Department of Cognitive and Clinical Neuroscience, Central Institute of Mental Health, University of Heidelberg, Mannheim D-68159, Germany.
Hum Brain Mapp. 2012 Feb;33(2):478-88. doi: 10.1002/hbm.21224. Epub 2011 Mar 24.
Both animal and human studies have identified a critical role of the hippocampus in contextual fear conditioning. In humans mainly functional magnetic resonance imaging has been used. To extend these findings to volumetric properties, 58 healthy participants underwent structural magnetic resonance imaging and participated in a differential fear conditioning paradigm with contextual stimuli. Ratings of emotional valence, arousal, and contingency as well as skin conductance responses (SCRs) were used as indicators of conditioning. Twenty-nine participants with the smallest hippocampal volumes were compared with 29 persons with the largest hippocampal volumes. Persons with larger hippocampal volume (especially on the right side) learned to discriminate between two conditioned contexts, whereas those with small hippocampal volumes did not, as indicated by SCRs. Further analyses showed that these results could not be explained by amygdalar volumes. In contrast, the participant answers on the self-report measures were not significantly influenced by hippocampal or amygdalar, but by total brain volume, suggesting a role of cortical structures in these more cognitive evaluation processes. Reanalysis of the self-report data using partial hippocampal volumes revealed a significant influence of the posterior but not anterior subvolumes, which is in accordance with theories and empirical findings on hippocampal functioning. This study shows the relevance of hippocampal volume for contextual fear conditioning in healthy volunteers and may have important implications for anxiety disorders.
动物和人类研究都确定了海马体在情境性恐惧条件反射中的关键作用。在人类中，主要使用功能磁共振成像。为了将这些发现扩展到体积属性，58 名健康参与者接受了结构磁共振成像，并参与了具有情境刺激的差异恐惧条件反射范式。情绪效价、唤醒和关联性的评分以及皮肤电反应 (SCR) 被用作条件反射的指标。将 29 名海马体体积最小的参与者与 29 名海马体体积最大的参与者进行比较。具有较大海马体体积（特别是右侧）的人学会区分两种条件性环境，而海马体体积较小的人则无法区分，这可以通过 SCR 来证明。进一步的分析表明，这些结果不能用杏仁核体积来解释。相比之下，参与者在自我报告测量中的答案不受海马体或杏仁核的显著影响，但受总脑体积的影响，这表明皮质结构在这些更具认知评估过程中发挥作用。使用部分海马体体积对自我报告数据的重新分析显示，后亚区而不是前亚区的体积有显著影响，这与海马体功能的理论和实证发现一致。这项研究表明海马体体积对健康志愿者的情境性恐惧条件反射的重要性，并且可能对焦虑症有重要意义。
