Poster C31, Sunday, March 26, 5:00 – 7:00 pm, Pacific Concourse
Age and Modulation of BOLD Response to Task Difficulty: the Protective Effects of Crystallized Knowledge
Zhang Jingting1, Zhuang Song1, Patricia A. Reuter-Lorenz2, Denise C. Park1; 1University of Texas at Dallas, 2University of Michigan
We have previously reported that older adults, compared to young, are less able to modulate the magnitude of the Blood Oxygenation Level Dependent (BOLD) response to task difficulty on a semantic judgment task (Kennedy et al., 2015). Here we investigated whether neural enrichment factors, such as crystallized knowledge, might be protective of modulatory capacity in the context of healthy aging. We studied 463 participants (20-89 years) who judged ambiguous (Hard) and unambiguous (Easy) words for animacy in an fMRI block design. Age and crystallized ability were entered as separate steps in hierarchical regression models to assess whether crystallized knowledge accounted for variance in modulation beyond age. We found that older adults had decreased modulation of BOLD response to difficulty in medial frontal and bilateral inferior frontal gyri (IFG), but after controlling for age, better crystallized knowledge predicted more modulation in these frontal regions. Moreover, a second analysis showed that higher modulation in these frontal regions predicted better performance in reasoning and executive function across the adult lifespan. Additionally, higher modulation in medial frontal and right IFG predicted better working memory in both the middle-aged (45-64 years) and younger-old (65-80 years) groups but not the very old group (80-89 years). These effects remained even after we corrected crystallized ability for fluid intelligence. Our findings suggested that high modulatory capability is impaired with age and is important for cognitive functions and that crystallized knowledge appears to be a type of cognitive reserve that protects modulation of brain activity in core control regions.
Topic Area: EXECUTIVE PROCESSES: Development & aging