title: Longitudinal Evidence for Dissociation of Anterior and Posterior MTL Resting-State Connectivity in Aging: Links to Perfusion and Memory.
abstract: Neuroimaging studies of spontaneous signal fluctuations as measured by resting-state functional magnetic resonance imaging have revealed age-related alterations in the functional architecture of brain networks. One such network is located in the medial temporal lobe (MTL), showing structural and functional variations along the anterior-posterior axis. Past cross-sectional studies of MTL functional connectivity (FC) have yielded discrepant findings, likely reflecting the fact that specific MTL subregions are differentially affected in aging. Here, using longitudinal resting-state data from 198 participants, we investigated 5-year changes in FC of the anterior and posterior MTL. We found an opposite pattern, such that the degree of FC within the anterior MTL declined after age 60, whereas elevated FC within the posterior MTL was observed along with attenuated posterior MTL-cortical connectivity. A significant negative change-change relation was observed between episodic-memory decline and elevated FC in the posterior MTL. Additional analyses revealed age-related cerebral blood flow (CBF) increases in posterior MTL at the follow-up session, along with a positive relation of elevated FC and CBF, suggesting that elevated FC is a metabolically demanding alteration. Collectively, our findings indicate that elevated FC in posterior MTL along with increased local perfusion is a sign of brain aging that underlie episodic-memory decline.
authors: Umeå Center for Functional Brain Imaging, S-90187, Umeå, Sweden.|Department of Integrative Medical Biology, Physiology Section, Umeå University, S-901 87 Umeå, Sweden.|Aging Research Center, Karolinska Institutet and Stockholm University, SE-113 30, Stockholm, Sweden.
authors: Alireza
authors: A
authors: Salami
authors: Umeå Center for Functional Brain Imaging, S-90187, Umeå, Sweden.|Department of Radiation Sciences, Radiation Physics, Umeå University, S-901 87 Umeå, Sweden.
authors: Anders
authors: A
authors: Wåhlin
authors: Umeå Center for Functional Brain Imaging, S-90187, Umeå, Sweden.|Aging Research Center, Karolinska Institutet and Stockholm University, SE-113 30, Stockholm, Sweden.
authors: Neda
authors: N
authors: Kaboodvand
authors: Umeå Center for Functional Brain Imaging, S-90187, Umeå, Sweden.|Department of Integrative Medical Biology, Physiology Section, Umeå University, S-901 87 Umeå, Sweden.
authors: Anders
authors: A
authors: Lundquist
authors: Umeå Center for Functional Brain Imaging, S-90187, Umeå, Sweden.|Department of Integrative Medical Biology, Physiology Section, Umeå University, S-901 87 Umeå, Sweden.|Department of Radiation Sciences, Diagnostic Radiology, Umeå University, S-901 87 Umeå, Sweden.
authors: Lars
authors: L
authors: Nyberg
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology* / Q000523:psychology*; D001931:Brain Mapping; D002560:Cerebrovascular Circulation / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D008297:Male; D008569:Memory Disorders / Q000000981:diagnostic imaging / Q000503:physiopathology; D061212:Memory, Episodic; D008875:Middle Aged; D009434:Neural Pathways / Q000098:blood supply / Q000000981:diagnostic imaging / Q000502:physiology; D009929:Organ Size; D011446:Prospective Studies; D012146:Rest; D013702:Temporal Lobe / Q000098:blood supply / Q000000981:diagnostic imaging / Q000502:physiology*
keywords: episodic memory, functional connectivity, longitudinal, anterior and posterior MTL, perfusion