Mode of Action of Some Drugs Which Affect Learning and Memory

  • P. B. Bradley


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.


Variable Time Delay Facilitatory Effect Reversal Learning Excitatory Response Excitatory Action 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Boakes, R. J., P. B. Bradley, I. Briggs, and A. Dray: Antagonism of 5-hydroxytryptamine by LSD 25 in the central nervous system: a possible neuronal basis for the actions of LSD 25. Br. J. Pharmac. 40, 202–218 (1970).Google Scholar
  2. Bradley, P. B., and J. Elkes: The effects of amphetamine and D-lysergic acid diethylamide (LSD 25) on the electrical activity of the brain of the conscious cat. J. Physiol. 120, 13P (1953).Google Scholar
  3. Bradley, P. B., and J. Elkes: The effects of some drugs on the electrical activity of the brain. Brain 80, 77–117 (1957).CrossRefGoogle Scholar
  4. Bradley, P. B., and B. J. Key: The effect of drugs on arousal responses produced by electrical stimulation of the reticular formation of the brain. Electroenceph. clin. Neurophysiol. 10, 97–110 (1958).CrossRefGoogle Scholar
  5. Gaddum, J. H.: Antagonism between lysergic acid diethylamide and 5-hydroxytryptamine. J. Physiol. 121, 15P (1953).Google Scholar
  6. Key, B. J.: The effect of drugs on discrimination and sensory generalisation of auditory stimuli in cats. Psychopharmacologia 2, 352–363 (1961).CrossRefGoogle Scholar
  7. King, A. R., I. L. Martin, and K. A. Seymour: Reversal learning facilitated by a single injection of lysergic acid diethylamide (LSD 25) in the rat. Br. J. Pharmac. 45, 161–162 (1972).Google Scholar
  8. Martin, I. L., and G. B. Ansell: A sensitive gas chromatographic procedure for the estimation of noradrenaline, dopamine and 5-hydroxytryptamine in rat brain. Biochem. Pharmacol., in press (1972).Google Scholar
  9. Roberts, M. H. T., and P. B. Bradley: Studies on the effects of drugs on performance of a delayed discrimination. Physiol, and Behav. 2, 389–397 (1967).CrossRefGoogle Scholar

Copyright information

© Plenum Press, New York 1973

Authors and Affiliations

  • P. B. Bradley
    • 1
  1. 1.Department of Pharmacology (Preclinical)Medical SchoolBirminghamEngland

Personalised recommendations