirror adult networks associated with carrying out specific tasks, which has led some researchers to suggest that they form during the emergence of cognitive competencies during early childhood.
However, a team led by David Edwards, Head of the Neonatal Medicine Group at the CSC, tested an alternative hypothesis: that the resting state networks are present, fully formed, by the time of birth. They used two complementary methods of defining resting state networks and a series of independent analytical techniques to determine the resting activity in a sample of 70 infants born at between 29 and 43 weeks of development, whose parents had consented for them to be involved in the study. They found the RSNs were largely laid down in the last 10 weeks before the normal time of birth during a spurt of neuronal development, and much earlier than previously thought. This shows that the infant brain is more highly developed than thought previously, with the infrastructure for adult brain function in place by the time of birth.
One particular resting state network identified – the default mode network – has been suggested to be involved in daydreaming and a sense of self. Says David Edwards: “Some researchers have said that the default mode network is involved in introspection – retrieving autobiographical memories and envisioning the future, etc. The fact that we found it in newborn babies suggests that either being a foetus is a lot more fun than any of us can remember – lying there happily introspecting and thinking about the future – or that this theory is mistaken.”
The nest step for this research is to see how the networks are affected by illnesses and to see if they can be used to diagnose problems.
David Edwards has recently been announced as the second recipient of the Imperial College London Doctor of Science degree (DSc), and the first within the Faculty of Medicine. The criteria states: “The Doctor of Science degree is awarded for published work of an exceptional standard, containing original contributions to the advancement of knowledge and learning which has given the candidate international distinction in their field. Candidates must be able to demonstrate a sustained contribution to their subject, as evidenced by seminal publications.” We would like to congratulate David on his achievement.
This work appears in PNAS.
Doria, V., Beckmann, C. F., Arichi, T., Merchant, N., Groppo, M., Turkheimer, F. E., Counsell, S. J., Murgasova, M., Aljabar, P., Nunes, R. G., Larkman, D. J., Rees, G., Edwards, A. D. (2010). Emergence of resting state networks in the preterm human brain. PNAS, in press.