Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Korea.
Department of Psychological and Brain Sciences, Dartmouth College, Hanover, NH 03755, USA.
Soc Cogn Affect Neurosci. 2017 Sep 1;12(9):1428-1436. doi: 10.1093/scan/nsx072.
The nucleus accumbens (NAc) shell lies anatomically at a critical intersection within the brain's reward system circuitry, however, its role in voluntary choice behavior remains unclear. Rats with electrolytic lesions in the NAc shell were tested in a novel foraging paradigm. Over a continuous two-week period they freely chose among four nutritionally identical but differently flavored food pellets by pressing corresponding levers. We examined the lesion's effects on three behavioral dynamics components: motivation (when to eat), preference bias (what to choose) and persistence (how long to repeat the same choice). The lesion led to a marked increase in the preference bias: i.e., increased selection of the most-preferred choice option, and decreased selection of the others. We found no effects on any other behavioral measures, suggesting no effect on motivation or choice persistence. The results implicate the NAc shell in moderating the instrumental valuation process by inhibiting excessive bias toward preferred choice options.
伏隔核壳部位于大脑奖励系统回路的一个关键交汇点，然而，它在自愿选择行为中的作用仍不清楚。在一个新的觅食范式中，对伏隔核壳部电解损伤的大鼠进行了测试。在连续两周的时间里，它们通过按压相应的杠杆，自由选择四种营养相同但口味不同的食物丸。我们研究了损伤对三种行为动力学成分的影响：动机（何时进食）、偏好偏差（选择什么）和坚持（重复相同选择的时间长度）。损伤导致偏好偏差明显增加：即增加了对最偏好选择选项的选择，减少了对其他选项的选择。我们没有发现对任何其他行为测量的影响，这表明对动机或选择坚持没有影响。研究结果表明，伏隔核壳部通过抑制对首选选择选项的过度偏见，调节工具性评估过程。
