While traditional models of language comprehension have focused on the left posterior temporal cortex as the neurological basis for language comprehension, lesion and functional imaging studies indicate the involvement of an extensive network of cortical regions. However, the full extent of this network and the white matter pathways that contribute to it remain to be characterized. In an earlier voxel-based lesion-symptom mapping analysis of data from aphasic patients (Dronkers et al., 2004), several brain regions in the left hemisphere were found to be critical for language comprehension: the left posterior middle temporal gyrus, the anterior part of Brodmann’s area 22 in the superior temporal gyrus (anterior STG/BA22), the posterior superior temporal sulcus (STS) extending into Brodmann’s area 39 (STS/BA39), the orbital part of the inferior frontal gyrus (BA47), and the middle frontal gyrus (BA46). Here, we investigated the white matter pathways associated with these regions using diffusion tensor imaging from healthy subjects. We also used resting-state functional magnetic resonance imaging data to assess the functional connectivity profiles of these regions. Fiber tractography and functional connectivity analyses indicated that the left MTG, anterior STG/BA22, STS/BA39, and BA47 are part of a richly interconnected network that extends to additional frontal, parietal, and temporal regions in the two hemispheres. The inferior occipito-frontal fasciculus, the arcuate fasciculus, and the middle and inferior longitudinal fasciculi, as well as transcallosal projections via the tapetum were found to be the most prominent white matter pathways bridging the regions important for language comprehension. The left MTG showed a particularly extensive structural and functional connectivity pattern which is consistent with the severity of the impairments associated with MTG lesions and which suggests a central role for this region in language comprehension.
Keywords: aphasia, language comprehension, language network, structural connectivity, fiber tracts, resting-state functional connectivity, disconnection, middle temporal gyrus
Citation: Turken AU and Dronkers NF (2011) The neural architecture of the language comprehension network: converging evidence from lesion and connectivity analyses. Front. Syst. Neurosci. 5:1. doi: 10.3389/fnsys.2011.00001
Received: 03 November 2010;
Accepted: 03 January 2011;
Published online: 10 February 2011.
Edited by:Barry Horwitz, National Institutes of Health, USA
Reviewed by:Jeffrey R. Binder, Medical College of Wisconsin, USA
Copyright: © 2011 Turken and Dronkers. This is an open-access article subject to an exclusive license agreement between the authors and Frontiers Media SA, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are credited.
*Correspondence: And U. Turken, Veterans Affairs Northern California Health Care System, Research Service R4 151/MTZ, 150 Muir Road, Martinez, CA 94553, USA. e-mail: firstname.lastname@example.org; Nina F. Dronkers, Veterans Affairs Northern California Health Care System, Center for Aphasia and Related Disorders (126R), 150 Muir Road, Martinez, CA 94553, USA. e-mail: email@example.com