title: The relationship between level of processing and hippocampal-cortical functional connectivity during episodic memory formation in humans.
abstract: 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.
authors: Leibniz-Institute for Neurobiology, Brenneckestrasse 6, 39118 Magdeburg, Germany. bjoern.schott@med.ovgu.de
authors: Björn H
authors: BH
authors: Schott
authors: Torsten
authors: T
authors: Wüstenberg
authors: Maria
authors: M
authors: Wimber
authors: Daniela B
authors: DB
authors: Fenker
authors: Kathrin C
authors: KC
authors: Zierhut
authors: Constanze I
authors: CI
authors: Seidenbecher
authors: Hans-Jochen
authors: HJ
authors: Heinze
authors: Henrik
authors: H
authors: Walter
authors: Emrah
authors: E
authors: Düzel
authors: Alan
authors: A
authors: Richardson-Klavehn
mesh_terms: D000293:Adolescent; D000328:Adult; D000465:Algorithms; D000704:Analysis of Variance; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000502:physiology*; D003627:Data Interpretation, Statistical; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006624:Hippocampus / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D061212:Memory, Episodic; D011939:Mental Recall / Q000502:physiology; D015233:Models, Statistical; D009434:Neural Pathways / Q000502:physiology*; D010775:Photic Stimulation; D011597:Psychomotor Performance / Q000502:physiology; D011603:Psychophysiology; D011930:Reaction Time / Q000502:physiology; D011932:Reading; D055815:Young Adult