Psychopharmacology Section, Division of Psychiatry, University of Nottingham, Room B109, Medical School, Queen's Medical Centre, Nottingham, NG7 2UH, UK.
Psychopharmacology (Berl). 2012 Jan;219(2):271-83. doi: 10.1007/s00213-011-2459-1. Epub 2011 Sep 6.
There is evidence that the core of the nucleus accumbens (AcbC) is involved in inter-temporal choice behaviour.
A new behavioural protocol was used to examine the effect of destruction of the AcbC on delay discounting in inter-temporal choice schedules in rats.
Rats with excitotoxic lesions of the AcbC or sham lesions made repeated choices on an adjusting-delay schedule between a smaller reinforcer (A) that was delivered immediately and a larger reinforcer (B) that was delivered after a delay which increased or decreased depending on the subject's choices. In two phases of the experiment, reinforcer sizes were selected which enabled theoretical parameters expressing delay discounting and sensitivity to reinforcer size to be estimated from the ratio of the indifference delays (i.e. the quasi-stable values of the adjusting delay seen after extended training) obtained in the two phases.
In both groups, indifference delays were shorter when the sizes of A and B were 14 and 25 μl than when they were 25 and 100 μl of a 0.6 M sucrose solution. Indifference delays were shorter in AcbC-lesioned than in sham-lesioned rats. Estimates of delay discounting rate based on the ratio of the indifference delays were lower in the AcbC-lesioned than in the sham-lesioned rats. The size sensitivity parameter did not differ between the groups. Adjusting delays in successive blocks of trials were analysed using Fourier transform. The period corresponding to the dominant frequency of the power spectrum and power within the dominant frequency band did not differ between the groups.
Destruction of the AcbC increased the rate of delay discounting.
有证据表明，伏隔核（AcbC）的核心参与了跨时选择行为。
使用新的行为协议来研究损毁 AcbC 对大鼠跨时选择方案中延迟折扣的影响。
使用兴奋性 AcbC 损伤或假损伤的大鼠，在一个调整延迟时间表上进行重复选择，较小的强化物（A）立即给予，较大的强化物（B）在延迟后给予，延迟时间取决于被试的选择。在实验的两个阶段，选择强化物的大小，使表示延迟折扣和对强化物大小敏感性的理论参数可以从两个阶段获得的无差异延迟（即调整延迟的准稳定值）的比率中估计出来。
在两组中，当 A 和 B 的大小分别为 14 和 25 μl 时，无差异延迟比当它们分别为 25 和 100 μl 时更短。AcbC 损伤组的无差异延迟比假损伤组更短。基于无差异延迟比率的延迟折扣率估计值在 AcbC 损伤组中低于假损伤组。大小敏感性参数在两组之间没有差异。使用傅里叶变换分析连续试验块中的调整延迟。功率谱的主导频率对应的周期和主导频带内的功率在两组之间没有差异。
损毁 AcbC 增加了延迟折扣的速度。
