PDF(Pubmed)
Abstract：
The hippocampus is generally considered to have relatively late involvement in recognition memory, its main electrophysiological signature being between 400 and 800 ms after stimulus onset. However, most electrophysiological studies have analyzed the hippocampus as a single responsive area, selecting only a single-site signal exhibiting the strongest effect in terms of amplitude. These classical approaches may not capture all the dynamics of this structure, hindering the contribution of other hippocampal sources that are not located in the vicinity of the selected site. We combined intracerebral electroencephalogram recordings from epileptic patients with independent component analysis during a recognition memory task involving the recognition of old and new images. We identified two sources with different responses emerging from the hippocampus: a fast one (maximal amplitude at ∼250 ms) that could not be directly identified from raw recordings and a latter one, peaking at ∼400 ms. The former component presented different amplitudes between old and new items in 6 out of 10 patients. The latter component had different delays for each condition, with a faster activation (∼290 ms after stimulus onset) for recognized items. We hypothesize that both sources represent two steps of hippocampal recognition memory, the faster reflecting the input from other structures and the latter the hippocampal internal processing. Recognized images evoking early activations would facilitate neural computation in the hippocampus, accelerating memory retrieval of complementary information. Overall, our results suggest that the hippocampal activity is composed of several sources with an early activation related to recognition memory.
摘要：
海马通常被认为在识别记忆中具有相对较晚的参与，它的主要电生理特征在刺激开始后400和800毫秒之间。然而,大多数电生理研究都将海马体分析为一个单一的反应区，仅选择在振幅方面表现出最强影响的单位点信号。这些经典方法可能无法捕获这种结构的所有动力学，阻碍了其他不位于所选部位附近的海马来源的贡献。在涉及识别新旧图像的识别记忆任务中，我们将癫痫患者的脑内脑电图记录与独立成分分析相结合。Weidentifiedtwosourceswithdifferentresponseemergingfromthehymarcums:afastone(maximumspheritesat〜250ms)thatcouldnotbedirectlyidentifiedfromrawrecordsandalatterone,峰值在400毫秒。在10名患者中的6名患者中，前一部分在新旧项目之间呈现不同的幅度。后一部分对于每个条件都有不同的延迟，对已识别的物品有更快的激活(刺激开始后约290毫秒)。我们假设这两个来源都代表了海马识别记忆的两个步骤，更快地反映来自其他结构的输入，后者反映海马内部处理。唤起早期激活的识别图像将有助于海马体的神经计算，加速互补信息的记忆检索。总的来说,我们的结果表明，海马活动由几个来源组成，这些来源具有与识别记忆相关的早期激活。
