Fig 3.

Frontal and occipital power distribution at slow, delta, and alpha frequencies during sevoflurane-maintained surgical anaesthesia in children from 0 to 3 yr. Peak frontal and occipital EEG power in the (a) slow (0.1–1 Hz), (b) delta (1–4 Hz), and (c) alpha (8–12 Hz) frequency bands for each subject are plotted as a function of age. The solid line represents fourth-degree polynomial-regression model describing the relationship between age and EEG power (blue line, frontal power; red line, occipital power; dashed lines, 95th percentile confidence boundaries); the inset schematic indicates the location of the frontal and occipital channels. Differences in power between frontal and occipital channels in the (d) slow, (e) delta, and (f) alpha frequency bands are presented with 95% CI from bootstrap analysis (pink line, 97.5th percentile; green line, 2.5th percentile). Slow and delta oscillations exhibit a small and significant increase in frontal power compared with occipital power from mid-to late infancy until ∼26–30 months of age. Alpha oscillations emerge around 3–4 months of age and exhibit a significant and sustained frontal predominance of power that begins to emerge at 8 months of age and peaks at ∼15–20 months of age. These data indicate that adultlike patterns of activity are detectable from infancy. F3 and O1 electrodes are presented using nearest-neighbour Laplacian referencing. CI, confidence interval.