Relationship between amphetamine-induced effects on EEG power spectra and motor activity in rats.

Amphetamine injection (2.5 mg/kg, SC) produced a significant quadratic trend in mean peak EEG frequencies in the theta band in one group of rats. Progressive increases in peak EEG frequencies occurred for approximately 30 min after amphetamine injection and were followed by progressive decreases through 100 min. These changes in peak EEG frequencies may have reflected pharmacokinetic properties of amphetamine. A significant and similar quadratic trend was seen in mean motor activity counts after amphetamine injection in a second group of rats. In addition, a significant positive correlation was found between amphetamine-induced effects on peak EEG frequencies and mean motor activity counts.