Krembil Research Institute, University Health Network, Toronto, ON, Canada M5T 2S8.
Psychology Department, University of Toronto, Toronto, ON, Canada M5S 3G3; Rotman Research Institute, Toronto, ON, Canada M6A 2E1.
Neuropsychologia. 2018 Feb;110:26-36. doi: 10.1016/j.neuropsychologia.2017.08.014. Epub 2017 Aug 10.
Individuals with medial temporal lobe epilepsy (mTLE) are poor at recalling vivid details from autobiographical memories (AM), instead retrieving gist-like schematic memories. Recent research has suggested that this impoverished recall in comparison to controls may reflect (1) differential engagement of anterior vs posterior regions of the hippocampus (HC) and/or (2) differences between the engagement of the HC vs the ventromedial prefrontal cortex (vmPFC). Here we examined these hypotheses by comparing connectivity amongst hippocampal regions and between vmPFC and other brain regions during construction (retrieval of a particular event) vs elaboration (retrieval of perceptual detail) phases of AM recall in 12 individuals with left mTLE and 12 matched controls. Whereas functional connectivity amongst hippocampal regions changed from AM construction to elaboration in controls, the pattern of intra-hippocampal connectivity was unvarying in patients. Furthermore, patterns of connectivity from the vmPFC differed between phases in distinct ways in the two groups of participants. In patients, vmPFC activation was correlated with other prefrontal and lateral temporal cortices during construction and with visual-perceptual cortices during elaboration. While controls did not show a difference in whole-brain connectivity, they did uniquely show a dynamic shift from vmPFC connectivity to anterior HC during construction and to posterior HC during elaboration. Together, these findings suggest that impoverished AM recall in mTLE is a consequence of reduced activation and flexibility of bilateral hippocampal networks and greater reliance on neocortical contributions to memory retrieval.
内侧颞叶癫痫(mTLE)患者在回忆自传体记忆(AM)中的生动细节方面表现不佳,相反,他们会提取出梗概式的记忆。最近的研究表明,与对照组相比,这种记忆的匮乏可能反映了(1)海马体(HC)的前区和后区的参与程度不同,和/或(2)HC 与腹内侧前额叶皮质(vmPFC)的参与程度之间的差异。在这里,我们通过比较 12 名左侧 mTLE 患者和 12 名匹配对照者在 AM 回忆的构建(特定事件的检索)和阐述(感知细节的检索)阶段期间,HC 内和 vmPFC 与其他脑区之间的连接,来检验这些假设。在对照组中,海马体区域之间的功能连接从 AM 构建阶段到阐述阶段发生了变化,而患者的内海马体连接模式则保持不变。此外,vmPFC 与其他前额叶和外侧颞叶皮质之间的连接模式在两个组的参与者中以不同的方式在不同的阶段发生变化。在患者中,vmPFC 的激活与构建期间的其他前额叶和外侧颞叶皮质以及阐述期间的视觉感知皮质相关。虽然对照组在全脑连接方面没有差异,但它们确实表现出独特的动态转变,即从 vmPFC 连接到构建期间的前 HC,以及到阐述期间的后 HC。总的来说,这些发现表明,mTLE 患者的 AM 记忆匮乏是由于双侧海马体网络的激活和灵活性降低,以及对新皮质在记忆检索中的贡献的依赖增加所致。
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