Babies born prematurely show the same kind of brain activation seen in adults: but it's a lot slower. That's according to
using fMRI scanning.
The authors, Tomoki Arichi and colleagues of London, measured brain activation in response to mild sensory stimulation (touching the right hand) in three groups: adults, "preterm" infants who were just 38 weeks old since conception, and "term" infants who'd been conceived about 42 weeks before scanning, although many of these had also been born prematurely.
Activation was observed in the same part of the brain in all three groups, showing that the BOLD blood oxygenation response measured by fMRI is present even early in life. However, in the pre-term infants, it was delayed: while in adults and typical infants it peaked about 6 seconds after stimulation, in the preterms it was more like 12 seconds. The size of the response was much smaller than in adults in both cases, though.
The authors say that the brain itself is probably not the source of the difference. Rather, they argue that in preterm infants, the blood supply to the brain takes longer to respond to the need for more oxygen.
Arichi T, Fagiolo G, Varela M, Melendez-Calderon A, Allievi A, Merchant N, Tusor N, Counsell SJ, Burdet E, Beckmann CF, and Edwards AD (2012). Development of BOLD signal Hemodynamic Responses in the Human Brain. NeuroImage PMID: 22776460