Summary
Scopolamine was tested for effects on acquisition of a passive-avoidance problem. First mice were given four trials 24 hours apart on a step-off apparatus. Various dose levels of the drug were studied. For one group the drug was injected i.p. 20 minutes prior to each trial, in the other immediately after. Doses of 5.0 mg/kg and higher greatly interfered with the acquisition of the response, but only when injected prior to the trial. These results failed to indicate any direct effect of the drug on the learning process. The only time the drug affected the behavior was when the animal was under its influence at the time of testing.
A second experiment was conducted in which mice were trained as before but pre-injection of 5.0 mg/kg of scopolamine was used. However, the mice were injected with the drug on only some of the trials. In all, six groups were studied, and their performance compared with a group that had received scopolamine on all trials and with one that received saline on all trials. When the data were examined for evidence of dissociation, it was clear that it was not present. Further analysis showed that animals which had learned, as indicated by their performance on the early trials conducted when they were not drugged, failed to show evidence of memory when given additional trials after being drugged. This outcome clearly indicated that a major effect of scopolamine was on the performance of the animal. Also, animals which had received 1 or 2 trials while drugged and given additional trials in the nondrugged state, showed a rapid increase in latency on succeeding trials equal that of animals which had not been drugged at all.
These results, in light of other research, indicate that the effect of scopolamine on this type of learning task does not appear to be through a modification of the consolidation process.
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References
Bohdanecký, Z., and M. E. Jarvik: Impairment of one-trial passive avoidance learning in mice by scopolamine, scopolamine methylbromide, and physostigmine. Int. J. Neuropharmacol. 6, 217–222 (1967).
Burešová, O., J. Bureš, Z. Bohdanecký, and T. Weiss: Effect of atropine on learning, extinction, retention, and retrieval in rats. Psychopharmacologia (Berl.) 5, 255–263 (1964).
Carlton, P. L.: Scopolamine, amphetamine and light-reinforced responding. Psychon. Sci. 5, 347–348 (1966).
—: Cholinergic mechanisms in the control of behavior by the brain. Psychol. Rev. 70, 19–39 (1963).
Essman, W. B., and H. Alpern: Single trial conditioning, methodology and results with mice. Psychol. Rep. 14, 731–740 (1964).
Longo, V. G.: Behavioral and electroencephalographic effects of atropine and related compounds. Pharmacol. Rev. 18, 965–996 (1966).
McGaugh, J. L., and L. Petrinovich: Effects of drugs on learning and memory. Int. Rev. Neurobiol. 8, 139–196 (1965).
Meyers, B.: Some effects of scopolamine on a passive avoidance response in rats. Psychopharmacologia (Berl.) 8, 11–119 (1965).
Oliverio, A.: Contrasting effects of scopolamine on mice trained simultaneously with two different schedules of avoidance conditioning. Psychopharmacologia (Berl.) 11, 39–51 (1967).
—: Effects of scopolamine on avoidance conditioning and habituation of mice. Psychopharmacologia (Berl.) 12, 214–226 (1968).
Overton, D. A.: State-dependent learning produced by depressant and atropinelike drugs. Psychopharmacologia (Berl.) 10, 6–31 (1966).
Tapp, J. T.: Cholinergic mechanisms in operant responding. J. comp. physiol. Psychol. 59, 469–472 (1965).
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A preliminary report of Experiment I was made at the Southeastern Psychological Association Annual Meeting in Atlanta, Georgia, April, 1967. Supported by NIMH Grant No. MH 12770-01 to the senior author.
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Calhoun, W.H., Smith, A.A. Effects of scopolamine on acquisition of passive avoidance. Psychopharmacologia 13, 201–209 (1968). https://doi.org/10.1007/BF00401400
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DOI: https://doi.org/10.1007/BF00401400