Buckner R L, Koutstaal W, Schacter D L, Wagner A D, Rosen B R
Department of Psychology, Washington University, St. Louis, Missouri 63130, USA.
Neuroimage. 1998 Apr;7(3):151-62. doi: 10.1006/nimg.1998.0327.
A number of recent functional imaging studies have identified brain areas activated during tasks involving episodic memory retrieval. The identification of such areas provides a foundation for targeted hypotheses regarding the more specific contributions that these areas make to episodic retrieval. As a beginning effort toward such an endeavor, whole-brain functional magnetic resonance imaging (fMRI) was used to examine 14 subjects during episodic word recognition in a block-designed fMRI experiment. Study conditions were manipulated by presenting either shallow or deep encoding tasks. This manipulation yielded two recognition conditions that differed with regard to retrieval effort and retrieval success: shallow encoding yielded low levels of recognition success with high levels of retrieval effort, and deep encoding yielded high levels of recognition success with low levels of effort. Many brain areas were activated in common by these two recognition conditions compared to a low-level fixation condition, including left and right prefrontal regions often detected during PET episodic retrieval paradigms (e.g., R. L. Buckner et al., 1996, J. Neurosci. 16, 6219-6235) thereby generalizing these findings to fMRI. Characterization of the activated regions in relation to the separate recognition conditions showed (1) bilateral anterior insular regions and a left dorsal prefrontal region were more active after shallow encoding, when retrieval demanded greatest effort, and (2) right anterior prefrontal cortex, which has been implicated in episodic retrieval, was most active during successful retrieval after deep encoding. We discuss these findings in relation to component processes involved in episodic retrieval and in the context of a companion study using event-related fMRI.
最近的一些功能成像研究已经确定了在涉及情景记忆检索的任务中被激活的脑区。这些脑区的确定为关于这些区域对情景检索做出更具体贡献的针对性假设提供了基础。作为朝着这一目标迈出的第一步，在一项采用组块设计的功能磁共振成像（fMRI）实验中，使用全脑功能磁共振成像来检查14名受试者在情景单词识别过程中的情况。通过呈现浅编码任务或深编码任务来操控研究条件。这种操控产生了两种在检索努力程度和检索成功率方面存在差异的识别条件：浅编码导致低水平的识别成功率和高水平的检索努力程度，而深编码则导致高水平的识别成功率和低水平的努力程度。与低水平注视条件相比，这两种识别条件共同激活了许多脑区，包括在PET情景检索范式中经常检测到的左右前额叶区域（例如，R. L. 巴克纳等人，1996年，《神经科学杂志》16卷，6219 - 6235页），从而将这些发现推广到了功能磁共振成像研究中。对与不同识别条件相关的激活区域的特征分析表明：（1）双侧前岛叶区域和左侧背侧前额叶区域在浅编码后更为活跃，此时检索需要最大的努力；（2）与情景检索有关的右侧前额叶皮层在深编码后的成功检索过程中最为活跃。我们将结合情景检索所涉及的组成过程以及在一项使用事件相关功能磁共振成像的配套研究背景下讨论这些发现。
