Glucocorticoids and Preterm Hypoxic-Ischemic Brain Injury: The Good and the Bad
Figure 3
Example of sleep state architecture in a 0.7 gestation preterm fetal lamb before exposure to maternal dexamethasone (panel (a)) and after dexamethasone (panel (b)). The normal sleep patterns of fetal sheep at this age is composed of mixed EEG amplitudes and frequencies, with mean amplitude typically around 60–70 μV. Transient waveforms (fast, sharp, and slow waves between 70–400 ms) are seen as part of this normal EEG patterns and their amplitude is typically between 70–150 μV. After dexamethasone exposure, there is a significant change in sleep architecture characterised by a significant increase in EEG amplitude (with background amplitudes increased to above 100 μV and spikes ranging between 200–600 μV), and a general reduction in high-frequency activity. Seizures and seizure-like activity is also observed and an example of this is shown in panel (c). While many of these seizures were high amplitude, it is notable that many were relatively low amplitude. All figures are raw data from one animal.
