Effect of Electrical Stimulation and Lesion of Nucleus Accumbens on EEG of Intact and Addicted Rats

The nucleus accumbens is involved in various functions ranging from motivation and reward to feeding and drug addiction. Some researchers have also suggested that this region has some roles in consciousness. In the present study, the effect of electrical stimulation and lesion of nucleus accumbens on Electroencephalogram waves (EEG) of addict and non-addict rats was investigated. Male wistar rats (weight 190-250 g) were divided into control and addict groups. Addiction was induced by injection of morphine (three times a day and for four days). Then all rats in both groups were aneasthetized by urethane and stainless steel electrodes were implanted in nucleus accumbens. EEG waves were recorded in three stages of control, after stimulation (130µA, 100HZ, every 5sec for 10 min), and after lesion (0.4 mA, 60 sec) of nucleus accumbens in each group. In addict group alpha and betha waves were increased, while theta and dltha waves were decreased compared to intact group. Electrical stimulation and lesion of nucleus accumbens decreased theta waves in intact group and increased betha waves in addict group comparing to the control stages. Although morphine dependency causes increase of high frequency- low voltage waves and decrease of low frequency-high voltage waves, it seems, that nucleus accumbens has no role in variations of brain waves.