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Melatonin: effect on punished and nonpunished operant behavior of the pigeon

R I Schoenfeld

    Science (New York, N.Y.)
    |March 26, 1971
    PubMed

    Insights

    Intramuscular melatonin injections increased response rates in a dose-dependent manner under a fixed-interval schedule. Adding a punishment contingency did not increase overall rates but did increase early-interval responding.

    Area of Science:

    • Behavioral pharmacology
    • Neuroscience
    • Animal behavior

    Background:

    • Melatonin is a hormone regulating sleep-wake cycles.
    • Its effects on operant behavior are not fully understood.
    • Previous research suggests potential roles in modulating arousal and attention.

    Purpose of the Study:

    • To investigate the effects of intramuscular melatonin injections on operant responding.
    • To examine how melatonin influences behavior under different reinforcement and punishment schedules.

    Main Methods:

    • Rats were trained to respond on a fixed-interval (FI) schedule of positive reinforcement.
    • Melatonin was administered via intramuscular injection in a dose-dependent manner.
    • A punishment contingency was introduced to the FI schedule to assess its interaction with melatonin's effects.

    Main Results:

    • Melatonin produced a dose-dependent, rate-increasing effect on responding maintained by the FI schedule.
    • When punishment was added, overall response rates did not increase.
    • However, responding during the initial portion of each FI interval was enhanced by melatonin under the punishment condition.

    Conclusions:

    • Melatonin can modulate operant behavior, increasing response rates under certain conditions.
    • The effects of melatonin may differ depending on the presence of punishment contingencies.
    • Further research is needed to elucidate the neurobiological mechanisms underlying melatonin's behavioral effects.

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