纯失读症患者阅读功能恢复机制的功能MRI初步研究

Preliminary study on the mechanism of reading recovery in a pure alexia by using functional MRI

目的 利用磁共振功能成像 (fMRI)技术观察阅读功能恢复过程中脑功能的变化 ,为阐明阅读和语言功能恢复机制提供实验依据。方法 采用fMRI对 1例汉语纯失读症患者在其发病后4 5d和 130d分别进行扫描。在扫描过程中要求病人判断是否认识所呈现的 3类汉字。经后处理获得脑激活图 ,并对 2次实验所观察到的脑激活部位和激活体积等进行比较。结果 第 1次实验显示Broca区、Wernicke区和右侧纹外区等被激活。而在第 2次实验中 ,除上述区域仍被激活外 ,病灶周围的左侧纹外区也见显著激活 ,且右侧纹外区的激活体积比首次实验增大了约 2倍。结论 左侧纹外区皮层是阅读功能的关键脑区之一。阅读功能的恢复既可由对侧相应脑区代偿 ,也可由病灶同侧脑区重组 ,这 2种机制可以并存。

Objective To observe the changes of the brain function during reading recovery by using functional MRI (fMRI),and to provide the experimental data in elucidating the mechanism on the recovery of reading and language function.Methods fMRI was performed in a native Chinese patient with pure alexia on the 45 th and 130 th day after the onset,respectively.Three kinds of Chinese characters were presented during the scan and the patient was asked to make the judgement weather he could recognize the characters or not.The brain activation maps were acquired after postprocessing,and the activated location and volume were compared between the first and second experiments.Results In both experiments,Broca area,Wernicke area,and the right extrastriate were significantly activated,while the left extrastriate around the lesion was markedly activated only in the second experiment,and the volume of activation in the right extrastriate in the second experiment was about 3 times as large as that in the first experiment.Conclusion The left extrastriate cortex is one of the key areas responsible for reading function in the brain.The recovery of reading function can be compensated in contralateral corresponding cortical area,or it can be the result of reorganization in ipsilateral peri-lesion cortex.Both mechanisms may simultaneously play important roles in reading recovery.