Previous Cocaine Exposure Makes Rats Hypersensitive to Both Delay and Reward Magnitude Export

@article{citeulike:1024833, abstract = {Animals prefer an immediate over a delayed reward, just as they prefer a large over a small reward. Exposure to psychostimulants causes long-lasting changes in structures critical for this behavior and might disrupt normal time-discounting performance. To test this hypothesis, we exposed rats to cocaine daily for 2 weeks (30 mg/kg, i.p.). Approximately 6 weeks later, we tested them on a variant of a time-discounting task, in which the rats responded to one of two locations to obtain reward while we independently manipulated the delay to reward and reward magnitude. Performance did not differ between cocaine-treated and saline-treated (control) rats when delay lengths and reward magnitudes were equal at the two locations. However, cocaine-treated rats were significantly more likely to shift their responding when we increased the delay or reward size asymmetrically. Furthermore, they were slower to respond and made more errors when forced to the side associated with the lower value. We conclude that previous exposure to cocaine makes choice behavior hypersensitive to differences in the time to and size of available rewards, consistent with a general effect of cocaine exposure on reward valuation mechanisms. 10.1523/JNEUROSCI.4080-06.2007}, author = {Roesch, Matthew R. and Takahashi, Yuji and Gugsa, Nishan and Bissonette, Gregory B. and Schoenbaum, Geoffrey}, citeulike-article-id = {1024833}, citeulike-linkout-0 = {http://dx.doi.org/10.1523/JNEUROSCI.4080}, citeulike-linkout-1 = {http://www.jneurosci.org/cgi/content/abstract/27/1/245}, comment = {* rat behavioral study examining the effect of cocaine exposure on sensitivity to changes in reward delay and magnitude * rats exposed to cocaine daily for two weeks, then tested 6 weeks later * rats tested in a odor discrimination task (forced choice), with a third odor indicating availability of both rewards (free choice) * treatment groups did not differ if rewards were equal in delay or magnitude, but cocaine treated rats were quicker to shift to the other reward as delay was increased or reward on the alternative side was increased * note that the differences between the treatment groups went away as the delay lengths or reward sizes were increased * authors conclude that cocaine causes impulsive behavior by affecting the sensitivity to both delay and reward size}, day = {3}, doi = {10.1523/JNEUROSCI.4080}, journal = {J. Neurosci.}, keywords = {\_note, behavior, cocaine, discounting, rat, reward}, month = {January}, number = {1}, pages = {245--250}, posted-at = {2007-01-04 14:26:24}, priority = {2}, title = {Previous Cocaine Exposure Makes Rats Hypersensitive to Both Delay and Reward Magnitude}, url = {http://dx.doi.org/10.1523/JNEUROSCI.4080}, volume = {27}, year = {2007} }

TY - JOUR ID - citeulike:1024833 L3 - citeulike-article-id:1024833 N2 - Animals prefer an immediate over a delayed reward, just as they prefer a large over a small reward. Exposure to psychostimulants causes long-lasting changes in structures critical for this behavior and might disrupt normal time-discounting performance. To test this hypothesis, we exposed rats to cocaine daily for 2 weeks (30 mg/kg, i.p.). Approximately 6 weeks later, we tested them on a variant of a time-discounting task, in which the rats responded to one of two locations to obtain reward while we independently manipulated the delay to reward and reward magnitude. Performance did not differ between cocaine-treated and saline-treated (control) rats when delay lengths and reward magnitudes were equal at the two locations. However, cocaine-treated rats were significantly more likely to shift their responding when we increased the delay or reward size asymmetrically. Furthermore, they were slower to respond and made more errors when forced to the side associated with the lower value. We conclude that previous exposure to cocaine makes choice behavior hypersensitive to differences in the time to and size of available rewards, consistent with a general effect of cocaine exposure on reward valuation mechanisms. 10.1523/JNEUROSCI.4080-06.2007 IS - 1 JF - J. Neurosci. EP - 250 TI - Previous Cocaine Exposure Makes Rats Hypersensitive to Both Delay and Reward Magnitude VL - 27 SP - 245 KW - _note KW - behavior KW - cocaine KW - discounting KW - rat KW - reward N1 - * rat behavioral study examining the effect of cocaine exposure on sensitivity to changes in reward delay and magnitude * rats exposed to cocaine daily for two weeks, then tested 6 weeks later * rats tested in a odor discrimination task (forced choice), with a third odor indicating availability of both rewards (free choice) * treatment groups did not differ if rewards were equal in delay or magnitude, but cocaine treated rats were quicker to shift to the other reward as delay was increased or reward on the alternative side was increased * note that the differences between the treatment groups went away as the delay lengths or reward sizes were increased * authors conclude that cocaine causes impulsive behavior by affecting the sensitivity to both delay and reward size AU - Roesch, Matthew AU - Takahashi, Yuji AU - Gugsa, Nishan AU - Bissonette, Gregory AU - Schoenbaum, Geoffrey PY - 2007/01/03/ UR - http://dx.doi.org/10.1523/JNEUROSCI.4080 ER -