Department of Neurosciences, University of California San Diego, San Diego, California, United States of America.
Department of Neurosciences, University of California San Diego, San Diego, California, United States of America ; Department of Radiology, University of California San Diego, San Diego, California, United States of America.
PLoS One. 2014 Feb 19;9(2):e89037. doi: 10.1371/journal.pone.0089037. eCollection 2014.
Functional imaging studies of episodic memory retrieval consistently report task-evoked and memory-related activity in the medial temporal lobe, default network and parietal lobe subregions. Associated components of memory retrieval, such as attention-shifts, search, retrieval success, and post-retrieval processing also influence regional activity, but these influences remain ill-defined. To better understand how top-down control affects the neural bases of memory retrieval, we examined how regional activity responses were modulated by task goals during recall success or failure. Specifically, activity was examined during memory suppression, recall, and elaborative recall of paired-associates. Parietal lobe was subdivided into dorsal (BA 7), posterior ventral (BA 39), and anterior ventral (BA 40) regions, which were investigated separately to examine hypothesized distinctions in sub-regional functional responses related to differential attention-to-memory and memory strength. Top-down suppression of recall abolished memory strength effects in BA 39, which showed a task-negative response, and BA 40, which showed a task-positive response. The task-negative response in default network showed greater negatively-deflected signal for forgotten pairs when task goals required recall. Hippocampal activity was task-positive and was influenced by memory strength only when task goals required recall. As in previous studies, we show a memory strength effect in parietal lobe and hippocampus, but we show that this effect is top-down controlled and sensitive to whether the subject is trying to suppress or retrieve a memory. These regions are all implicated in memory recall, but their individual activity patterns show distinct memory-strength-related responses when task goals are varied. In parietal lobe, default network, and hippocampus, top-down control can override the commonly identified effects of memory strength.
情景记忆检索的功能成像研究一致报告了内侧颞叶、默认网络和顶叶亚区的任务诱发和记忆相关活动。记忆检索的相关成分,如注意力转移、搜索、检索成功和检索后处理,也会影响区域活动,但这些影响仍未得到明确界定。为了更好地理解自上而下的控制如何影响记忆检索的神经基础,我们研究了在回忆成功或失败时,任务目标如何调节区域活动反应。具体来说,在记忆抑制、回忆和联想回忆过程中,我们检查了顶叶的活动。顶叶被细分为背侧(BA7)、后腹侧(BA39)和前腹侧(BA40)区域,分别进行研究,以检查与注意力到记忆和记忆强度的差异相关的亚区域功能反应的假设差异。回忆的自上而下抑制消除了 BA39 和 BA40 中记忆强度的影响,BA39 表现出任务负反应,BA40 表现出任务正反应。默认网络中的任务负反应在需要回忆任务目标时,对被遗忘的对呈现出更大的负信号。海马体活动是任务正相关的,只有当任务目标要求回忆时,才会受到记忆强度的影响。与之前的研究一样,我们在顶叶和海马体中显示了记忆强度效应,但我们表明,这种效应是自上而下控制的,并且对主体是试图抑制还是检索记忆敏感。这些区域都与记忆回忆有关,但当任务目标发生变化时,它们的个体活动模式显示出与记忆强度相关的不同反应。在顶叶、默认网络和海马体中,自上而下的控制可以覆盖记忆强度的常见影响。