Race Elizabeth, Palombo Daniela J, Cadden Margaret, Burke Keely, Verfaellie Mieke
Memory Disorders Research Center, VA Boston Healthcare System and Boston University School of Medicine, 150S. Huntington Avenue (151-A), Boston, MA 02130, USA.
Memory Disorders Research Center, VA Boston Healthcare System and Boston University School of Medicine, 150S. Huntington Avenue (151-A), Boston, MA 02130, USA.
Neuropsychologia. 2015 Apr;70:272-80. doi: 10.1016/j.neuropsychologia.2015.02.004. Epub 2015 Mar 6.
Short-term memory (STM) and long-term memory (LTM) have traditionally been considered cognitively distinct. However, it is known that STM can improve when to-be-remembered information appears in contexts that make contact with prior knowledge, suggesting a more interactive relationship between STM and LTM. The current study investigated whether the ability to leverage LTM in support of STM critically depends on the integrity of the hippocampus. Specifically, we investigated whether the hippocampus differentially supports between-domain versus within-domain STM-LTM integration given prior evidence that the representational domain of the elements being integrated in memory is a critical determinant of whether memory performance depends on the hippocampus. In Experiment 1, we investigated hippocampal contributions to within-domain STM-LTM integration by testing whether immediate verbal recall of words improves in MTL amnesic patients when words are presented in familiar verbal contexts (meaningful sentences) compared to unfamiliar verbal contexts (random word lists). Patients demonstrated a robust sentence superiority effect, whereby verbal STM performance improved in familiar compared to unfamiliar verbal contexts, and the magnitude of this effect did not differ from that in controls. In Experiment 2, we investigated hippocampal contributions to between-domain STM-LTM integration by testing whether immediate verbal recall of digits improves in MTL amnesic patients when digits are presented in a familiar visuospatial context (a typical keypad layout) compared to an unfamiliar visuospatial context (a random keypad layout). Immediate verbal recall improved in both patients and controls when digits were presented in the familiar compared to the unfamiliar keypad array, indicating a preserved ability to integrate activated verbal information with stored visuospatial knowledge. Together, these results demonstrate that immediate verbal recall in amnesia can benefit from two distinct types of semantic support, verbal and visuospatial, and that the hippocampus is not critical for leveraging stored semantic knowledge to improve memory performance.
传统上，短期记忆（STM）和长期记忆（LTM）在认知上被认为是不同的。然而，众所周知，当要记忆的信息出现在与先前知识相关的情境中时，短期记忆可以得到改善，这表明短期记忆和长期记忆之间存在更具交互性的关系。当前的研究调查了利用长期记忆来支持短期记忆的能力是否关键取决于海马体的完整性。具体而言，鉴于先前的证据表明，记忆中被整合元素的表征领域是记忆表现是否依赖于海马体的关键决定因素，我们研究了海马体在跨领域与领域内短期记忆 - 长期记忆整合方面是否有不同的支持作用。在实验1中，我们通过测试与不熟悉的语言情境（随机单词列表）相比，当单词出现在熟悉的语言情境（有意义的句子）中时，内侧颞叶失忆症患者对单词的即时言语回忆是否会改善，来研究海马体对领域内短期记忆 - 长期记忆整合的贡献。患者表现出强烈的句子优势效应，即与不熟悉的语言情境相比，在熟悉的语言情境中言语短期记忆表现有所改善，并且这种效应的大小与对照组没有差异。在实验2中，我们通过测试与不熟悉的视觉空间情境（随机键盘布局）相比，当数字出现在熟悉的视觉空间情境（典型的键盘布局）中时，内侧颞叶失忆症患者对数字的即时言语回忆是否会改善，来研究海马体对跨领域短期记忆 - 长期记忆整合的贡献。当数字呈现在熟悉的键盘阵列而非不熟悉的键盘阵列中时，患者和对照组的即时言语回忆都有所改善，这表明将激活的言语信息与存储的视觉空间知识进行整合的能力得以保留。总之，这些结果表明，失忆症患者的即时言语回忆可以从两种不同类型的语义支持（言语和视觉空间）中受益，并且海马体对于利用存储的语义知识来改善记忆表现并非至关重要。
