Spatial Learning and Action Planning in a Prefrontal Cortical Network Model

The interplay between hippocampus and prefrontal cortex (PFC) is fundamental to spatial cognition. Complementing hippocampal place coding, prefrontal representations provide more abstract and hierarchically organized memories suitable for decision making. We model a prefrontal network mediating distributed information processing for spatial learning and action planning. Specific connectivity and synaptic adaptation principles shape the recurrent dynamics of the network arranged in cortical minicolumns. We show how the PFC columnar organization is suitable for learning sparse topological-metrical representations from redundant hippocampal inputs. The recurrent nature of the network supports multilevel spatial processing, allowing structural features of the environment to be encoded. An activation diffusion mechanism spreads the neural activity through the column population leading to trajectory planning. The model provides a functional framework for interpreting the activity of PFC neurons recorded during navigation tasks. We illustrate the link from single unit activity to behavioral responses. The results suggest plausible neural mechanisms subserving the cognitive “insight” capability originally attributed to rodents by Tolman & Honzik. Our time course analysis of neural responses shows how the interaction between hippocampus and PFC can yield the encoding of manifold information pertinent to spatial planning, including prospective coding and distance-to-goal correlates.

海马体（hippocampus）与前额叶皮层（prefrontal cortex，PFC）之间的相互作用，是空间认知的核心基础。与海马体的位置编码形成互补，前额叶皮层所表征的记忆更为抽象且具备层级化组织结构，适用于决策过程。本研究构建了一个前额叶皮层网络模型，该网络负责介导空间学习与动作规划中的分布式信息处理。特定的连接模式与突触适应原则，塑造了排列为皮层微柱（cortical minicolumns）的该网络的循环动力学特性。本研究阐明了前额叶皮层的柱状组织如何适配于从冗余的海马体输入中学习稀疏的拓扑-度量表征。该网络的循环特性支持多层级空间处理过程，使得环境的结构特征能够被编码。一种激活扩散机制可将神经活动传递至整个微柱群体，进而实现轨迹规划。该模型为解释导航任务中记录的前额叶皮层神经元活动提供了功能性框架。本研究阐释了从单神经元单位活动到行为反应之间的关联。研究结果提示，存在合理的神经机制支撑认知顿悟能力——该能力最初由托尔曼（Tolman）与洪齐克（Honzik）归属于啮齿类动物。本研究对神经反应的时间进程分析表明，海马体与前额叶皮层之间的相互作用如何生成与空间规划相关的多元信息编码，包括前瞻性编码以及与目标距离相关的表征。