Psychology Department, University of Washington, Seattle, Washington, USA.
Graduate Program in Neuroscience, University of Washington, Seattle, Washington, USA.
Hippocampus. 2021 Jul;31(7):690-700. doi: 10.1002/hipo.23306. Epub 2021 Jan 28.
Important interactions between memory and decision-making processes are required to maintain high-levels of spatial working memory task performance. Past research reveals that the medial prefrontal cortex (mPFC) and hippocampus (HPC) are both vital structures involved in these processes. Recent evidence suggests that interactions between these two structures are dynamic and task dependent. However, there exists uncertainty surrounding the specific conditions that recruit mPFC contributions to these tasks, specifically regarding its role in retaining information online during delay periods. To address this issue, we tested rats on a spatial-delayed alternation task in which we utilized a closed-loop optogenetic system to transiently disrupt mPFC activity during different task epochs (delay, choice, return). By analyzing the effects of mPFC disruption on choice accuracy and a deliberative behavior known as vicarious-trial-and-error (VTE), our study revealed several interesting findings regarding the role of the mPFC in spatial-working memory tasks. The main findings include: (a) choice accuracy in the spatial-delayed alternation (SDA) task was impaired when the mPFC was disrupted during the choice epoch and not delay or return epochs, (b) mPFC disruption resulted in a non-epoch specific reduction in VTE occurrence which correlated with impairments in task performance. Taken together, findings from this study suggest that, during spatial decision-making, contributions made by the mPFC are specific to points of deliberation and choice (not delay), and that VTEs are a deliberative behavior which relies on intact mPFC function.
重要的记忆和决策过程之间的相互作用是维持高水平的空间工作记忆任务表现所必需的。过去的研究表明，内侧前额叶皮层（mPFC）和海马体（HPC）都是涉及这些过程的重要结构。最近的证据表明，这两个结构之间的相互作用是动态的，依赖于任务。然而，对于招募 mPFC 对这些任务的贡献的具体条件存在不确定性，特别是关于其在延迟期间在线保留信息的作用。为了解决这个问题，我们在空间延迟交替任务中测试了大鼠，在该任务中，我们利用闭环光遗传学系统在不同的任务时段（延迟、选择、返回）短暂干扰 mPFC 活动。通过分析 mPFC 干扰对选择准确性和一种称为替代性试错（VTE）的深思熟虑行为的影响，我们的研究揭示了关于 mPFC 在空间工作记忆任务中的作用的一些有趣发现。主要发现包括：（a）当 mPFC 在选择时段而不是延迟或返回时段受到干扰时，空间延迟交替（SDA）任务中的选择准确性受损；（b）mPFC 干扰导致 VTE 发生的非时段特异性减少，这与任务表现的损伤相关。总之，这项研究的结果表明，在空间决策过程中，mPFC 的贡献特定于思考和选择（而非延迟）点，而 VTE 是一种依赖于完整的 mPFC 功能的深思熟虑的行为。
