Background and aim Early brain activity is crucial for neuronal growth. It is well known that the cerebral cortex develops rapidly in the last trimester of pregnancy. We investigated whether early brain activity was related to the rate of cortical development over the 10 wks before term equivalent age in preterm infants.

Methods 35 infants (GA: 27.1 ± 0.7; BW: 937 ± 172) without morphine, were monitored with EEG/aEEG. Three periods were selected at 20–24 h, 32–36 h, 44–48 h. Minimum amplitude,% of time

Results Increased SATrate was positively associated with deltaGMv, inner and outer surface (resp β:7.4, p:0.001; β:46.6,p:0.002; β:57.5, p:0.001). Consistent with these findings, ISI was negatively associated with changes in GMv, inner and outer surface (β:-3.4, p: 0.007; β:-17.8, p: 0.034; β:-27.7, p: 0.006). Min aEEG and% of time <5 µV were associated with inner and outer surface at 40 wks (respectively: β:46.2, p:0.043; β:53.0, p:0.041; and β:-2.9, p:0.025; β:-3.5, p:0.019). No effect on thickness and gyrification was found.

Conclusions Early brain activity seems to be associated with cortical development suggesting that adequate brain activity in the early neuronal networks is necessary to lead to growth and development of neonatal cerebral cortical brain, measured by structural MRI.