Papale Andrew E, Brown Vanessa M, Ianni Angela M, Hallquist Michael N, Luna Beatriz, Dombrovski Alexandre Y
Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA.
Department of Psychology, Emory University, Atlanta, GA, USA.
bioRxiv. 2025 Mar 13:2025.03.12.642890. doi: 10.1101/2025.03.12.642890.
Hippocampal maps and ventral prefrontal cortex (vPFC) value and goal representations support foraging in continuous spaces. How might hippocampal-vPFC interactions control the balance between behavioral exploration and exploitation? Using fMRI and reinforcement learning modeling, we investigated vPFC and hippocampal responses as humans explored and exploited a continuous one-dimensional space, with out-of-session and out-of-sample replication. The spatial distribution of rewards, or value landscape, modulated activity in the hippocampus and default network vPFC subregions, but not in ventrolateral prefrontal control subregions or medial orbitofrontal limbic subregions. While prefrontal default network and hippocampus displayed higher activity in less complex, easy-to-exploit value landscapes, vPFC-hippocampal connectivity increased in uncertain landscapes requiring exploration. Further, synchronization between prefrontal default network and posterior hippocampus scaled with behavioral exploration. Considered alongside electrophysiological studies, our findings suggest that locations to be explored are identified through coordinated activity binding prefrontal default network value representations to posterior hippocampal maps.
海马体图谱以及腹侧前额叶皮质（vPFC）的价值和目标表征有助于在连续空间中觅食。海马体与腹侧前额叶皮质之间的相互作用是如何控制行为探索与利用之间的平衡的呢？我们使用功能磁共振成像（fMRI）和强化学习模型，研究了人类在探索和利用连续一维空间时腹侧前额叶皮质和海马体的反应，并进行了会话外和样本外复制。奖励的空间分布，即价值景观，调节了海马体和默认网络腹侧前额叶皮质子区域的活动，但未调节腹外侧前额叶控制子区域或内侧眶额边缘子区域的活动。虽然前额叶默认网络和海马体在不太复杂、易于利用的价值景观中表现出更高的活动，但在需要探索的不确定景观中，腹侧前额叶皮质与海马体之间的连接性增加。此外，前额叶默认网络与海马体后部之间的同步与行为探索成比例。结合电生理学研究来看，我们的研究结果表明，通过将前额叶默认网络价值表征与海马体后部图谱结合的协调活动，可以识别出有待探索的位置。
