Campo Pablo, Maestú Fernando, Ortiz Tomás, Capilla Almudena, Fernández Santiago, Fernández Alberto
Centro de Magnetoencefalografía Dr. Pérez-Modrego, Universidad Complutense de Madrid, Spain.
Neuroimage. 2005 Mar;25(1):34-42. doi: 10.1016/j.neuroimage.2004.07.074. Epub 2005 Jan 20.
Several neuroimaging studies have consistently demonstrated the critical involvement of prefrontal cortices and medial temporal lobes during long-term encoding. While the contribution of prefrontal lobes to working memory is well established, the role of the MTL structures remains controversial. To address this issue, we registered the neuromagnetic brain patterns of eight adult volunteers while they performed two working memory tasks (verbal and spatial) using magnetoencephalography (MEG). MEG recordings can provide real-time measures of brain activity, thus allowing detailed tracking of the time-course of brain activation during the encoding phase. We detected sustained and material-specific activity on the MTLs during the encoding phase of a working memory task, based on verbal and spatial information. Two peaks of activation were noted in the left MTL during word encoding in two non-consecutive time periods (500-600 ms and 700-800 ms after stimulus onset). Right MTL laterality was found for encoding locations when we collapsed activity sources in a wider time period (400-800 ms). In addition, we provided the spatiotemporal profiles of what seems to be two different brain circuits specific for each type of material. Finally, following an emerging conceptualization of working memory, we hypothesized that encoding processes mediated by the MTL to long-term memory would also apply to working memory.
多项神经影像学研究一致表明，前额叶皮质和内侧颞叶在长期编码过程中起着关键作用。虽然前额叶对工作记忆的贡献已得到充分证实，但内侧颞叶结构的作用仍存在争议。为了解决这个问题，我们利用脑磁图（MEG）记录了8名成年志愿者在执行两项工作记忆任务（言语和空间任务）时的脑磁模式。MEG记录可以提供大脑活动的实时测量，从而能够详细追踪编码阶段大脑激活的时间进程。基于言语和空间信息，我们在工作记忆任务的编码阶段检测到内侧颞叶存在持续的、与材料相关的活动。在单词编码过程中，左侧内侧颞叶在两个不连续的时间段（刺激开始后500 - 600毫秒和700 - 800毫秒）出现了两个激活峰值。当我们在更宽的时间段（400 - 800毫秒）汇总活动源时，发现右侧内侧颞叶在编码位置上具有偏向性。此外，我们提供了似乎针对每种材料的两种不同脑回路的时空分布图。最后，根据工作记忆的一种新出现的概念，我们假设由内侧颞叶介导的从工作记忆到长期记忆的编码过程也适用于工作记忆。
