Tolonen M, Palva J M, Andersson S, Vanhatalo S
Department of Pediatrics, Hospital for Children and Adolescents, University Hospital of Helsinki, Helsinki, Finland.
Neuroscience. 2007 Mar 30;145(3):997-1006. doi: 10.1016/j.neuroscience.2006.12.070. Epub 2007 Feb 20.
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.
最近的实验研究表明，包括人类在内的几种动物物种的发育中的皮质表现出自发性间歇性活动，这种活动被认为对早期脑网络的正确布线至关重要。本研究调查了人类早产儿这些自发活动瞬变（SAT）以及其他持续皮质活动的发育变化。从16名孕龄在32.8至40周的婴儿身上获取了全频段脑电图（FbEEG）记录。我们通过平均波形、其方差和功率以及基于小波的时频分析来研究SAT和其间的持续皮质活动（SAT间期；iSAT）。我们的结果显示，SAT的低频功率和平均波形的方差在发育过程中降低。高频活动同时增加，在θ-α范围（4-9赫兹）增加最为明显。除了整体增加外，高频活动表现出更多地分组为嵌套在低频（0.5-1赫兹）波中的爆发。对iSAT时段的分析显示，安静睡眠中低频功率在发育过程中增加。广泛的高频（4-16赫兹）有增加，而β（16-30赫兹）和θ-α（4-9赫兹）范围活动的比率下降，表明θ-α范围活动有优先增加。值得注意的是，在我们研究中使用的所有测量方法中，SAT和iSAT活动在整个发育过程中都保持不同。目前的结果与SAT和其他持续皮质活动是不同功能实体的观点一致。认识到人类早产儿皮质活动中的这两种基本机制为评估和监测早期人类脑功能开辟了新的合理方法。
