Galtress Tiffany, Kirkpatrick Kimberly
Department of Psychology, University of York.
Department of Psychology.
Behav Neurosci. 2010 Feb;124(1):26-43. doi: 10.1037/a0018464.
The present series of experiments aimed to pinpoint the source of nucleus accumbens core (AcbC) effects on delay discounting. Rats were trained with an impulsive choice procedure between an adjusting smaller sooner reward and a fixed larger later reward. The AcbC-lesioned rats produced appropriate choice behavior when the reward magnitude was equal. An increase in reward magnitude resulted in a failure to increase preference for the larger later reward in the AcbC-lesioned rats, whereas a decrease in the larger later reward duration resulted in normal alterations in choice behavior in AcbC-lesioned rats. Subsequent experiments with a peak timing (Experiments 2 and 3) and a behavioral contrast (Experiment 4) indicated that the AcbC-lesioned rats suffered from decreased incentive motivation during changes in reward magnitude (Experiments 2 and 4) and when expected rewards were omitted (Experiments 2 and 3), but displayed intact anticipatory timing of reward delays (Experiments 2 and 3). The results indicate that the nucleus accumbens core is critical for determining the incentive value of rewards, but does not participate in the timing of reward delays.
本系列实验旨在确定伏隔核核心（AcbC）对延迟折扣产生影响的根源。采用冲动选择程序对大鼠进行训练，让其在逐渐调整的较小即时奖励和固定的较大延迟奖励之间做出选择。当奖励量相等时，伏隔核核心受损的大鼠表现出适当的选择行为。奖励量增加时，伏隔核核心受损的大鼠未能增加对较大延迟奖励的偏好，而较大延迟奖励的持续时间缩短时，伏隔核核心受损的大鼠的选择行为出现正常变化。随后进行的峰值时间实验（实验2和3）和行为对比实验（实验4）表明，伏隔核核心受损的大鼠在奖励量变化时（实验2和4）以及预期奖励被省略时（实验2和3），激励动机降低，但在奖励延迟的预期时间方面表现正常（实验2和3）。结果表明，伏隔核核心对于确定奖励的激励价值至关重要，但不参与奖励延迟的计时。
