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The neural architecture of the language comprehension network: converging evidence from lesion and connectivity analyses.

Turken AU, Dronkers NF - Front Syst Neurosci (2011)

Bottom Line: 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).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.

View Article: PubMed Central - PubMed

Affiliation: Department of Veterans Affairs Northern California Health Care System, Center for Aphasia and Related Disorders Martinez, CA, USA.

ABSTRACT
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.

No MeSH data available.


Related in: MedlinePlus

Major pathways associated with the left MTG region of interest. Streamline tractography results from two subjects are presented as exemplars. Each row depicts the individual subject's ROI warped to their own native space (left, yellow), followed by sagittal, axial, and coronal perspectives of the fiber bundles involved. The direct and indirect segments of the arcuate fasciculus, the inferior occipito-frontal fasciculus, the middle longitudinal fasciculus, the inferior longitudinal fasciculus, and transcallosal projections, consistent with the tapetum, are shown.
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Figure 3: Major pathways associated with the left MTG region of interest. Streamline tractography results from two subjects are presented as exemplars. Each row depicts the individual subject's ROI warped to their own native space (left, yellow), followed by sagittal, axial, and coronal perspectives of the fiber bundles involved. The direct and indirect segments of the arcuate fasciculus, the inferior occipito-frontal fasciculus, the middle longitudinal fasciculus, the inferior longitudinal fasciculus, and transcallosal projections, consistent with the tapetum, are shown.

Mentions: Region of interests in MNI space were then obtained from the VLSM results for the lesion–symptom analysis in DeArmond et al. (1989) atlas space (Figure 1; Dronkers et al., 2004, Figures 3 and 4) using the same procedure. A smoothing filter (8 mm FWHM Gaussian) was applied to each ROI in order to compensate for registration errors and the residual anatomical variability that remains after the spatial normalization of the healthy subject datasets to MNI space. These ROIs for the MTG, anterior STG/BA22, BA47, BA46, STS/BA39, and the WM subjacent to the STS were saved as binary mask images for the subsequent analyses (Figure 2). It should be noted that the VLSM findings include WM regions as well as the cortical areas listed in Table 3 of Dronkers et al. (2004). Tractography analysis of structural connectivity revealed the WM pathways associated with each ROI, while the functional connectivity analysis was restricted to the cortical gray matter (GM) contained within each ROI.


The neural architecture of the language comprehension network: converging evidence from lesion and connectivity analyses.

Turken AU, Dronkers NF - Front Syst Neurosci (2011)

Major pathways associated with the left MTG region of interest. Streamline tractography results from two subjects are presented as exemplars. Each row depicts the individual subject's ROI warped to their own native space (left, yellow), followed by sagittal, axial, and coronal perspectives of the fiber bundles involved. The direct and indirect segments of the arcuate fasciculus, the inferior occipito-frontal fasciculus, the middle longitudinal fasciculus, the inferior longitudinal fasciculus, and transcallosal projections, consistent with the tapetum, are shown.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3039157&req=5

Figure 3: Major pathways associated with the left MTG region of interest. Streamline tractography results from two subjects are presented as exemplars. Each row depicts the individual subject's ROI warped to their own native space (left, yellow), followed by sagittal, axial, and coronal perspectives of the fiber bundles involved. The direct and indirect segments of the arcuate fasciculus, the inferior occipito-frontal fasciculus, the middle longitudinal fasciculus, the inferior longitudinal fasciculus, and transcallosal projections, consistent with the tapetum, are shown.
Mentions: Region of interests in MNI space were then obtained from the VLSM results for the lesion–symptom analysis in DeArmond et al. (1989) atlas space (Figure 1; Dronkers et al., 2004, Figures 3 and 4) using the same procedure. A smoothing filter (8 mm FWHM Gaussian) was applied to each ROI in order to compensate for registration errors and the residual anatomical variability that remains after the spatial normalization of the healthy subject datasets to MNI space. These ROIs for the MTG, anterior STG/BA22, BA47, BA46, STS/BA39, and the WM subjacent to the STS were saved as binary mask images for the subsequent analyses (Figure 2). It should be noted that the VLSM findings include WM regions as well as the cortical areas listed in Table 3 of Dronkers et al. (2004). Tractography analysis of structural connectivity revealed the WM pathways associated with each ROI, while the functional connectivity analysis was restricted to the cortical gray matter (GM) contained within each ROI.

Bottom Line: 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).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.

View Article: PubMed Central - PubMed

Affiliation: Department of Veterans Affairs Northern California Health Care System, Center for Aphasia and Related Disorders Martinez, CA, USA.

ABSTRACT
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.

No MeSH data available.


Related in: MedlinePlus