Electroencephalographic Power Spectral Profile in a Rat Model of Schizophrenia

We investigated electroencephalographic (EEG) changes associated with a non-competitive NMDA antagonist, MK-801, which induces schizophrenia-like symptoms in humans and stereotyped behaviors in rats. We paralyzed rats using a muscle relaxant to remove behavioral conditions on EEG activity. At least three days prior to the experiment, we installed screw electrodes over the frontal and parietal cortices and a tungsten wire into the hippocampus of each rat under anesthesia. MK-801 treatment produced characteristic behaviors such as head weaving, circling, and ataxia. We used EEG signals during still (Still), pancuroniumtreated(Paralysis), or MK-801-treated (MK-801) conditions to calculate the power spectra. Compared with the Still condition, the Paralysis condition produced a significant power increase at 5.5 Hz and significant power decreases at 3 Hz and over 7 Hz. Compared to the Paralysis condition, the MK-801 condition produced significant increases at 2.5-3 Hz, 8.5-10 Hz, and over 25 Hz. Therefore, the EEG power spectral profile developed during this study may represent the MK-801-induced functional state, which excludes its interaction with drug-induced movements.