Sisakhti Minoo, Sachdev Perminder S, Batouli Seyed Amir Hossein
Institute for Cognitive Sciences Studies, Tehran, Iran.
Neuroimaging and Analysis Group, Research Center for Molecular and Cellular Imaging, Tehran University of Medical Sciences, Tehran, Iran.
Front Hum Neurosci. 2021 Oct 13;15:700146. doi: 10.3389/fnhum.2021.700146. eCollection 2021.
One of the less well-understood aspects of memory function is the mechanism by which the brain responds to an increasing load of memory, either during encoding or retrieval. Identifying the brain structures which manage this increasing cognitive demand would enhance our knowledge of human memory. Despite numerous studies about the effect of cognitive loads on working memory processes, whether these can be applied to long-term memory processes is unclear. We asked 32 healthy young volunteers to memorize all possible details of 24 images over a 12-day period ending 2 days before the fMRI scan. The images were of 12 categories relevant to daily events, with each category including a high and a low load image. Behavioral assessments on a separate group of participants (#22) provided the average loads of the images. The participants had to retrieve these previously memorized images during the fMRI scan in 15 s, with their eyes closed. We observed seven brain structures showing the highest activation with increasing load of the retrieved images, viz. parahippocampus, cerebellum, superior lateral occipital, fusiform and lingual gyri, precuneus, and posterior cingulate gyrus. Some structures showed reduced activation when retrieving higher load images, such as the anterior cingulate, insula, and supramarginal and postcentral gyri. The findings of this study revealed that the mechanism by which a difficult-to-retrieve memory is handled is mainly by elevating the activation of the responsible brain areas and not by getting other brain regions involved, which is a help to better understand the LTM retrieval process in the human brain.
记忆功能中一个尚未被充分理解的方面是大脑在编码或检索过程中对不断增加的记忆负荷做出反应的机制。确定管理这种不断增加的认知需求的脑结构将增进我们对人类记忆的了解。尽管有大量关于认知负荷对工作记忆过程影响的研究，但这些研究是否适用于长期记忆过程尚不清楚。我们让32名健康的年轻志愿者在功能磁共振成像扫描前2天结束的12天内记住24张图像的所有可能细节。这些图像属于与日常事件相关的12个类别，每个类别包括一张高负荷图像和一张低负荷图像。对另一组参与者（22名）的行为评估提供了这些图像的平均负荷。参与者必须在功能磁共振成像扫描期间闭上眼睛，在15秒内检索这些先前记忆的图像。我们观察到七个脑结构随着检索图像负荷的增加而显示出最高的激活，即海马旁回、小脑、枕外侧上回、梭状回和舌回、楔前叶和后扣带回。一些结构在检索高负荷图像时显示出激活减少，如前扣带回、岛叶、缘上回和中央后回。这项研究的结果表明，处理难以检索的记忆的机制主要是通过提高负责脑区的激活，而不是让其他脑区参与，这有助于更好地理解人类大脑中的长期记忆检索过程。
