Development of spontaneous activity transients and ongoing cortical activity in human preterm babies

University of Helsinki, Helsinki, Uusimaa, Finland
Neuroscience (Impact Factor: 3.36). 04/2007; 145(3):997-1006. DOI: 10.1016/j.neuroscience.2006.12.070
Source: PubMed


Recent experimental studies have shown that developing cortex in several animals species, including humans, exhibits spontaneous intermittent activity that is believed to be crucial for the proper wiring of early brain networks. The present study examined the developmental changes in these spontaneous activity transients (SAT) and in other ongoing cortical activities in human preterm babies. Full-band electroencephalography (FbEEG) recordings were obtained from 16 babies at conceptional ages between 32.8 and 40 wk. We examined the SATs and the intervening ongoing cortical activities (inter-SAT; iSAT) with average waveforms, their variance and power, as well as with wavelet-based time-frequency analyses. Our results show, that the low frequency power and the variance of the average waveform of SAT decrease during development. There was a simultaneous increase in the activity at higher frequencies, with most pronounced increase at theta-alpha range (4-9 Hz). In addition to the overall increase, the activity at higher frequencies showed an increased grouping into bursts that are nested in the low frequency (0.5-1 Hz) waves. Analysis of the iSAT epochs showed a developmental increase in power at lower frequencies in quiet sleep. There was an increase in a wide range of higher frequencies (4-16 Hz), whereas the ratio of beta (16-30 Hz) and theta-alpha (4-9 Hz) range activity declined, indicating a preferential increase at theta-alpha range activity. Notably, SAT and iSAT activities remained distinct throughout the development in all measures used in our study. The present results are consistent with the idea that SAT and the other ongoing cortical activities are distinct functional entities. Recognition of these two basic mechanisms in the cortical activity in preterm human babies opens new rational approaches for an evaluation and monitoring of early human brain function.

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Available from: Sampsa Vanhatalo
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    • "Electroencephalography (EEG) recordings of preterm foetuses and electrophysiological analyses of acute slices of foetal human cortex have found that oscillatory bursting activity develops in the cerebral cortex from 20 gestational weeks on, continuing up to birth, after which it eventually diminishes (Dreyfus-Brisac and Larroche, 1971; Khazipov and Luhmann, 2006; Lamblin et al., 1999; Moore et al., 2011; Tolonen et al., 2007). Synchronised bursting also develops in human mixed neuronal cultures derived from embryoid bodies (Heikkilä et al., 2009). "
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