Mode of Action of Some Drugs Which Affect Learning and Memory
The effects of a number of centrally active drugs on the performance of a delayed discrimination task involving “recent memory” have been tested in primates. Whilst most of the drugs used disrupted performance, LSD 25 had a facilitatory effect 72 and 96 hours after injection. This drug was also found to facilitate reversal learning in rats, and this effect was accompanied by a significant increase of 5-HT levels in the brain. The results of investigations into the actions of LSD 25 on single neurones in the brain stem, using the technique of microiontophoresis have shown that the drug selectively antagonises the excitatory actions of 5-HT and in some cases also glutamate excitation. It is suggested that this action may be the basis for the psychotomimetic properties of LSD 25 and might also account for its effects on learning and memory.
KeywordsVariable Time Delay Facilitatory Effect Reversal Learning Excitatory Response Excitatory Action
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