TY - JOUR
T1 - Temporal lobe white matter asymmetry and language laterality in epilepsy patients
AU - Ellmore, Timothy M.
AU - Beauchamp, Michael S.
AU - Breier, Joshua I.
AU - Slater, Jeremy D.
AU - Kalamangalam, Giridhar P.
AU - O'Neill, Thomas J.
AU - Disano, Michael A.
AU - Tandon, Nitin
N1 - Funding Information:
This project was supported by the Epilepsy Foundation through the generous support of the Gertrude A. Sergievsky Research Endowment (2008 Behavioral Sciences Post-Doctoral Fellowship to T.M.E.), the Vivian L. Smith Foundation for Neurological Research, and a pilot project award (P.I.–N.T.) from the Center for Clinical and Translational Sciences, which is funded by Grant Number UL1RR024148 from the National Center for Research Resources of the National Institutes of Health. Partial funding for the purchase of the Philips 3T scanner used to collect the imaging data was provided by NIH S10 RR19186.
PY - 2010/2/1
Y1 - 2010/2/1
N2 - Recent studies using diffusion tensor imaging (DTI) have advanced our knowledge of the organization of white matter subserving language function. It remains unclear, however, how DTI may be used to predict accurately a key feature of language organization: its asymmetric representation in one cerebral hemisphere. In this study of epilepsy patients with unambiguous lateralization on Wada testing (19 left and 4 right lateralized subjects; no bilateral subjects), the predictive value of DTI for classifying the dominant hemisphere for language was assessed relative to the existing standard-the intra-carotid Amytal (Wada) procedure. Our specific hypothesis is that language laterality in both unilateral left- and right-hemisphere language dominant subjects may be predicted by hemispheric asymmetry in the relative density of three white matter pathways terminating in the temporal lobe implicated in different aspects of language function: the arcuate (AF), uncinate (UF), and inferior longitudinal fasciculi (ILF). Laterality indices computed from asymmetry of high anisotropy AF pathways, but not the other pathways, classified the majority (19 of 23) of patients using the Wada results as the standard. A logistic regression model incorporating information from DTI of the AF, fMRI activity in Broca's area, and handedness was able to classify 22 of 23 (95.6%) patients correctly according to their Wada score. We conclude that evaluation of highly anisotropic components of the AF alone has significant predictive power for determining language laterality, and that this markedly asymmetric distribution in the dominant hemisphere may reflect enhanced connectivity between frontal and temporal sites to support fluent language processes. Given the small sample reported in this preliminary study, future research should assess this method on a larger group of patients, including subjects with bi-hemispheric dominance.
AB - Recent studies using diffusion tensor imaging (DTI) have advanced our knowledge of the organization of white matter subserving language function. It remains unclear, however, how DTI may be used to predict accurately a key feature of language organization: its asymmetric representation in one cerebral hemisphere. In this study of epilepsy patients with unambiguous lateralization on Wada testing (19 left and 4 right lateralized subjects; no bilateral subjects), the predictive value of DTI for classifying the dominant hemisphere for language was assessed relative to the existing standard-the intra-carotid Amytal (Wada) procedure. Our specific hypothesis is that language laterality in both unilateral left- and right-hemisphere language dominant subjects may be predicted by hemispheric asymmetry in the relative density of three white matter pathways terminating in the temporal lobe implicated in different aspects of language function: the arcuate (AF), uncinate (UF), and inferior longitudinal fasciculi (ILF). Laterality indices computed from asymmetry of high anisotropy AF pathways, but not the other pathways, classified the majority (19 of 23) of patients using the Wada results as the standard. A logistic regression model incorporating information from DTI of the AF, fMRI activity in Broca's area, and handedness was able to classify 22 of 23 (95.6%) patients correctly according to their Wada score. We conclude that evaluation of highly anisotropic components of the AF alone has significant predictive power for determining language laterality, and that this markedly asymmetric distribution in the dominant hemisphere may reflect enhanced connectivity between frontal and temporal sites to support fluent language processes. Given the small sample reported in this preliminary study, future research should assess this method on a larger group of patients, including subjects with bi-hemispheric dominance.
KW - Arcuate fasciculus
KW - Broca's area
KW - Diffusion tensor imaging
KW - Functional magnetic resonance imaging
KW - Handedness
KW - Inferior longitudinal fasciculus
KW - Inferior occipitofrontal fasciculus
KW - Language
KW - Laterality
KW - Uncinate fasciculus
KW - Wada (sodium Amytal) test
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U2 - 10.1016/j.neuroimage.2009.10.055
DO - 10.1016/j.neuroimage.2009.10.055
M3 - Article
C2 - 19874899
AN - SCOPUS:71849115147
SN - 1053-8119
VL - 49
SP - 2033
EP - 2044
JO - NeuroImage
JF - NeuroImage
IS - 3
ER -