Araujo, Silvana , Body, Stephanie , Valencia-torres, Lourdes , OLARTE SÁNCHEZ, CRISTIAN MANUEL, Bak, Vicky , William-deakin, John Francis , Anderson, Ian , Bradshaw, Cristopher , Szabadi, Elemer
Si
Behav Brain Res
Article
Científica
3.393
1.795
01/01/2010
000279748600019
Lesions of the orbital prefrontal cortex (OPFC) and the nucleus accumbens core (AcbC) can disrupt performance in inter-temporal choice tasks, possibly by increasing the organism's sensitivity to delay and/or magnitude of reinforcement. This experiment examined whether exposure to an inter-temporal choice would induce neuronal activation in these areas, as indicated by enhanced expression of the Fos protein. Twelve rats were trained to press levers A and B under an adjusting-delay schedule in which a response on A delivered 50 mu l of a sucrose reinforcer after 2 or 18 s, whereas a response on B delivered the same reinforcer after a delay that was adjusted in accordance with the rat's choices. Another 12 rats were trained under a similar schedule in which a response on A delivered an immediate reinforcer of size 20 or 180 mu l, whereas a response on B delivered an immediate reinforcer whose size was adjusted in accordance with the rat's choices. A third group received training under a schedule that did not entail variation of reinforcer size or delay, or choice between reinforcers, and a control group underwent food restriction without behavioural training. Exposure to the adjusting-delay schedule was associated with enhanced Fos expression in both the OPFC and AcbC, whereas exposure to the adjusting-magnitude schedule was associated with enhanced Fos expression in the OPFC but not the AcbC, compared to the control group. The results are consistent with previous findings that implicated the AcbC and OPFC in delay discounting, and the OPFC in sensitivity to reinforcer size. (C) 2010 Elsevier B.V. All rights reserved.
Nucleus accumbens core; Orbital prefrontal cortex; Fos expression; Inter-temporal choice; Adjusting-delay schedule; Adjusting-magnitude schedule; Delay discounting; Rat