Leibniz-Institute for Neurobiology, Brenneckestrasse 6, 39118 Magdeburg, Germany.
Hum Brain Mapp. 2013 Feb;34(2):407-24. doi: 10.1002/hbm.21435. Epub 2011 Oct 31.
New episodic memory traces represent a record of the ongoing neocortical processing engaged during memory formation (encoding). Thus, during encoding, deep (semantic) processing typically establishes more distinctive and retrievable memory traces than does shallow (perceptual) processing, as assessed by later episodic memory tests. By contrast, the hippocampus appears to play a processing-independent role in encoding, because hippocampal lesions impair encoding regardless of level of processing. Here, we clarified the neural relationship between processing and encoding by examining hippocampal-cortical connectivity during deep and shallow encoding. Participants studied words during functional magnetic resonance imaging and freely recalled these words after distraction. Deep study processing led to better recall than shallow study processing. For both levels of processing, successful encoding elicited activations of bilateral hippocampus and left prefrontal cortex, and increased functional connectivity between left hippocampus and bilateral medial prefrontal, cingulate and extrastriate cortices. Successful encoding during deep processing was additionally associated with increased functional connectivity between left hippocampus and bilateral ventrolateral prefrontal cortex and right temporoparietal junction. In the shallow encoding condition, on the other hand, pronounced functional connectivity increases were observed between the right hippocampus and the frontoparietal attention network activated during shallow study processing. Our results further specify how the hippocampus coordinates recording of ongoing neocortical activity into long-term memory, and begin to provide a neural explanation for the typical advantage of deep over shallow study processing for later episodic memory.
新的情景记忆痕迹代表了记忆形成（编码）过程中持续的新皮质处理的记录。因此，在编码过程中，深度（语义）处理通常比浅层（感知）处理建立更具特色和可检索的记忆痕迹，这可以通过后来的情景记忆测试来评估。相比之下，海马体似乎在编码中起着独立于处理的作用，因为海马体损伤无论处理水平如何都会损害编码。在这里，我们通过检查深度和浅层编码期间海马体-皮质连接，澄清了处理与编码之间的神经关系。参与者在功能磁共振成像期间学习单词，并在分心后自由回忆这些单词。深度学习处理比浅层学习处理导致更好的回忆。对于两种处理水平，成功的编码都会引起双侧海马体和左前额叶皮层的激活，并增加左海马体与双侧内侧前额叶、扣带回和外纹状体皮层之间的功能连接。在深度处理期间成功的编码还与左海马体与双侧腹外侧前额叶皮层和右侧颞顶联合区之间的功能连接增加有关。另一方面，在浅层编码条件下，在浅层学习处理期间激活的右海马体与额顶注意网络之间观察到明显的功能连接增加。我们的结果进一步说明了海马体如何将正在进行的新皮质活动记录到长期记忆中，并开始为深度学习处理相对于浅层学习处理对后来情景记忆的典型优势提供神经解释。
