Inserm, U1077, Caen, France.
Brain Cogn. 2012 Oct;80(1):111-25. doi: 10.1016/j.bandc.2012.05.004. Epub 2012 Jun 16.
Remembering the past and envisioning the future are at the core of one's sense of identity. Neuroimaging studies investigating the neural substrates underlying past and future episodic events have been growing in number. However, the experimental paradigms used to select and elicit episodic events vary greatly, leading to disparate results, especially with respect to the laterality and antero-posterior localization of hippocampal and adjacent medial temporal activations (i.e., parahippocampal, entorhinal and perirhinal cortices, amygdala). Although a central concern in today's literature, the issue of hippocampal and medial temporal lobe laterality and antero-posterior segregation in past and future episodic events has not yet been addressed extensively. Using the activation likelihood estimation (ALE) procedure (Turkeltaub, Eden, Jones, & Zeffiro, 2002), we performed a meta-analysis of hippocampal and adjacent medial temporal coordinates extracted from neuroimaging studies examining past remembering and future envisioning. We questioned whether methodological choices could influence the laterality of activations, namely (1) the type of cue used (generic vs. specific), (2) the type of task performed (recognition vs. recall/imagine), (3) the nature of the information retrieved (episodic vs. "strictly" episodic events) and (4) the age of participants. We consider "strictly" episodic events as events which are not only spatio-temporally unique and personal like episodic events, but are also associated with contextual and phenomenological details. These four factors were compared two-by-two, generating eight whole-brain statistical maps. Results indicate that (1) specific cues tend to activate more the right anterior hippocampus compared to the use of generic cues, (2) recall/imagine tasks tend to recruit more the left posterior parahippocampal gyrus compared to recognition tasks, (3) (re/pre)experiencing strictly episodic events tends to activate more the bilateral posterior hippocampus compared to episodic events and (4) older subjects tend to activate more the right anterior hippocampus compared to younger subjects. Importantly, our results stress that strictly episodic events triggered by specific cues elicit greater left posterior hippocampal activation than episodic events triggered by specific cues. These findings suggest that such basic methodological choices have an impact on the conclusions reached regarding past and future (re/pre)experiencing and their neural substrates.
记住过去和想象未来是一个人身份认同感的核心。越来越多的神经影像学研究调查了过去和未来情景事件的神经基础。然而，用于选择和引发情景事件的实验范式差异很大，导致结果不一致，尤其是在海马体和相邻的内侧颞叶激活的左右侧和前后定位（即，旁海马体、内嗅皮质和边缘回皮质、杏仁核）方面。尽管这是当今文献的一个核心关注点，但过去和未来情景事件中海马体和内侧颞叶的左右侧和前后分离问题尚未得到广泛解决。使用激活似然估计（ALE）程序（Turkeltaub、Eden、Jones 和 Zeffiro，2002），我们对检查过去记忆和未来想象的神经影像学研究中提取的海马体和相邻内侧颞叶坐标进行了荟萃分析。我们质疑方法学选择是否会影响激活的左右侧，即：（1）使用的提示类型（通用与特定）；（2）执行的任务类型（识别与回忆/想象）；（3）检索信息的性质（情景与“严格”情景事件）；（4）参与者的年龄。我们将“严格”情景事件定义为不仅在时空上具有独特性和个人性，而且与情境和现象学细节相关的事件。这四个因素两两比较，生成了八个全脑统计图谱。结果表明：（1）与使用通用提示相比，特定提示更倾向于激活右侧前海马体；（2）与识别任务相比，回忆/想象任务更倾向于激活左侧后旁海马回；（3）与情景事件相比，（重新/预先）体验“严格”情景事件更倾向于激活双侧后海马体；（4）与年轻参与者相比，老年参与者更倾向于激活右侧前海马体。重要的是，我们的结果强调，与特定提示引发的情景事件相比，特定提示引发的“严格”情景事件更能激活左侧后海马体。这些发现表明，这些基本方法学选择会对过去和未来（重新/预先）体验及其神经基础的结论产生影响。
