Unit on the Neurobiology of Affective Memory, National Institute of Mental Health, Convent Drive, Bethesda, MD 20892, USA; Department of Neurobiology, University of Alabama at Birmingham, University Boulevard, Birmingham, AL 35294, USA.
Unit on the Neurobiology of Affective Memory, National Institute of Mental Health, Convent Drive, Bethesda, MD 20892, USA.
Curr Biol. 2024 Apr 8;34(7):1549-1560.e3. doi: 10.1016/j.cub.2024.02.037. Epub 2024 Mar 7.
The successful pursuit of goals requires the coordinated execution and termination of actions that lead to positive outcomes. This process relies on motivational states that are guided by internal drivers, such as hunger or fear. However, the mechanisms by which the brain tracks motivational states to shape instrumental actions are not fully understood. The paraventricular nucleus of the thalamus (PVT) is a midline thalamic nucleus that shapes motivated behaviors via its projections to the nucleus accumbens (NAc) and monitors internal state via interoceptive inputs from the hypothalamus and brainstem. Recent studies indicate that the PVT can be subdivided into two major neuronal subpopulations, namely PVT and PVT, which differ in genetic identity, functionality, and anatomical connectivity to other brain regions, including the NAc. In this study, we used fiber photometry to investigate the in vivo dynamics of these two distinct PVT neuronal types in mice performing a foraging-like behavioral task. We discovered that PVT and PVT neurons encode the execution and termination of goal-oriented actions, respectively. Furthermore, activity in the PVT neuronal population mirrored motivation parameters such as vigor and satiety. Similarly, PVT neurons also mirrored some of these parameters, but to a much lesser extent. Importantly, these features were largely preserved when activity in PVT projections to the NAc was selectively assessed. Collectively, our results highlight the existence of two parallel thalamo-striatal projections that participate in the dynamic regulation of goal pursuits and provide insight into the mechanisms by which the brain tracks motivational states to shape instrumental actions.
成功追求目标需要协调执行和终止导致积极结果的行动。这个过程依赖于受内部驱动因素（如饥饿或恐惧）引导的动机状态。然而，大脑跟踪动机状态以塑造工具性行动的机制尚未完全理解。丘脑室旁核（PVT）是一个中线丘脑核，通过向伏隔核（NAc）的投射来塑造动机行为，并通过来自下丘脑和脑干的内脏感觉输入来监测内部状态。最近的研究表明，PVT 可以细分为两个主要的神经元亚群，即 PVT 和 PVT，它们在遗传身份、功能和与其他脑区（包括 NAc）的解剖连接上存在差异。在这项研究中，我们使用光纤光度法在执行类似觅食的行为任务的小鼠中研究了这两种不同的 PVT 神经元类型的体内动力学。我们发现，PVT 和 PVT 神经元分别编码目标导向行动的执行和终止。此外，PVT 神经元群体的活动反映了动机参数，如活力和饱腹感。同样，PVT 神经元也反映了其中的一些参数，但程度要小得多。重要的是，当选择性评估 PVT 投射到 NAc 的活动时，这些特征在很大程度上得以保留。总的来说，我们的研究结果强调了存在两条平行的丘脑-纹状体投射，它们参与了目标追求的动态调节，并为大脑跟踪动机状态以塑造工具性行动的机制提供了深入的了解。
