[Study of functional magnetic resonance imaging repeatability of linguistic-functional cortex].

Objective: To explore the reproducibility and stability of brain functional area in the response of language tasks during Chinese word processing with functional magnetic resonance imaging (fMRI) by follow-up scanning so as to provide rationales for clinical preoperative localization and the mechanisms of recovery from aphasia.
Methods: The fMRI data were collected by scanning semantic and phonologic judgments in 15 healthy volunteers. Each subject was scanned twice by the same fMRI procedure of both language tasks with an interval of 1 month. By analyzing the effective overlapping average activation maps, the reproducibility of inter-subject imaging result for two language tasks were estimated by selecting the main language areas, such as Broca's area and Wernicke's area as the region of interest (ROI). By individually calculating the spatial distance of ROI centroid coordinates in the same activating range before and after test, the inter-subject stability in between-session was calculated quantitatively.
Results: Both language tasks activated more than one language-related brain areas in cerebral hemispheres. Both language tasks induced significant BOLD response in Broca's and Wernicke's areas with a tendency of left lateralization. The number of subjects in terms of the activation of both language tasks in Broca's and Wernicke's areas accounted over a half of the total subjects. As compared with the phonologic judgment task, the semantic judgment task showed better reproducibility in Broca's area. In the same spatial distance of ROI centroid coordinates, the stability of Broca's area was higher than that of Wernicke's area while the stability of semantic judgment in Broca's area higher than that of phonologic judgment.
Conclusion: Such main language domains as Broca's and Wernicke's areas can be effectively activated by both semantic and phonologic judgments. By comparison, semantic judgment in Broca's area shows a higher level of reproducibility and stability. Thus it is applicable for clinical preoperative localization and the mechanisms of recovery from aphasia.