Department of Epileptology, University Hospital Bonn, Venusberg-Campus 1, 53127 Bonn, Germany.
Department of Epileptology, University Hospital Bonn, Venusberg-Campus 1, 53127 Bonn, Germany; Faculty of Psychology, Swiss Distance University Institute, Ueberlandstr. 12, 3900 Brig, Switzerland.
Neuroimage. 2020 Nov 1;221:117214. doi: 10.1016/j.neuroimage.2020.117214. Epub 2020 Aug 2.
Electrophysiological activity in medial temporal lobe (MTL) structures is pivotal for declarative long-term memory. Single-neuron and microcircuit findings capitalizing on human microwire recordings from the medial temporal lobe are still fragmentary. In particular, it is an open question whether identical or different groups of neurons participate in different memory functions. Here, we investigated category-specific responses in the human MTL based on single-neuron recordings in presurgical epilepsy patients performing an associative long-term memory task. Additionally, auditory beat stimuli were presented during encoding and retrieval to modulate memory performance. We describe the proportion of neurons in amygdala, entorhinal cortex, hippocampus and parahippocampal cortex belonging to different response classes. These entail neurons coding stimulus-familiarity, neurons coding successful item memory, and neurons coding associated source memory, as well as the overlap between these classes. As major results we demonstrate that neurons responding to stimulus familiarity (old/new effect) can be identified in the MTL even when using previously known rather than entirely novel stimulus material (words). We observed a significant overlap between familiarity-related neurons and neurons coding item retrieval (remembered/forgotten effect). The largest fraction of familiarity-related neurons was found in the parahippocampal cortex, and a considerable fraction of all parahippocampal neurons was related to successful item retrieval. Neurons related to successful source retrieval were different from the neurons coding the associated information. Most importantly, there was no overlap between neurons coding item memory and those coding associated source memory strongly suggesting that these functions are facilitated by different sets of neurons.
内侧颞叶 (MTL) 结构中的电生理活动对陈述性长期记忆至关重要。利用人类微丝记录从内侧颞叶获得的单个神经元和微电路发现仍然很零碎。特别是，一个悬而未决的问题是，相同或不同的神经元群体是否参与不同的记忆功能。在这里，我们基于在进行联想长期记忆任务的术前癫痫患者中进行的单神经元记录，研究了人类 MTL 中的类别特异性反应。此外，在编码和检索期间呈现听觉节拍刺激以调节记忆性能。我们描述了属于不同反应类别的神经元在杏仁核、内嗅皮层、海马体和海马旁回中的比例。这些包括编码刺激熟悉度的神经元、编码成功项目记忆的神经元以及编码相关源记忆的神经元，以及这些类之间的重叠。作为主要结果，我们证明即使使用以前已知而不是全新的刺激材料（单词），也可以在 MTL 中识别出对刺激熟悉度做出反应的神经元（旧/新效应）。我们观察到与熟悉度相关的神经元与编码项目检索的神经元之间存在显著重叠（记得/忘记效应）。在海马旁回中发现了与熟悉度相关的神经元的最大比例，并且所有海马旁回神经元的相当大一部分与成功的项目检索有关。与成功源检索相关的神经元与编码相关源记忆的神经元不同。最重要的是，编码项目记忆的神经元与编码相关源记忆的神经元之间没有重叠，这强烈表明这些功能是由不同的神经元集合促进的。
