title: White matter structural connectivity underlying semantic processing: evidence from brain damaged patients.
abstract: Widely distributed brain regions in temporal, parietal and frontal cortex have been found to be involved in semantic processing, but the anatomical connections supporting the semantic system are not well understood. In a group of 76 right-handed brain-damaged patients, we tested the relationship between the integrity of major white matter tracts and the presence of semantic deficits. The integrity of white matter tracts was measured by percentage of lesion voxels obtained in structural imaging and mean fractional anisotropy values obtained in diffusion tensor imaging. Semantic deficits were assessed by jointly considering the performance on three semantic tasks that vary in the modalities of input (visual and auditory stimuli) and output (oral naming and associative judgement). We found that the lesion volume and fractional anisotropy value of the left inferior fronto-occipital fasciculus, left anterior thalamic radiation, and left uncinate fasciculus significantly correlated with severity of impairment in all three semantic tasks. These associations remained significant even when we controlled for a wide range of potential confounding variables, including overall cognitive state, whole lesion volume, or type of brain damage. The effects of these three white matter tracts could not be explained by potential involvement of relevant grey matter, and were (relatively) specific to object semantic processing, as no correlation with performance on non-object semantic control tasks (oral repetition and number processing tasks) was observed. These results underscore the causal role of left inferior fronto-occipital fasciculus, left anterior thalamic radiation, and left uncinate fasciculus in semantic processing, providing direct evidence for (part of) the anatomical skeleton of the semantic network.
authors: 1 State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing 100875 China.
authors: Zaizhu
authors: Z
authors: Han
authors: Yujun
authors: Y
authors: Ma
authors: Gaolang
authors: G
authors: Gong
authors: Yong
authors: Y
authors: He
authors: Alfonso
authors: A
authors: Caramazza
authors: Yanchao
authors: Y
authors: Bi
mesh_terms: D000328:Adult; D000368:Aged; D001930:Brain Injuries / Q000473:pathology* / Q000503:physiopathology; D001931:Brain Mapping / Q000379:methods; D056324:Diffusion Tensor Imaging / Q000379:methods; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers / Q000473:pathology*; D009415:Nerve Net / Q000473:pathology*; D009434:Neural Pathways / Q000473:pathology; D009483:Neuropsychological Tests; D055815:Young Adult
keywords: DTI; brain-damaged patient; connectome; semantic network