Comparative study of human retinotopy using MEG and fMRI

为了在活体内可视化人类视网膜复制，我们比较了视觉诱发磁场(VEFS)中P100m偶极子的来源位置与功能磁共振成像(FMRI)结合EPI方法获得的激活区。对5名正常受试者的左右半视野、上、下象限进行棋盘翻转图形刺激。采用岛津公司(Shimadzu Co.，SBI-100)129通道矢量神经磁成像系统记录VEF。常规1.5T磁共振成像机用平面回波序列对同一受试者进行功能磁共振成像。在半场刺激中，P100m的起源位置被估计在对侧距骨沟。等值电流偶极子(ECD)在下象限刺激中位于距骨沟以下。在fMRI中，半场刺激的激活区位于对侧距骨裂下方的舌回。而象限刺激的激活区位于对侧舌侧回的后部。我们的结果表明，ECDs在模式反转VEFS中的位置与fMRI中的激活区大致一致。P100m来源定位的可靠性必须通过fMRI研究来加强。

ABSTRACT.In order to visualize the human retinotopy in vivo we compared the source location of P100m dipoles in visual evoked magnetic fields (VEFs) with the activated area obtained by functional magnetic resonance imaging (fMRI) with EPI method. Checkerboard reversal pattern stimulation was presented to the left and right hemifields, and to the upper and lower quadrant fields of five normal subjects. VEF were recorded using a 129-channel vector neuromagnetic imaging system (Shimadzu Co., SBI-l00). fMRI was obtained by a conventional 1.5T MRI scanner from the same subject using echo planar imaging sequence. In half-field stimulation, the source location of P100m was estimated on the contralateral calcarine sulcus. The location of equivalent current dipole (ECD) in lower quadrant stimuli was below calcarine sulcus. In fMRI, the activated area in half-field stimuli was situated in the lingual gyrus below the contralateral calcarine fissure. However, the activated areas in quadrant stimuli were situated around the posterior part of the contralateral lingual gyrus. Our results show that the locations of ECDs in pattern reversal VEFs roughly agree with the activated area in fMRI.The reliability of source localization of P100m must be reinforced by a fMRI study.