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| Horizontal visual hemi-field stimulation on single eye in patients with hemianopia: a functional MRI study |
| ZHANG Quan, ZHANG Yun-ting, SONG Xiu-feng, ZHANG Jing, LI Wei |
| Department of Radiology, Tianjin Medical University General Hospital, Tianjin 300052, China |
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Abstract Objective: To observe response of primary visual cortex to horizontal visual hemi-field stimulation on single eye in subjects with hemianopia and to discuss the probability of evaluating the activation of visual cortex with functional MRI(fMRI). Materials and Methods: Thirteen patients with pituitary adenoma and fifteen normal volunteers as control were recruited in this study. Block-designed fMRI was performed with 1.5T MR scanner. Black and white check board(horizontal unilateral 40 degree visual field) and “+” were used as stimulus and control respectively. Bilateral eyes received nasal and temporal side stimulus individually. The fMRI data were processed with SPM 2. Average mappings of subjects were obtained. The relationship between visual field deficits and activation in visual cortex was analyzed for patients group. Results: Ten patients and 10 normal subjects were selected for group analysis after head motion effect was ruled out. In normal subjects, the contralateral occipital lobe showed activation to temporal visual field stimulation and ipsilateral occipital lobe showed activation to nasal visual field stimulation. In patients group, bilateral visual cortex showed no activation to temporal visual field stimulation and ipsilateral occipital lobe showed activation to nasal visual field stimulation. Conclusion: There was a corresponding relationship between visual field and activation of visual cortex in normal subjects. Patients with hemianopia mainly presented with function decrease in contralateral visual cortex. fMRI is an effective method for studying affection of optic chiasm abnormality on visual cortex.
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Received: 06 October 2008
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2009, Vol. 20 
