Characteristics of the Cortical and Hippocampal EEG Power Spectra of Rabbits during Normal Behavioral States and after Administration of CNS Acting Drugs

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Abstract
The EEG power spectra of the motor cortex (MC) and hippocampus (HPC) in rabbits were characterized, and the effects of CNS acting drugs on the spectra were investigated. The EEG of rabbits with chronically implanted electrodes were recorded with bipolar leads and the simultaneously analyzed for 15 min with a computer to obtain their power spectra. MC spectra had 1 peak of .delta. wave, and HPC spectra had 2 peaks of .delta. and .theta. waves, whose peak powers and frequencies were changed in correspondence to the level of consciousness. Pentobarbital (20 mg/kg, i.v.) produced the peaks at 11 and 4 Hz in MC and HPC spectra, respectively. Morphine (5 mg/kg, i.v.) produced the peak at 7 Hz in MC spectra and shifted the .theta. wave peak of HPC to lower frequencies. Diazepam (4 mg/kg, i.v.) produced the peak at 14 Hz in MC spectra and decreased the 2 peak powers in HPC spectra. Chlorpromazine (4 mg/kg, i.v.) shifted the .theta. wave peak of HPC to lower frequencies. Amitriptyline (5 mg/kg, i.v.) increased the peak powers of the .delta. waves in MC and HPC spectra. Each of the 5 CNS acting drugs produces the characteristic spectra, and they are different from the spectra obtained during normal behavioral states.