LAUSR

Electrographic seizures and abnormal background activity in the neonatal electroencephalogram (EEG) may differentiate between harmful versus benign brain insults. Using two animal models of neonatal seizures, electrical activity was recorded in freely behaving rats and examined quantitatively during successive time periods with field-potential recordings obtained shortly after the brain insult (i.e., 0-4 days). Single-channel, differential recordings with miniature wireless telemetry were used to analyze spontaneous electrographic seizures and background suppression of electrical activity after: [a] hypoxia-ischemia (HI), which is a model of neonatal encephalopathy that causes acute seizures and a large brain lesion with possible development of epilepsy, [b] hypoxia alone (Ha), which causes severe acute seizures without an obvious lesion or subsequent epilepsy, and [c] sham control rats. Background EEG exhibited increases in power as a function of age in control animals. Although background electrical activity was depressed in all frequency bands immediately after HI, suppression in the beta and gamma bands was greatest and lasted longest. Spontaneous electrographic seizures were recorded, but only in a few HI-treated animals. Ha-treated rat pups were similar to sham controls: they had no subsequent spontaneous electrographic seizures after the treatment, and background suppression was only briefly observed in one frequency band. Thus, the normal age-dependent maturation of electrical activity patterns in control animals was significantly disrupted after HI. Suppression of the background EEG observed here after HI-induced acute seizures and subsequent brain injury may be a non-invasive biomarker for detecting severe brain injuries, and may help predict subsequent epilepsy.