title: Diffusion tensor imaging depicting damage to the arcuate fasciculus in patients with conduction aphasia: a study of the Wernicke-Geschwind model.
abstract: OBJECTIVE
  In contrast with disorders of comprehension and spontaneous expression, conduction aphasia is characterized by poor repetition, which is a hallmark of the syndrome. There are many theories on the repetition impairment of conduction aphasia. The disconnection theory suggests that a damaged in the arcuate fasciculus, which connects Broca's and Wernicke's area, is the cause of conduction aphasia. In this study, we examined the disconnection theory.
  
  
  METHODS
  We enrolled ten individuals with conduction aphasia and ten volunteers, and analysed their arcuate fasciculus using diffusion tensor imaging (DTI) and obtained fractional anisotropy (FA) values. Then, the results of the left hemisphere were compared with those of the right hemisphere, and the results of the conduction aphasia cases were compared with those of the volunteers.
  
  
  RESULTS
  There were significant differences in the FA values between the left and right hemispheres of volunteers and conduction cases. In volunteers, there was an increase in fiber in the left hemisphere compared with the right hemisphere, whereas there was an increase in fiber in the right hemisphere compared with the left hemisphere in conduction aphasia patients. The results of diffusion tensor tractography suggested that the configuration of the arcuate fasciculus was different between conduction aphasia patients and volunteers, suggesting that there was damage to the arcuate fasciculus of conduction aphasia cases.
  
  
  CONCLUSIONS
  The damage seen in the arcuate fasciculus of conduction aphasia cases in this study supports the Wernicke-Geschwind disconnection theory. A disconnection between Broca's area and Wernicke's area is likely to be one mechanism of conduction aphasia repetition impairment.
authors.affiliation: Beijing Tiantan Hospital, Capital Medical University, Beijing, China.
authors.forename: Yumei
authors.initials: Y
authors.lastname: Zhang
authors.forename: Chunxue
authors.initials: C
authors.lastname: Wang
authors.forename: Xingquan
authors.initials: X
authors.lastname: Zhao
authors.forename: Hongyan
authors.initials: H
authors.lastname: Chen
authors.forename: Zaizhu
authors.initials: Z
authors.lastname: Han
authors.forename: Yongjun
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000328:Adult; D016880:Anisotropy; D018886:Aphasia, Conduction / Q000473:pathology*; D056324:Diffusion Tensor Imaging; D005625:Frontal Lobe / Q000473:pathology*; D007839:Functional Laterality; D006801:Humans; D008297:Male; D008875:Middle Aged; D009434:Neural Pathways / Q000473:pathology; D013702:Temporal Lobe / Q000473:pathology*