In the healthy human brain, evidence for dissociable memory networks along the anterior–posterior axis of the hippocampus suggests that this structure may not function as a unitary entity. Failure to consider these functional divisions may explain diverging results among studies of memory adaptation in disease. Using task-based and resting functional MRI, we show that chronic seizures disrupting the anterior medial temporal lobe (MTL) preserve anterior and posterior hippocampal-cortical dissociations, but alter signaling between these and other key brain regions. During performance of a memory encoding task, we found reduced neural activity in human patients with unilateral temporal lobe epilepsy relative to age-matched healthy controls, but no upregulation of fMRI signal in unaffected hippocampal subregions. Instead, patients showed aberrant resting fMRI connectivity within anterior and posterior hippocampal-cortical networks, which was associated with memory decline, distinguishing memory-intact from memory-impaired patients. Our results highlight a critical role for intact hippocampo-cortical functional communication in memory and provide evidence that chronic injury-induced functional reorganization in the diseased MTL is behavioral inefficient.
Aberrant Functional Connectivity in Dissociable Hippocampal Networks Is Associated with Deficits in Memory
N. Voets,G. Zamboni,M. Stokes,K. Carpenter,R. Stacey,J. Adcock
Published 2014 in Journal of Neuroscience
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- Publication year
2014
- Venue
Journal of Neuroscience
- Publication date
2014-04-02
- Fields of study
Biology, Medicine, Computer Science, Psychology
- Identifiers
- External record
- Source metadata
Semantic Scholar, PubMed
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