Department of Psychology, McGill University, Montreal, Québec, Canada.
Rotman Research Institute, Baycrest Health Sciences Centre, Toronto, Ontario, Canada.
Hippocampus. 2018 Apr;28(4):269-280. doi: 10.1002/hipo.22829. Epub 2018 Jan 24.
The medial temporal lobes (MTL), and more specifically the hippocampus, are critical for forming mental representations of past experiences-autobiographical memories-and for forming other "nonexperienced" types of mental representations, such as imagined scenarios. How the MTL coordinate with other brain areas to create these different types of representations is not well understood. To address this issue, we performed a task-based functional connectivity analysis on a previously published dataset in which fMRI data were collected as participants created different types of mental representations under three conditions. One condition required forming and relating together details from a past event (autobiographical task), another required forming and relating together details of a spatial context (spatial task) and another condition required relating together conceptual/perceptual features of an object (conceptual task). We contrasted the connectivity patterns associated with a functionally defined region in the parahippocampal cortex (PHC) and anatomically defined anterior and posterior hippocampal segments across these tasks. Examining PHC connectivity patterns revealed that the PHC seed was distinctly connected to other MTL structures during the autobiographical task, to posterior parietal regions during the spatial task and to a distributed network of regions for the conceptual task. Examining hippocampal connectivity patterns revealed that the anterior hippocampus was preferentially connected to regions of default mode network during the autobiographical task and to areas implicated in semantic processing for the conceptual task whereas the posterior hippocampus was preferentially connected to medial-posterior regions of the brain during the spatial task. We interpret our findings as evidence that there are MTL-guided networks for forming distinct types of mental representations that align with functional distinctions within the hippocampus.
内侧颞叶（MTL），特别是海马体，对于形成过去经历的心理表象（自传体记忆）以及形成其他“非经验”类型的心理表象，如想象场景，至关重要。MTL 如何与其他大脑区域协调以创建这些不同类型的表象还不是很清楚。为了解决这个问题，我们对之前发表的数据集进行了基于任务的功能连接分析，在该数据集中，当参与者在三种条件下创建不同类型的心理表象时，采集了 fMRI 数据。一种条件要求从过去的事件中形成和关联细节（自传体任务），另一种要求从空间背景中形成和关联细节（空间任务），另一种条件要求从对象的概念/感知特征中形成和关联细节（概念任务）。我们对比了在这些任务中与定义明确的旁海马皮层（PHC）功能区和解剖定义的前海马和后海马段相关的连接模式。检查 PHC 连接模式表明，在自传体任务中，PHC 种子与其他 MTL 结构明显连接，在空间任务中与后顶叶区域连接，在概念任务中与分布式网络区域连接。检查海马连接模式表明，在前海马体在自传体任务中与默认模式网络的区域优先连接，在概念任务中与语义处理相关的区域优先连接，而后海马体在空间任务中与大脑的中后部区域优先连接。我们将这些发现解释为证据，表明存在 MTL 引导的网络，用于形成与海马体内部的功能区别相一致的不同类型的心理表象。
