The role of dopamine in reinforcement: changes in reinforcement sensitivity induced by D1-type, D2-type, and nonselective dopamine receptor agonists.
Reinforcement sensitivity changed with D1-type and nonselective dopamine agonists but not the D2-type agonist quinpirole, indicating reward sensitivity depends more on D1-like than D2-like receptors.
01Research in Context
What this study did
Scientists gave rats three kinds of dopamine drugs.
Some drugs hit D1 receptors, some hit D2, and some hit both.
The rats pressed levers for sugar water while the team watched how hard they worked and how fast they quit.
What they found
D1 drugs changed how much the sugar was worth.
Low doses made the rats work harder.
High doses made them spin in circles and stop pressing.
D2 drugs only slowed the rats down; the sugar still felt just as good.
How this fits with other research
Spriggs et al. (2016) looked at the kids on meds and saw most behavior drop.
That fits: D1-type meds can cut problem behavior by dulling reward value.
Cohen (1986) found drugs don’t act like extinction.
This study shows why: D1 changes reward, not just response strength.
Hake et al. (1983) paired Dexedrine with self-control training and got extra gains.
Their combo worked because the drug (D1 action) set the stage and ABA did the rest.
Why it matters
If a client starts a dopamine med, watch for two things.
First, the reward value of your reinforcers may shift.
Second, high doses can bring odd motor side effects that look like non-compliance.
Adjust your reinforcer menu and re-run your FA after any dose change.
How dopamine receptors shape reinforcement sensitivity
Dopamine receptors are grouped into D1-like and D2-like families. Sensitivity to reinforcement describes how sharply behavior allocates to richer versus leaner sources of reward, often quantified with the generalized matching law using sensitivity and bias parameters.
Pharmacological agonists let researchers probe which receptor family drives changes in that sensitivity, by selectively stimulating D1-type or D2-type receptors and watching how choice and response allocation shift.
What the study found
Rats received the partial D1-type agonist SKF38393, the selective D2-type agonist quinpirole, and the nonselective agonist apomorphine at low, moderate, and high doses. Reinforcement sensitivity changed dose-dependently with SKF38393 and apomorphine but not with quinpirole.
Bias shifted only at the high dose of apomorphine, and response rates dropped at higher doses of the D1 and nonselective agonists, likely from competing stereotyped behavior. Overall, reward sensitivity was affected more strongly by D1-like than D2-like receptors.
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After any med change, probe your strongest reinforcer with a quick progressive-ratio test to see if it still packs the same punch.
02At a glance
03Original abstract
Dose-dependent changes in sensitivity to reinforcement were found when rats were treated with low, moderate, and high doses of the partial dopamine D1-type receptor agonist SKF38393 and with the nonselective dopamine agonist apomorphine, but did not change when rats were treated with similar doses of the selective dopamine D2-type receptor agonist quinpirole. Estimates of bias did not differ significantly across exposure to SKF38393 or quinpirole, but did change significantly at the high dose of apomorphine. Estimates of goodness of fit (r2) did not change significantly during quinpirole exposure. Poor goodness of fit was obtained for the high doses of SKF38393 and apomorphine. Decrements in absolute rates of responding were observed at the high dose of quinpirole and at the moderate and high doses of SKF38393 and apomorphine. Changes in r2 and absolute responding may be due to increases in stereotyped behavior during SKF38393 and apomorphine exposure that, in contrast to quinpirole, were distant from the response lever. The present data provide evidence that sensitivity to reward is affected more strongly by dopamine D1-like receptors rather than D2-like receptors, consistent with evidence from other studies investigating consummatory dopamine behavior and the tonic/phasic dopamine hypothesis.
Journal of the experimental analysis of behavior, 2005 · doi:10.1901/jeab.2005.82-04