Facultad de Lenguas y Educación, Universidad de Nebrija, Madrid, Spain; Instituto Pluridisciplinar, University Complutense of Madrid, Spain.
Hospital Ruber Internacional, Epilepsy Unit, Neurology Department, Madrid, Spain; University Hospital of Ramón y Cajal, Epilepsy Unit, Neurology Department, Madrid, Spain.
Neurobiol Learn Mem. 2020 Mar;169:107177. doi: 10.1016/j.nlm.2020.107177. Epub 2020 Feb 6.
Mesial temporal lobe epilepsy (mTLE) is a neurological disorder associated with histopathological changes in different subfields of the hippocampus. These alterations have been associated with memory difficulties. In this study, we tested the hypothesis that these difficulties stem on mnemonic discrimination impairment due to a reduced ability to make similar representations more distinct, leading to an increased susceptibility to interference. With this aim, we used a visual mnemonic discrimination task and evaluated the ability of a group of patients with unilateral mTLE, relative to controls, to discriminate between a studied item and a new foil item, as a function of the similarity between them, and of the number of exemplars from a category stored in memory. We found that patients performed worse than controls when the studied item had to be discriminated from a physically similar new object from the same basic-level category. Crucially, reliable differences between groups were observable in the conditions in which more exemplars from a category were held in memory. In the conditions in which the studied item had to be discriminated from a foil from a different basic-level category, there were no differences between groups, with one exception. Neither a general cognitive impairment nor a general memory impairment could account for this pattern of results. Current findings indicate that patients found more difficulties in conditions with higher interference, which poses greater demands for pattern separation. A disruption of pattern separation processes resulting from hippocampal damage provides a reasonable interpretation for these results. Future studies should explore the causal relationship between hippocampal subfields integrity and mnemonic discrimination capacity in mTLE patients.
内侧颞叶癫痫（mTLE）是一种与海马不同亚区的组织病理学变化相关的神经疾病。这些改变与记忆困难有关。在这项研究中，我们假设这些困难源于记忆辨别障碍，由于难以使相似的表示更加独特，导致对干扰的敏感性增加。为此，我们使用了视觉记忆辨别任务，并评估了一组单侧 mTLE 患者相对于对照组的能力，以辨别研究项目和新的干扰项目之间的差异，作为它们之间相似性和记忆中类别中存储的示例数量的函数。我们发现，当研究项目必须与来自同一基本类别物理相似的新对象区分时，患者的表现比对照组差。至关重要的是，当记忆中存储的类别示例更多时，两组之间存在可靠的差异。当研究项目必须与来自不同基本类别的干扰项目区分时，两组之间没有差异，但有一个例外。一般认知障碍或一般记忆障碍都不能解释这种结果模式。目前的研究结果表明，患者在干扰较高的情况下发现了更多的困难，这对模式分离提出了更高的要求。海马损伤导致的模式分离过程中断为这些结果提供了合理的解释。未来的研究应该探索 mTLE 患者海马亚区完整性与记忆辨别能力之间的因果关系。
