Effects of atropine on the repeated acquisition and performance of response sequences in humans.
Anticholinergic drugs like atropine hurt learning new sequences more than doing old ones, peaking three to five hours after the dose.
01Research in Context
What this study did
Scientists gave healthy adults a memory drug called atropine. Then they asked them to learn new button-press patterns every session. They also asked them to repeat patterns they already knew.
The team watched how fast and how correctly the adults pressed the buttons for nine hours. They did this to see if the drug hurt learning more than it hurt doing old skills.
What they found
Atropine made people mess up new patterns more than old ones. It also slowed their pressing.
The worst problems showed up three to five hours after the pill. By nine hours the effects were gone.
How this fits with other research
WALLER et al. (1962) saw the same dose-by-dose method in dogs with chlorpromazine. Both studies map how one drug changes a steady operant baseline.
Burgess et al. (1986) found morphine helps punished responding only after monkeys first practiced mixed schedules. Like Fovel et al. (1989), the past learning history decides how strong the drug effect is.
McKearney (1976) showed amphetamine can either help or hurt punished behavior depending on the reinforcer. Fovel et al. (1989) match this idea: atropine hurts new learning more than old performance, showing the task itself guides the drug outcome.
Why it matters
If a client takes anticholinergic meds for asthma, Parkinson’s, or mood, expect new skills to suffer first. Old skills may look fine. Schedule teaching trials when blood levels are lowest, usually first thing in the morning or right before the next dose. Track errors session-by-session so you can tell the doctor if learning dips then bounces back.
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02At a glance
03Original abstract
The present study assessed a 24-hr time course for the acute effects of intramuscular injections of atropine sulfate (0, 1.5, 3.0, and 6.0 mg/70 kg) in healthy adult humans responding under a two-component multiple schedule of repeated acquisition and performance of response sequences. Subjects resided in an inpatient research ward for the duration of the study. In each component of the multiple schedule, subjects completed a different sequence of 10 responses in a predetermined order using three keys of a numeric keypad. In the acquisition component, the subjects' task was to acquire a new sequence each session. Eight sessions were conducted daily: one immediately before administration of the drug and then 0.5, 1.5, 3.0, 5.0, 7.0, 9.0, and 24.0 hr after administration. In the performance component, the response sequence always remained the same. Overall percentage of errors increased and overall response rates decreased in the acquisition and performance components as an orderly function of drug dose. However, these effects were selective in that behavior in the acquisition component generally was affected at lower doses than in the performance component. When behavior was affected in both the acquisition and performance components, the time courses of effects were similar. Drug effects began at 0.5 or 1.5 hr, reached peak effects between 3.0 and 5.0 hr, and returned to placebo levels between 7.0 and 9.0 hr postdrug in both schedule components. None of the drug doses produced reliable effects the day after drug administration (24-hr postdrug) in either schedule component. The present study provides the first within-subject assessment of the magnitude and duration of the effects of an anticholinergic on repeated acquisition and performance baselines and extends to atropine the selective effects on these two baselines demonstrated previously with other compounds in humans and nonhumans.
Journal of the experimental analysis of behavior, 1989 · doi:10.1901/jeab.1989.51-5