Poster F89, Tuesday, March 27, 8:00-10:00 am, Exhibit Hall C
Aging in the sensorimotor system: Lower GABA levels are associated with decreased network segregation and impaired behavior
Kaitlin Cassady1, Holly Gagnon1, Poortata Lalwani1, Molly Simmonite1, Bradley Foerster2, Denise Park3, Myria Petrou2, Rachael D. Seidler1,4,5, Stephan Taylor1,6, Daniel H. Weissman1, Thad A. Polk1; 1Department of Psychology, University of Michigan, Ann Arbor, MI, USA, 2Department of Radiology, University of Michigan, Ann Arbor, MI, USA, 3Research of the Center for Vital Longevity, University of Texas at Dallas, Dallas, TX, USA, 4School of Kinesiology, University of Michigan, Ann Arbor, MI, USA, 5Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI, USA, 6Department of Psychiatry, University of Michigan, Ann Arbor, MI, USA
Normal aging is typically associated with declines in sensorimotor function. Previous studies have linked some age-related behavioral impairments to reductions in network segregation: Compared to young adults, older adults typically exhibit weaker connectivity between brain regions within the same functional network but stronger connectivity between regions belonging to different networks. Based on animal work, we hypothesized that reduced network segregation is linked to age-related reductions in the brain’s major inhibitory transmitter, gamma aminobutyric acid (GABA). We performed graph theoretical analysis of resting state functional MRI data to measure network segregation in 16 young adults (ages 18-29) and 16 older adults (ages 65-79). We also used magnetic resonance spectroscopy to measure GABA levels in the sensorimotor cortex and collected a battery of behavioral measures in the same participants. We found that brain networks were less segregated in older compared to young adults and that sensorimotor GABA levels were also reduced. Furthermore, lower GABA levels predicted worse cognitive and sensorimotor performance, and this relationship was mediated by network segregation. These findings suggest a mechanistic link from age-related declines in GABA levels to reductions in network segregation and behavioral impairments in the sensorimotor system.
Topic Area: PERCEPTION & ACTION: Development & aging