What makes slacker rats work harder



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What makes slacker rats work harder
DOI: 10.1038/ NPP.2012.30

Feeding amphetamine to “slacker” rats motivates them to work harder, while “worker” rats slack off if given amphetamine or caffeine. These results, published online this week in Neuropsychopharmacology, may help in explaining why stimulant drugs affect people differently and could have important implications for our understanding the increases in mental fatigue and lack of motivation associated with many psychiatric illnesses, including depression.
Some individuals are more willing to concentrate and exert effort to achieve their goals than others. However, little is known about the brain mechanisms determining how much cognitive effort one will expend in order to reach the best decision, known as the cost/benefit ratio.
Jay Hosking, Catharine Winstanley and colleagues found that rats similarly could be classified into those that would expend high or low degrees of cognitive effort to obtain food rewards, termed “worker” and “slacker” rats, respectively. When presented with cognitively challenging tasks that were rewarded with food pellets, the “worker” rats were less motivated by caffeine or amphetamine, whereas “slacker” rats were more willing to try harder tasks if given either substance. The authors conclude that rats, like humans, are sensitive to the cognitive effort involved in decision making, and that these baseline differences can influence response to psychostimulants.

Author contacts:
Jay Hosking (University of British Columbia, Vancouver, Canada)
Tel: +1 604 723 6857; E-mail: jayhosking@psych.ubc.ca
Catharine Winstanley (University of British Columbia, Vancouver, Canada)
Tel: +1 778 846 8908; E-mail: cwinstanley@psych.ubc.ca

Editorial contact for Neuropsychopharmacology:
Natalie Marler (Neuropsychopharmacology, Brentwood, TN, USA)
Tel: +1 615 324 2371; E-mail: nmarler@acnp.org


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