Bezzina G, Cheung T H C, Body S, Deakin J F W, Anderson I M, Bradshaw Chris M, Szabadi E
Psychopharmacology Section, Division of Psychiatry, University of Nottingham, Nottingham, UK.
Behav Pharmacol. 2009 Sep;20(5-6):437-46. doi: 10.1097/FBP.0b013e3283305e4d.
Recent evidence suggests that the subthalamic nucleus (STN) is involved in regulating the incentive value of food reinforcers. The objective of this study was to examine the effect of lesions of the STN on intertemporal choice (choice between reinforcers differing in size and delay). Rats with bilateral quinolinic acid-induced lesions of the STN (n = 15) or sham lesions (n = 14) were trained in a discrete-trials progressive delay schedule to press levers A and B for a sucrose solution. Responses on A delivered 50 microl of the solution after a delay d(A); responses on B delivered 100 microl after a delay d(B). d(B) increased across blocks of trials; d(A) was manipulated across phases of the experiment. Indifference delay, d(B(50)) (value of d(B) corresponding to 50% choice of B), was estimated for each rat in each phase, and linear indifference functions (d(B(50)) vs. d(A)) were derived. The STN-lesioned group showed a flatter slope of the indifference function (implying higher instantaneous reinforcer values) than the sham-lesioned group; the intercepts did not differ between the groups. The results agree with recent evidence for a role of the STN in incentive value. Unlike some earlier studies, these results do not indicate a role of the STN in delay discounting.
近期证据表明，丘脑底核（STN）参与调节食物强化物的激励价值。本研究的目的是检验STN损伤对跨期选择（在大小和延迟不同的强化物之间进行选择）的影响。对双侧经喹啉酸诱导造成STN损伤的大鼠（n = 15）或假损伤大鼠（n = 14）进行离散试验渐进延迟训练，使其按压杠杆A和B以获取蔗糖溶液。对A的反应在延迟d(A)后提供50微升溶液；对B的反应在延迟d(B)后提供100微升溶液。d(B)在各试验组中增加；d(A)在实验各阶段进行操控。为每只大鼠在每个阶段估计无差异延迟d(B(50))（对应50%选择B的d(B)值），并得出线性无差异函数（d(B(50))与d(A)）。与假损伤组相比，STN损伤组的无差异函数斜率更平缓（意味着即时强化物价值更高）；两组的截距无差异。这些结果与近期关于STN在激励价值中作用的证据一致。与一些早期研究不同，这些结果并未表明STN在延迟折扣中起作用。
