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目的分析全、半及四分视野图形刺激的视觉诱发磁场反应特点及其所对应等电流偶极源的确切位置。方法分别测试13名受试者对全、左半、右半、左上、左下、右上及右下四分视野的视觉诱发磁场反应,分析其潜伏期、偶极矩及偶极在x、y、z轴上的位置关系,并通过磁源成像精确定位不同视野图形刺激所引起视觉诱发磁场的位置。结果全视野可引起双侧枕叶的双偶极模式兴奋。双偶极模式的2个偶极潜伏期相同,偶极强度(偶极矩)不同。与MR图像叠加后,所有13个M100偶极出现在包括楔上回、楔下回、楔舌后回、舌上回、舌下回、楔前回及小脑蚓部在内的皮层区。半及四分视野刺激会在刺激野的对侧半球枕区引起单偶极模式的兴奋。半视野刺激所得26个M100偶极位于舌上回、楔下回、楔舌后回和舌下回。35个四分视野刺激M100偶极分布于舌上回、舌下回、楔下回和楔舌后回。对8例受试者的32个四分视野M100偶极在x、y、z轴上的位置X、Y、Z值进行了统计学处理,发现左上四分视野M100偶极Z值中位数为49.6(35.1~72.8)mm,左下四分视野M100偶极Z值中位数为53.5(44.8~76.3)mm,二者差值为3.9 mm,差异有统计学意义(P<0.05);右上四分视野M100偶极Z值中位数为40.0(34.8~44.6)mm,右下四分视野M100偶极Z值中位数为53.8(40.6~61.3)mm,二者差值为13.8 mm,差异有统计学意义(P<0.05)。提示下四分视野刺激的M100偶极较上四分视野刺激时高。M100源位置与MR图像叠加后,主要位于包括舌上回、楔舌后回及楔下回在内的B rodm ann 17区。结论图形刺激视觉诱发磁场反应中的M100兴奋主要由纹状皮层的神经元产生,而且更偏向后方,即主要皮层反应位于刺激野对侧半球枕区的距状沟底部后方。
OBJECTIVE: To analyze the characteristics of visual-induced magnetic field response of all, half, and four-field visual stimuli and the exact location of the corresponding galvanic dipole sources. Methods Thirteen subjects were tested for visual evoked magnetic field response to the full, left half, right half, left upper, lower left, upper right and lower right four fields respectively. The latency, dipole moment and dipole were analyzed in x, y, z Axis position, and through magnetic imaging to accurately locate the different visual field stimuli caused by visual-induced magnetic field position. Full field of view results in excitement of the double dipole pattern of bilateral occipital lobes. Two dipoles in dipole mode have the same dipole duration and different dipole strengths (dipole moments). After superposition with the MR images, all 13 M100 dipoles appeared in the cortical region including upper wedge, lower wedge back, back wedge back, upper tongue back, sublingual back, wedge anterior and cerebellar vermis. Half and quarter field stimuli cause excitement in single dipole mode in the contralateral hemispheric occipital region of the stimulating field. Sixty-six M100 dipoles were obtained from the half-field stimulation at the supraspinalis, wedge back, back of the wedge tongue, and sublingual back. Thirty-five quarter-fields stimulated M100 dipoles to be distributed on the tongue, back to the tongue, back to the wedge and back to the wedge tongue. The X, Y, Z values of 32 field cents M100 dipoles of 8 subjects in the x, y, z axes were statistically analyzed and the median M100 dipole Z value of the upper left quadrant was found Was 49.6 (35.1-72.8) mm. The median Z-dipolar Z of M100 in the left lower quadrant was 53.5 (44.8-76.3) mm, with a difference of 3.9 mm between the two groups (P <0.05) The median M of the M100 dipole Z was 40.0 (34.8-44.6) mm in the fourth field of view and 53.8 (40.6-61.3) mm in the lower right field of view. The difference between the two was 13.8 mm, The difference was statistically significant (P <0.05). Tips M400 dipole quadrant under the stimulus of the upper quadrant of the field when the dipole stimulation. The M100 source is superimposed on the MR image, mainly in the B rodm ann 17 zone, including the supraspinalis, the wedge back and the inferior wedge. CONCLUSIONS: M100 excitability in the visual stimulus-induced magnetic field response is mainly generated by neurons in the striatum cortex and more posteriorly, ie, the main cortical response is located behind the bottom of the ditch in the contralateral hemispheric area of the stimulation field.