Poster D77, Monday, March 27, 8:00 – 10:00 am, Pacific Concourse
Double dissociation of structure-function relationships between memory and fluid intelligence using magnetic resonance elastography
Hillary Schwarb1, Curtis L. Johnson2, Charles H. Hillman3, Arthur F. Kramer3, Neal J. Cohen1, Aron K. Barbey1; 1Beckman Institute, University of Illinois, 2University of Delaware, 3Northeastern University
Magnetic resonance elastography (MRE) is an emerging technique for probing neural tissue architecture through its mechanical properties by measuring tissue viscoelasticity that reflects the underlying microstructural integrity of the neuronal-glial matrix. Our recent work has suggested that MRE may provide a novel biomarker of tissue integrity that is related to cognitive function; however, only the relationship between hippocampal viscoelasticity and memory performance has been investigated to date. Considering that among healthy young adults, viscoelasticity measures across cortical and subcortical regions are highly correlated, the structure-function specificity of this technique remains an empirical question. In this study (N=52), we investigated the relationship between both hippocampal and prefrontal viscoelasticity and performance on measures of relational memory and fluid intelligence. Despite the observation that cortical and subcortical viscoelasticity is correlated, as is memory and fluid intelligence task performance, we observed a double dissociation suggesting that MRE measures of tissue integrity are indeed functionally separable. Data revealed that hippocampal viscoelasticity significantly correlated with relational memory performance, but not measures of fluid intelligence. Conversely, orbital frontal cortex viscoelasticity significantly correlated with fluid intelligence measures, but not relational memory. These data provide the first evidence that MRE measures of microstructural variability in specific regions of interest may contribute to distinct cognitive processes. This finding enhances our previous observations of the high sensitivity of MRE measures to functional performance, even in the absence of volumetric effects, and further points to the potential for MRE to provide a novel tool for investigating functionally-relevant neural tissue microstructure.
Topic Area: LONG-TERM MEMORY: Episodic