Analysis of processing in somatosensory input by using MEG

研究了对右手食指指尖和双侧双手进行两点触觉刺激后的皮层激活情况。我们使用了一个306英寸的全头部脑磁图系统和一个由压电致动器驱动的触觉刺激器。该刺激器的两个微型塑料针阵列被用来获得体感诱发磁场（SEF）。在固定距离刺激条件下，所有受试者都能清晰地察觉到针脚之间的距离为7.2mm；在两点辨别条件下，针脚之间的距离为2.4mm、4.8mm和7.2mm。在2PD条件下，随机给予三种刺激。同时给予双侧手刺激。我们证实了在单侧和双侧刺激条件下，左半球体感觉皮层周围有三个SEF波形峰。在两种情况下，单侧和双侧刺激的峰值潜伏期没有显著差异。双侧刺激时，第2、3峰的振幅明显增加。与这些峰相对应的ecd位于3b区后方。

We investigated the cortical activation following two points tactile stimulation to tip of index finger of right hand and bilateral hands. We used a 306-ch whole-head MEG system and a tactile stimulator driven by piezoelectrical actuator. An array of two tiny plastic pins of the stimulator was used to obtain the somatosensory evoked magnetic fields (SEF). The distance between pins was set at 7.2mm that all subjects detect clearly for constant distance stimuli condition and at2.4mm, 4.8mm and 7.2mm for two points discrimination (2PD condition). In 2PD condition, three kinds of stimulation were given randomly. The stimulation to bilateral hand was given simultaneously. We confirmed three peaks of SEF waveforms around the somatosensory cortex in the left hemispheres in both conditions in unilateral and bilateral stimulations. There were no significant differences in the peak latencies in both conditions between unilateral and bilateral stimulations. The second and third peaks in 2Pcondition in bilateral stimulations increased in amplitude significantly. The ECDs corresponding to these peaks were located in posterior portion from area 3b.