【摘要】 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。更多还原

【Abstract】 Objective To have acknowledgement of characteristics of normal volunteers′ visual evoked fields about full field,vertical half field and quadrant field and their dipole location by magnetoencephalography.Methods The visual evoked fields of full field,vertical half field and quadrant field were detected with 13 subjects.The latency,dipole strength and dipoles′ location on x,y and z axis were analyzed.The exact locations of the dipoles were detected by overlapping on MR images.Results The isocontour map of M100 of full field stimulation demonstrated two separate sources.The two M100 dipoles had same peak latency and different strength.And for vertical half field and quadrant field stimulation,evoked magnetic fields of M100 distributed contralateral to the stimulated side.The M100 dipoles on the(z-axis) to the lower quadrant field stimulation were located significantly higher than those to the upper quadrant field stimulation.The Z value median of left upper quadrant was 49.6(35.1-72.8)mm.The Z value median of left lower quadrant was 53.5(44.8-76.3)mm.The different of two left quadrant medians,3.9 mm,was significant(P<0.05).The Z value median of right upper quadrant was 40.0(34.8-44.6)mm.The Z value median of right lower quadrant was 53.8(40.6-61.3)mm.The different of two right quadrant medians,13.8 mm,was also significant(P<0.05).Although each of the visual evoked fields waveforms and dipole locations demonstrated large intra-and inter-individual variations,the dipole of M100 was mainly located at area Brodmann 17,which includes superior lingual gyrus,posterior cuneus-lingual gyrus and inferior cuneus gyrus.Conclusion The M100 of visual evoked fields of pattern reversal stimulation is mainly generated by the neurons of striate cortex of contralateral to the stimulated side,which is at the lateral bottom of the calcarine fissure.更多还原