Arnfred Sidse M, Hansen Lars Kai, Parnas Josef, Mørup Morten
Department of Psychiatry, Hvidovre Hospital, University Hospital of Copenhagen, Brøndbyøstervej 160, 2605 Brøndby, Denmark.
Brain Res. 2007 May 25;1147:167-74. doi: 10.1016/j.brainres.2007.02.068. Epub 2007 Mar 3.
A proprioceptive stimulus consisting of a weight change of a handheld load has recently been shown to elicit an evoked potential. Previously, somatosensory gamma oscillations have only been evoked by electrical stimuli. We conjectured that a natural proprioceptive stimulus also would be able to evoke gamma oscillations. EEG was recorded using 64 channels in 14 healthy subjects. In each of three runs a stimulus of 100 g load increment in each hand was presented in 120 trials. Data were wavelet transformed and runs collapsed. Inter-trial phase coherence (ITPC) was computed as the best measure of precision of evoked oscillations. The window of interest was 25-75 Hz and 0-200 ms. ITPC maxima were determined by visual inspection and these results were compared to results of multi-way factor analyses. The predicted 40 Hz activity was observed 60 ms after stimulus onset in the parietal region contralateral to stimulus side and additionally an unexpected 20 Hz activity was observed slightly lateralized in the frontal central region. The gamma phase locking may be a manifestation of early somatosensory feature integration. The analyses suggest that the high frequency activity consists of two distinct underlying oscillatory processes, in need of further investigation.
最近研究表明，由手持负荷重量变化构成的本体感觉刺激能够引发诱发电位。此前，体感伽马振荡仅由电刺激诱发。我们推测自然的本体感觉刺激也能够诱发伽马振荡。使用64个通道对14名健康受试者进行脑电图记录。在三次实验的每一次中，对每只手进行100克负荷增量刺激，共进行120次试验。对数据进行小波变换并合并实验。计算试验间相位相干性（ITPC）作为诱发振荡精度的最佳测量指标。感兴趣的窗口为25 - 75赫兹和0 - 200毫秒。通过目视检查确定ITPC最大值，并将这些结果与多因素分析结果进行比较。在刺激侧对侧的顶叶区域，刺激开始后60毫秒观察到预测的40赫兹活动，此外，在额中央区域稍偏向一侧观察到意外的20赫兹活动。伽马相位锁定可能是早期体感特征整合的一种表现。分析表明，高频活动由两个不同的潜在振荡过程组成，有待进一步研究。
