The Visual Processing Of Words And Object Shapes: An FMRI Study

The present study aimed to explore the similarity and difference of neural mechanism of word and object during visual processing with fMRI. The experimental materials adopted in the study were four kinds of representation icons representing the same object with different visual features, which refer to Chinese character, English, line drawing and colored picture, and the chessboard was used as control material. The size judgement was selected as task to limit the influence of phonological and semantic processing. As to the statistical processing, the method of ROI was adopted to investigate the activation of Chinese character, English, line drawing and colored picture in occipital-fusiform and left fusiform based on the whole-brain activation, which could help to define more accurate activation location of four kinds of stimulus during visual processing. The main results of this study as follows:1. In the whole-brain activation, the visual processing of words and objects activated a large scale of brain areas that were involved in visual spatial structure processing, including the right middle frontal gyrus, right inferior frontal gyrus and bilateral inferior parietal lobule.2. In the occipital-fusiform ROI, word form and object shape processing showed different processing patterns. In detail, the word form processing of English was processed in bilateral fusiform, while the word form processing of Chinese character was not only processed in bilateral fusiform, but also in the right occipital lobe. The activation in occipital lobe should be related with the typical graphical feature of Chinese character. Compared with the object shape processing, the activation of Chinese character in the left fusiform was more significant. The visual processing of object shape was mainly in the right occipital lobe and fusiform, showing the right lateralization.3. In the bilateral fusiform ROI, the activation intensity of Chinese character and line drawing showed left lateralization, while the activation intensity of English and colored picture showed right lateralization. The different lateralization between Chinese character and English implied that the left brain areas were mainly involved in the visual processing of the first language, and the visual processing of the second language was mainly processed in right brain areas. The different lateralization between line drawing and colored picture indicated that the function of left and right fusiform was different, the right fusiform play a more important role in specific visual feature information processing.Comparing Chinese character with alphabetic writing and object shape respectively, it was found that the visual processing pattern of Chinese character showed both languge and graphical features. It may be due to its own independent word form representation system and the typical graphical visual structure. The results of this study was significant to some extend for solving the problem of learning difficulties resulting from the visual processing and the treatment and rehabilitation of patients with brain injury.