On acute effects of some drugs on the higher nervous activity in man. Ethanol (0.5 g/kg) and its interaction with diazepam (5 mg) and meclophenoxate (100 mg). Part LVIII.

1. Acute effects of ethanol (0.5 g/kg of body weight) and its interactions with diazepam (5 mg) and meclophenoxate (100 mg) and placebo on the higher nervous activity were tested on a group of 16 healthy and unfatigued volunteers-university students (8 females, 8 males, aged 21 years). The experimental subjects were given the following combinations of the studied drugs: (a) Ethanol plus meclophenoxate, (b) Ethanol plus placebo, (c) Ethanol plus diazepam, (d) Placebo solution plus placebo. The method of artificial conditioned speech connections was made use of. Three statistically balanced trials were always carried out: before, and one and two hours after the administration of the tested drug combinations during the early and late forenoon hours. The investigation-sets consisted of two optic, two complex tactile, and two acoustic associations. The criteria for the evaluation of the results were the number of repetitions necessary for mastering the given task, then the number of correct responses and the frequencies of responses in the first eight repetitions of the sets when the active knowledge of the persons under investigation was tested. 2. One hour after the application, there appeared a statistically significant impairment in NNR and NCR, both after ethanol alone and ethanol in combinations with diazepam and meclophenoxate. The frequency of responses was impaired only after the combination of ethanol plus diazepam. 3. Two hours after the administration, the combinations of ethanol plus diazepam and ethanol plus meclophenoxate impaired significantly the number of necessary repetitions. NCR impairment was observed only after application of ethanol with diazepam. Ethanol administered separately did not impair the followed up characteristics of learning. 4. The most marked effect appeared during the formation of artificial conditioned speech connections with acoustic stimuli.