Amnesic Actions of Diazepam and Scopolamine in Man

In man, diazepam alone and in combination with scopolamine interferes with the memory of visual and painful stimuli. With a 15-minute interval between injection of the drug and the showing of emotionally neutral pictures, scopolamine (0.5 mg/70 kg) produces 14 per cent forgetting when evaluated 24 hours later. Under these conditions diazepam (10 mg/70 kg) produces 41 per cent forgetting, while the combination causes 64 per cent. Under conditions designed to insure selection of subjects in whom registration was clearly quite intact at the time of the initial exposure to the pictures, memory was still found to be impaired when tested 24 hours later. Graded doses of diazepam to as much as mg/70 kg in combination with 0.5 mg/70 kg scopolamine produced a virtually linear dose-response curve for amnesia. These results are compatible with the interpretation that the diazepam-scopolamine mixture interferes with memory by blocking consolidation of the memory trace.