前额叶皮层和纹状体间功能性连接的量化分析

Quantitative Analysis of Functional Connectivity between Prefrontal Cortex and Striatum

奖励预测对于大脑的学习记忆、行为决策等高级认知功能具有至关重要的意义。前额叶皮层(Prefrontal Cortex,PFC)和纹状体(Striatum)是大脑中的两个重要脑区,以往的研究发现,前额叶皮层和纹状体中的神经元都参与了对奖励信息的编码,然而,对于这两个脑区之间信息交流、相互影响的具体方式仍然不够明确。为了研究这一问题,在对猴子进行非对称奖励预测实验的过程中,用多通道电极同时记录了其前额叶皮层和纹状体两个部位的局域场电位(Local Field Potentials, LFP)信号。通过计算非线性相互依赖性(Nonlinear Interdependence,NLI)来量化分析前额叶皮层和纹状体之间功能性连接的强度。结果显示,在β频段(15～30 Hz),小水奖励条件下前额叶皮层和纹状体间的功能性连接强度显著高于大水奖励条件下的结果,同时,前额叶皮层和纹状体间不同方向的连接强度也有显著差别。实验结果表明,前额叶皮层中LFP的β频段可能与纹状体神经元的活动有关,并在一定程度上调节猴子在奖励预测过程中的行为。

The prefrontal cortex (PFC) and striatum are two important regions in the brain,which involves in many higher cognitive processes,e.g.,learning,memory,information processing,and inference,decision-making,and so on.Reward prediction is essential for learning behavior and decision-making process in the brain.It is well-known that the neurons in both PFC and striatum are responsible for encoding reward information,and the interplay between the PFC and striatum plays an important role in cognitive processes.However,the specific ways of information exchange between these two brain regions and the interaction between PFC and striatum are still not clearly known.To this end,we records in this work the local field potentials (LFPs) in the lateral PFC and the striatum of two male monkeys,while these monkeys are experimentally performed the sequential paired-association task with the asymmetric reward scheme.And then,the nonlinear interdependence (NLI) measure is computed to quantify the strength of functional connectivity between the PFC and striatum.It is found that the functional connectivity strength between these two brain regions is significantly higher in small reward conditions than that in big ones,which mainly happens in β frequency band.Besides,it is also found via results that there exists significantly greater functional connectivity from the PFC to the striatum than that in opposite direction.This result is consistent with the fact that PFC neurons have direct projections to striatal neurons,while striatal neurons do not project to LPFC neurons directly.This means that PFC neurons could regulate the striatum neurons’ activity to some extent.