VA Boston Healthcare System, Brockton, MA, USA.
Department of Psychiatry, Boston University School of Medicine, Boston, MA, USA.
Cogn Affect Behav Neurosci. 2019 Jun;19(3):523-536. doi: 10.3758/s13415-018-00687-8.
Recent evidence suggests that the human hippocampus-known primarily for its involvement in episodic memory-plays a role in a host of motivationally relevant behaviors, including some forms of value-based decision-making. However, less is known about the role of the hippocampus in value-based learning. Such learning is typically associated with a striatal system, yet a small number of studies, both in human and nonhuman species, suggest hippocampal engagement. It is not clear, however, whether this engagement is necessary for such learning. In the present study, we used both functional MRI (fMRI) and lesion-based neuropsychological methods to clarify hippocampal contributions to value-based learning. In Experiment 1, healthy participants were scanned while learning value-based contingencies (whether players in a "game" win money) in the context of a probabilistic learning task. Here, we observed recruitment of the hippocampus, in addition to the expected ventral striatal (nucleus accumbens) activation that typically accompanies such learning. In Experiment 2, we administered this task to amnesic patients with medial temporal lobe damage and to healthy controls. Amnesic patients, including those with damage circumscribed to the hippocampus, failed to acquire value-based contingencies, thus confirming that hippocampal engagement is necessary for task performance. Control experiments established that this impairment was not due to perceptual demands or memory load. Future research is needed to clarify the mechanisms by which the hippocampus contributes to value-based learning, but these findings point to a broader role for the hippocampus in goal-directed behaviors than previously appreciated.
最近的证据表明，人类海马体——主要因其在情景记忆中的参与而闻名——在一系列与动机相关的行为中发挥作用，包括某些形式的基于价值的决策。然而，关于海马体在基于价值的学习中的作用知之甚少。这种学习通常与纹状体系统有关，但一些在人类和非人类物种中的研究表明海马体的参与。然而，尚不清楚这种参与对于这种学习是否是必要的。在本研究中，我们使用功能磁共振成像（fMRI）和基于损伤的神经心理学方法来阐明海马体对基于价值的学习的贡献。在实验 1 中，健康参与者在进行概率学习任务的同时，扫描学习基于价值的关联（在“游戏”中玩家是否赢得金钱）。在这里，我们观察到海马体的招募，除了通常伴随这种学习的预期腹侧纹状体（伏隔核）激活。在实验 2 中，我们向内侧颞叶损伤的健忘症患者和健康对照组施行了这项任务。健忘症患者，包括那些海马体损伤局限于海马体的患者，未能习得基于价值的关联，从而证实了海马体的参与对于任务表现是必要的。对照实验确立了这种损伤不是由于感知需求或记忆负荷造成的。需要进一步的研究来阐明海马体有助于基于价值的学习的机制，但这些发现表明，海马体在目标导向行为中的作用比以前认识到的更为广泛。
