Departamento de Psicologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Avenida Bandeirantes, 3900; 14049-901, Ribeirão Preto, São Paulo, Brazil.
Behav Brain Res. 2013 Sep 1;252:439-43. doi: 10.1016/j.bbr.2013.06.028. Epub 2013 Jun 21.
The reinforcement omission effects (ROEs) have been attributed to both motivational and attentional consequences of the surprising reinforcement omission. Some studies have been showed amygdala is part of a circuit involved in the ROEs modulation. The view that amygdala lesions interfere with the ROEs is supported by evidence involving amygdala in responses correlated with motivational processes. These processes depend on the operation of separate amygdala areas and their connections with other brain systems. It has been suggested the interaction between the amygdala and the nucleus accumbens (NAC) is important to the modulation of motivational processes. Recent neuroimaging studies in human revealed reward delivery enhances activity of subcortical structures (NAC and amygdala), whereas reward omission reduces the activity in these same structures. The present study aimed to clarify whether the mechanisms related to ROEs depend on NAC. Prior to acquisition training, rats received bilateral excitotoxic lesions of NAC (NAC group) or sham lesions (Sham group). Following postoperative recovery, the rats were trained on a fixed-interval with limited hold signaled schedule of reinforcement. After acquisition of stable performance, the training was changed from 100% to 50% schedule of reinforcement. Both NAC and Sham groups presented the ROEs. However, after nonreinforcement, the response rates of the NAC group were lower than those registered in the Sham group. The performance of the NAC group decreased in the period following nonreinforcement when compared to the period preceding reinforcement omission. These findings suggest the NAC is part of the neural substrate involved in the ROEs modulation.
强化缺失效应（ROEs）归因于令人惊讶的强化缺失的动机和注意力后果。一些研究表明，杏仁核是参与 ROEs 调节的回路的一部分。杏仁核损伤干扰 ROEs 的观点得到了涉及与动机过程相关的杏仁核反应的证据的支持。这些过程取决于单独的杏仁核区域的运作及其与其他大脑系统的连接。有人认为，杏仁核和伏隔核（NAC）之间的相互作用对于调节动机过程很重要。最近的人类神经影像学研究表明，奖励传递增强了皮质下结构（NAC 和杏仁核）的活动，而奖励缺失则降低了这些相同结构的活动。本研究旨在阐明与 ROEs 相关的机制是否取决于 NAC。在获得性训练之前，大鼠接受了 NAC（NAC 组）或假损伤（Sham 组）的双侧兴奋性毒性损伤。术后恢复后，大鼠接受固定间隔有限保持信号强化方案训练。获得稳定表现后，将训练从 100%改为 50%强化方案。NAC 和 Sham 组均表现出 ROEs。然而，在非强化后，NAC 组的反应率低于 Sham 组。与强化缺失之前的时期相比，NAC 组在非强化之后的时期表现出性能下降。这些发现表明 NAC 是参与 ROEs 调节的神经基质的一部分。
