Brain Advance Access originally published online on October 24, 2008
Brain 2008 131(12):3209-3221; doi:10.1093/brain/awn247
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Structural dissociation of attentional control and memory in adults with and without mild traumatic brain injury
1Sackler Institute for Developmental Psychobiology, Weill Cornell Medical College, New York, NY, 2Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, 3Brain Trauma Foundation, 4Department of Neurological Surgery, 5Department of Radiology, Weill Cornell Medical College, New York, NY, 6Department of Neurological Surgery, University of California, San Francisco, CA, USA, 7Biological Science Department, Sungkyunkwan University, Suwon, South Korea and 8Department of Psychology and Human Development, Vanderbilt University, Nasville, TN, USA
Correspondence to: Bruce D. McCandliss, 1300 York Ave, Box 140, New York, NY 10021, USA E-mail: bdm2001{at}med.cornell.edu
Memory and attentional control impairments are the two most common forms of dysfunction following mild traumatic brain injury (TBI) and lead to significant morbidity in patients, yet these functions are thought to be supported by different brain networks. This 3 T magnetic resonance diffusion tensor imaging (DTI) study investigates whether microstructural integrity of white matter, as measured by fractional anisotropy (FA) within a small set of individually localized regions of interest (ROIs), is associated with these cognitive domains in normal adults and adults with mild TBI. Results in a sample of 23 normal controls reveal a significant correlation between attentional control and FA within a ROI in the left hemisphere anterior corona radiata. Furthermore, the controls demonstrate a correlation between memory performance and FA in a ROI placed in the uncinate fasciculus. Next, to examine whether these relationships are found in the pathological ranges of attention, memory and microstructural white matter integrity associated with mild TBI, these analyses were applied to a group of 43 mild TBI patients. Results, which generally demonstrated a wider range of attention, memory and FA scores, replicated the correlation between attentional control and FA in left hemisphere anterior corona radiata, as well as the correlation between memory performance and FA in the uncinate fasciculus. These two sets of brain-behaviour relationships were highly specific, as shown by a lack of correlation between attention and uncinate fasciculus FA and the lack of correlation between memory performance and anterior corona radiata FA. Furthermore, a ‘correlational double dissociation’ was demonstrated to exist between two distinct frontal structures independently associated with attention and memory, respectively, via a series of multiple regression analyses in both normal controls and adults with mild TBI. The results of the multiple regression analyses provide direct evidence that tract-specific variation in microstructural white matter integrity among normal controls and among mild TBI patients can account for much of the variation in performance in specific cognitive domains. More generally, such findings suggest that diffusion anisotropy measurement can be used as a quantitative biomarker for neurocognitive function and dysfunction.
Key Words: diffusion tensor imaging; traumatic brain injury; executive function; executive attention; memory
Abbreviations: ACR, anterior corona radiata; ANT, attention network task; CB, cingulum bundle; CVLT-II, California verbal learning test, second edition; DTI, diffusion tensor imaging; FA, fractional anisotropy; ICC, intraclass correlation coefficient; ILF, inferior longitudinal fasciculus; LDFR, long delay free recall; ROI, region of interest; SDFR, short delay free recall; SLF, superior longitudinal fasciculus; TBI, traumatic brain injury; UF, uncinate fasciculus
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Received March 12, 2008. Revised September 4, 2008. Accepted September 8, 2008.
*These authors contributed equally to this work.
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