Effects of prenatal ethanol exposure on hippocampal theta activity in the rat

This study examined the effects of prenatal ethanol exposure on hippocampal theta activity in adult rats. Subjects were randomly selected from four prenatal treatment conditions: untreated, 0, 3, or 5 g/kg/day ethanol. At approximately 90 days of age, all subjects were surgically implanted with a bipolar electrode in the CA1 region of the hippocampus. Four epochs of hippocampal theta rhythm activity were recorded while the subjects were moving and four more while still, and a normalized theta score was computed and compared among groups. The 5 g/kg male group demonstrated a significantly higher theta score than controls, indicating either an increase in type I (movement-associated) theta and/or a decrease in type II (information-processing) theta activity. These results are consistent with prior reports that prenatal ethanol exposure alters hippocampal function and support clinical indications that monitoring the EEG of children may prove to be useful in the diagnosis of fetal alcohol syndrome and/or the detection of alcohol-related birth defects.