旋转光栅视觉刺激生理成分的功能MRI研究

目的利用功能磁共振成像(fMRI)技术，观察旋转光栅刺激引起的视觉皮层生理反应，探索其反应的组成成分。方法9例健康志愿者，以旋转光栅、静止光栅和白光为任务状态，静止光栅、白光和黑暗为控制状态，任务设置分为6个步骤；采用1．5T磁共振扫描仪，梯度回波基础上加平面回波(GRE-EPI)成像序列采集数据，SPM99软件进行数据离线后处理，数据采用单样本处理。结果旋转光栅的各种刺激成分引起不同视觉皮层中枢的兴奋。枕叶中央区域的强烈反应位于初级视觉皮层区，平均坐标为13、-98、-2与11、-100、-4，与白光刺激有关。两侧19区的反应位于枕颞交界处的MT区，平均坐标为、46、-72、-2与-44、-74、0，与视觉运动功能有关。枕叶中央微弱的反应区的平均坐标为-12、-98、-6与-16、-96、-6，与形状察觉功能有关。结论在组块设计时，控制状态的设计起着重要的作用。旋转光栅刺激可以提供单纯光感觉、视觉运动及形状察觉信息成分。fMRI技术可以作为研究视皮层生理的良好工具。

Study of physiology of visual cortex activated by rotating grating with functional MRI

Objective To research the physiology of visual cortex activated by rotating grating with functional-MRI(fMRI), and to identify the components of the activation. Methods Functional MRI was performed in 9 healthy volunteers by using GRE-EPI sequences on a 1.5 T MR scanner. In the block designing, rotating grating, static grating, and luminance were plotted as task states, while static grating, luminance, and darkness were set as control states. The stimuli tasks included six steps. Imaging processing and statistical analysis was carried out off-line using SPM99 in single-subject method. Results Some respective areas of visual cortex were activated by the various stimuli information supplied by rotating grating. The strong activation in the middle of occipital lobe located at primary vision area was related to the stimuli of white luminance. Its average maximum points were at 13,-98,-2 and 11, -100,-4. The bilateral activations of Brodmann 19th area located at MT area were related to visual motion perception. Its average maximum points were at 46,-72,-2 and -44,-74, 0. The mild activation in the middle of occipital lobe was related to form perception. Its average maximum points were at -12,-98,-6 and -16,-96, (-6.) Conclusion The plotting of control state is important in bock design. The effective visual information of rotating grating includes components of luminance, visual motion perception, and form perception. FMRI has potential as a tool for studying the basic physiology of visual cortex.