Department of Psychology, Korea University, Seoul, Republic of Korea.
Neurobiol Learn Mem. 2010 Sep;94(2):206-13. doi: 10.1016/j.nlm.2010.05.008. Epub 2010 Jun 2.
Although cholinergic mechanisms have been widely implicated in learning and memory processes, few studies have investigated the specific contribution of hippocampal cholinergic transmission during trace fear conditioning, a form of associative learning involving a temporal gap between two stimuli. Microinfusions of scopolamine, a muscarinic receptor antagonist, into the dorsal hippocampus (DH) produced dose-dependent impairment in the acquisition and expression of a conditioned response (CR) following trace fear conditioning with a tone conditioned stimulus (CS) and a footshock unconditioned stimulus (US) in rats. The same infusions, however, had no effect on delay conditioning, general activity, pain sensitivity or attentional modulation. Moreover, scopolamine infusions attenuated phosphorylation of extracellular signal-regulated kinase (ERK) in the amygdala, indicating that cholinergic signals in the DH are important for trace fear conditioning. Taken together, the current study provides evidence that cholinergic neurotransmission in the DH is essential for the cellular processing of CS-US association in the amygdala when the two stimuli are temporally disconnected.
尽管胆碱能机制已广泛涉及学习和记忆过程，但很少有研究调查在痕迹恐惧条件反射期间海马胆碱能传递的特定贡献，这是一种涉及两个刺激之间时间间隔的联想学习形式。在大鼠中，将毒蕈碱受体拮抗剂东莨菪碱微量注射到背侧海马（DH）中，会导致在使用音调条件刺激（CS）和足底电击非条件刺激（US）进行痕迹恐惧条件反射时，条件反应（CR）的获得和表达产生剂量依赖性损伤。然而，相同的输注对延迟条件反射、一般活动、疼痛敏感性或注意力调节没有影响。此外，东莨菪碱输注可减弱杏仁核中细胞外信号调节激酶（ERK）的磷酸化，表明 DH 中的胆碱能信号对于痕迹恐惧条件反射很重要。总之，本研究提供的证据表明，当两个刺激在时间上断开时，DH 中的胆碱能神经传递对于在杏仁核中 CS-US 关联的细胞处理是必需的。
