Coutureau Etienne, Killcross Simon
School of Psychology, Cardiff University, PO Box 901, Park Place, Cardiff, CF10 3YG, UK.
Behav Brain Res. 2003 Nov 30;146(1-2):167-74. doi: 10.1016/j.bbr.2003.09.025.
Over the course of extended training, instrumental responding in rats shows a transition from goal-dependent performance to goal-independent performance, as assessed by sensitivity to reward-devaluation induced by taste aversions or specific satiety. It has been suggested that this reflects the gradual dominance of reflexive, habit-based responding over voluntary, goal-directed actions. Previous research suggests that lesions of the medial prefrontal cortex disrupt this interaction between goal-directed and habitual responding. More specifically, whereas lesions of the prelimbic prefrontal cortex appear to disrupt normal goal-directed responding, lesions of the infralimbic prefrontal cortex cause animals to remain goal-directed even after substantial overtraining. The current experiment explored further the nature of this interaction between actions and habits. Rats were given extended training of an instrumental lever press response before bilateral intracerebral cannulae giving access to the infralimbic cortex were implanted. Following further reminder training all animals were given a test of goal sensitivity by specific-satiety devaluation of the instrumental outcome, or a matched reward, prior to extinction tests. Before these tests, half of the animals received bilateral infusions of muscimol into the infralimbic cortex, and the remainder, control vehicle infusions. As expected after extended instrumental training, control-infused animals showed habitual performance that was not selectively influenced by devaluation of the instrumental outcome. In contrast, animals receiving temporary inactivation of the infralimbic cortex by muscimol showed selective sensitivity to devaluation of the instrumental outcome, indicating a reinstatement of goal-directed responding in these animals. This suggests that the development of habitual responding reflects the active inhibition of goal-directed responses that are mediated by action-outcome associations.
在长期训练过程中，大鼠的工具性反应表现出从依赖目标的行为向不依赖目标的行为转变，这是通过对味觉厌恶或特定饱腹感诱导的奖励贬值的敏感性来评估的。有人认为，这反映了基于反射的习惯性反应逐渐超过了自愿的、目标导向的行为。先前的研究表明，内侧前额叶皮质的损伤会破坏目标导向和习惯性反应之间的这种相互作用。更具体地说，虽然边缘前皮质的损伤似乎会破坏正常的目标导向反应，但边缘下前额叶皮质的损伤会导致动物即使在大量过度训练后仍保持目标导向。当前的实验进一步探讨了这种行为与习惯之间相互作用的本质。在植入双侧脑内套管以进入边缘下皮质之前，先对大鼠进行工具性杠杆按压反应的长期训练。在进一步的提示训练之后，在消退测试之前，所有动物都通过对工具性结果或匹配奖励进行特定饱腹感贬值来进行目标敏感性测试。在这些测试之前，一半的动物接受双侧向边缘下皮质注入蝇蕈醇，其余的接受对照载体注入。正如长期工具性训练后所预期的那样，接受对照注入的动物表现出习惯性行为，且不受工具性结果贬值的选择性影响。相比之下，接受蝇蕈醇使边缘下皮质暂时失活的动物对工具性结果贬值表现出选择性敏感性，这表明这些动物恢复了目标导向反应。这表明习惯性反应的发展反映了由动作-结果关联介导的目标导向反应的主动抑制。
