title: Influence of functional connectivity and structural MRI measures on episodic memory.
abstract: Age-related memory decline is the consequence of multiple biological factors that lead to brain structural and functional change, including gray matter atrophy, white matter injury, and loss of functional coordination between regions. However, the independent roles that each of these brain changes play in mediating memory decline is not clear. Therefore, we used magnetic resonance imaging (MRI) to measure gray matter (GM) volume, white matter hyperintensity (WMH) volumes, and blood oxygen level-dependent (BOLD) functional magnetic resonance imaging-based functional connectivity among default mode network nodes in 76 cognitive normal older adults. We found that GM, WMH, and connectivity between left inferior parietal and medial prefrontal cortex (MPF_LIP) were independently associated with episodic memory performance. Within the group with GM volumes below the median, greater MPF_LIP connectivity was associated with better memory performance, whereas this association was not present for individuals with GM volume above the median. These findings confirm the heterogeneous nature of brain-behavior relationships in cognitive aging. In addition, the relationship between resting state functional connectivity and memory performance, particularly amongst those individuals with more brain atrophy, strongly suggests compensation against the effects of neuronal injury.
authors.affiliation: Imaging of Dementia and Aging (IDeA) Laboratory, Department of Neurology, University of California, Davis, Davis, CA 95618, USA. jing.he@ucdmc.ucdavis.edu
authors.forename: Jing
authors.initials: J
authors.lastname: He
authors.forename: Owen
authors.initials: O
authors.lastname: Carmichael
authors.forename: Evan
authors.initials: E
authors.lastname: Fletcher
authors.forename: Baljeet
authors.initials: B
authors.lastname: Singh
authors.forename: Ana-Maria
authors.initials: AM
authors.lastname: Iosif
authors.forename: Oliver
authors.initials: O
authors.lastname: Martinez
authors.forename: Bruce
authors.initials: B
authors.lastname: Reed
authors.forename: Andy
authors.initials: A
authors.lastname: Yonelinas
authors.forename: Charles
authors.initials: C
authors.lastname: Decarli
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D001284:Atrophy; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D061212:Memory, Episodic; D008875:Middle Aged