Chen Hao, Wang Yi-jie, Yang Li, Sui Jian-feng, Hu Zhi-an, Hu Bo
Department of Physiology, College of Basic Medical Sciences, Third Military Medical University, Chongqing 400038, P.R. China.
Sci Rep. 2016 Feb 16;6:20960. doi: 10.1038/srep20960.
Associative learning is thought to require coordinated activities among distributed brain regions. For example, to direct behavior appropriately, the medial prefrontal cortex (mPFC) must encode and maintain sensory information and then interact with the cerebellum during trace eyeblink conditioning (TEBC), a commonly-used associative learning model. However, the mechanisms by which these two distant areas interact remain elusive. By simultaneously recording local field potential (LFP) signals from the mPFC and the cerebellum in guinea pigs undergoing TEBC, we found that theta-frequency (5.0-12.0 Hz) oscillations in the mPFC and the cerebellum became strongly synchronized following presentation of auditory conditioned stimulus. Intriguingly, the conditioned eyeblink response (CR) with adaptive timing occurred preferentially in the trials where mPFC-cerebellum theta coherence was stronger. Moreover, both the mPFC-cerebellum theta coherence and the adaptive CR performance were impaired after the disruption of endogenous orexins in the cerebellum. Finally, association of the mPFC -cerebellum theta coherence with adaptive CR performance was time-limited occurring in the early stage of associative learning. These findings suggest that the mPFC and the cerebellum may act together to contribute to the adaptive performance of associative learning behavior by means of theta synchronization.
联想学习被认为需要分布式脑区之间的协调活动。例如，为了适当地指导行为，内侧前额叶皮质（mPFC）必须编码并维持感觉信息，然后在痕迹眨眼条件反射（TEBC，一种常用的联想学习模型）过程中与小脑相互作用。然而，这两个相距较远的区域相互作用的机制仍然不清楚。通过在接受TEBC的豚鼠中同时记录来自mPFC和小脑的局部场电位（LFP）信号，我们发现，在呈现听觉条件刺激后，mPFC和小脑中的θ频率（5.0 - 12.0赫兹）振荡变得强烈同步。有趣的是，具有适应性定时的条件眨眼反应（CR）优先出现在mPFC - 小脑θ相干性更强的试验中。此外，在破坏小脑中的内源性食欲素后，mPFC - 小脑θ相干性和适应性CR表现均受损。最后，mPFC - 小脑θ相干性与适应性CR表现的关联具有时间限制，发生在联想学习的早期阶段。这些发现表明，mPFC和小脑可能通过θ同步共同作用，以促进联想学习行为的适应性表现。
