Mäkelä J P, Hämäläinen M, Hari R, McEvoy L
Low Temperature Laboratory (LTL), Helsinki University of Technology, Espoo, Finland.
Electroencephalogr Clin Neurophysiol. 1994 Sep;92(5):414-21. doi: 10.1016/0168-5597(94)90018-3.
We recorded middle-latency auditory evoked magnetic fields from 9 healthy subjects with a 122-channel whole-head SQUID gradiometer. The stimuli were click triplets, 2.5 msec in total duration, delivered alternately to the two ears once every 333 msec. Contralateral clicks elicited P30m responses in 16 and P50m responses in 12 out of 18 hemispheres studied; ipsilateral clicks did so in 7 and 13 hemispheres, respectively. The field patterns were satisfactorily explained by current dipoles in 16 and 4 hemispheres for contra- and ipsilateral P30m, and in 4 and 10 hemispheres for contra- and ipsilateral P50m. The peak latencies of P30m and P50m were not affected by stimulation side. The results show that middle-latency auditory evoked responses receive a strong contribution from auditory cortical structures, and that differences of input latency to cortical auditory areas, evaluated from MLAEF latencies, do not explain the latency differences seen in late auditory evoked fields to contralateral vs. ipsilateral stimulation.
我们用一台122通道全头型超导量子干涉仪梯度计记录了9名健康受试者的中潜伏期听觉诱发磁场。刺激为三联短声，总时长2.5毫秒，每333毫秒交替刺激双耳一次。在所研究的18个半球中，对侧短声在16个半球中引出了P30m反应，在12个半球中引出了P50m反应；同侧短声分别在7个和13个半球中引出了上述反应。对于对侧和同侧P30m，分别在16个和4个半球中，以及对于对侧和同侧P50m，分别在4个和10个半球中，电流偶极子能令人满意地解释磁场模式。P30m和P50m的峰潜伏期不受刺激侧的影响。结果表明，中潜伏期听觉诱发反应很大程度上源自听觉皮质结构，并且从磁源性听觉诱发电位潜伏期评估的听觉皮质区域输入潜伏期差异，无法解释在晚期听觉诱发电场中对侧与同侧刺激所见的潜伏期差异。
