Morphine effects on the spontaneous electroencephalogram in polydrug abusers: correlations with subjective...

The spontaneous electroencephalogram (EEG) was recorded after the intramuscular (IM) injection of morphine sulfate (15, 30 mg) or saline (0.9% NaCl). Correlations between changes in EEG spectral power and subjective self-reports, as measured on subscales of the Addiction Research Center Inventory (ARCI), were evaluated. Morphine increased alpha 1 and alpha 2 power and theta power, and attenuated the increase in delta power observed after placebo. Positive correlations were found between the change in alpha 1, alpha 2, beta 1, and beta 2 power in response to 30 mg of morphine and scores on Morphine-Benzedrine Group (MBG) subscale of the ARCI. Negative relationships were observed between changes in alpha 1, and beta 2 and scores on the Pentobarbital Chlorpromazine Alcohol Group (PCAG) subscale. The findings indicate that positive subjective effects of opioids, as measured by the MBG subscale, are related to increases in alpha and beta activity and are associated with reduction of opioid-induced sedation, as measured by the PCAG subscale.