磁源性影像对初级听觉皮质定位的研究

Localization of the human primary auditory cortex by magnetic source imaging

目的 应用磁源性影像对健康受试者进行初级听觉皮质定位 ,研究磁源性影像对听觉皮质定位的价值。方法 使用 3 0 6通道全头型生物磁仪 (脑磁图 ,MEG)测量 9例右利手健康受试者的听觉皮质磁诱发反应 ,其中男 7例 ,女 2例 ,年龄 14～ 47岁 ,平均 3 1岁。给予受试者双耳纯音刺激 ,声音频率 2kHz,强度 90dB声压级 (SPL) ,声音持续时间为 8ms,刺激时间间隔为 1s。将MEG测得的磁反应信息叠加到MRI获得磁源性影像 (MSI) ,确定初级听觉皮质的位置。结果 所有受试者均出现M5 0、M10 0、M15 0及M2 0 0 (给予双耳听觉刺激后 ,分别于 5 0、10 0、15 0、2 0 0ms左右出现的听觉诱发磁场波峰 )。将M5 0、M10 0叠加到MRI,其等电流偶极 (ECD)位置均在双侧颞横回 ,为初级听觉皮质的位置。所有受试者中 ,M10 0左、右侧半球ECD位置最大差值x轴为 19 1mm ,y轴为 2 0 7mm ,z轴为7 1mm。M5 0左、右侧半球ECD位置最大差值x轴为 2 0 0mm ,y轴为 2 1 2mm ,z轴为 7 6mm。同一受试者M5 0波峰ECD位置与相应半球的M10 0波峰ECD位置极为接近 ,在统计学上无显著性差异 (P >0 0 5 ) ,其最大差值x轴为 3 3mm ,y轴为 2 0mm ,z轴为 1 2mm。经统计学处理 ,本组受试者左、右侧初级听觉皮质位置无显著性差异 (P >0 0 5 )。结论 应用磁?

Objective To localize the primary auditory cortex of healthy subjects by magnetic source imaging (MSI), and to study the value of MSI in mapping the auditory cortex of healthy subjects. Methods Nine right handed healthy subjects were examined by 306 channel whole scalp magnetoencephalography (MEG) and 1 5 T MR unit. The subjects included 7 men and 2 women, aged 14 to 47 years (average 31 years). The pure tone stimuli were given to the left and right ears in all subjects with the intensity of 90 dB (sound pressure level, SPL) and frequency of 2 kHz. The pure tone lasted for 8 ms, and the inter stimulus interval (ISI) was 1 s. The functional brain activity was evoked and the primary auditory cortex was excited. The excited cortex generated a weak magnetic field out of the brain, which could be measured by MEG. The location the primary auditory cortex was observed after superimposing the MEG data on MRI. Results M50, M100, M150, and M200 (M50, M100, M150, and M200 were the auditory evoked responses occurred at about 50 ms, 100 ms, 150 ms, and 200 ms, respectively after the auditory stimuli) appeared in all subjects. After M50 and M100 were superimposed on MRI, respectively, the equivalent current dipole (ECD) was located at bilateral transverse temporal gyri, corresponding to the primary auditory cortex. The maximal differences of the ECD of M100 between the bilateral hemispheres were 19.1 mm in x axis, 20.7 mm in y axis, and 7.1 mm in z axis. The maximal differences of the ECD of M50 between the bilateral hemispheres were 20.0 mm in x axis, 21.2 mm in y axis, and 7.6 mm in z axis. The ECD locations of the M50 and M100 were quite near in the same subject′ s corresponding hemisphere( P >0.05). The biggest differences between M50 and M100 in the same subject′s corresponding hemisphere were 3.3 mm in x axis, 2.0 mm in y axis, and 1.2 mm in z axis. The location of primary auditory cortex had no significant difference between bilateral hemispheres among the subjects( P >0.05). Conclusions The primary auditory cortex could be precisely localized by MSI.