Non-invasive measurements of sensory nerve and cortical responses to skin stimulation : Integration of EEG,MEG and fMRI

1. 我们研制了可独立控制的3点空气刺激器，用于激发感觉神经动作电位和体感诱发电位。我们开发了3点振动刺激器，用于研究体感系统中与频率、持续时间和强度感知相关的体感诱发场。我们用高速摄像机观察了空气刺激后皮肤的位移，这些位移与感觉阈值和幅度估计相关。我们通过多通道测量肘部的动作场，可视化了沿正中神经移动的四极杆。在周围神经病变中，我们发现在病变部位或远端电诱发的动作场有一种特殊的振荡模式。我们利用霍奇金-赫胥利方程对振荡进行了计算机模拟，发现Na电导的增加与振荡有关。我们对去皮仔猪三叉神经刺激后的磁场进行了测量，结果表明，皮质下产生的磁场足够强，可以在头外检测到。我们在清醒和睡眠期间测量了N20m的主要响应，随后进行了数字高通（>300 Hz）和低通（>300 Hz）滤波。高频振荡（hfo）的估计来源是与N20m非常接近的区域3b。在睡眠期间，hfo的振幅显著减小，而N20m的振幅则有适度的增加。在清醒-睡眠周期中，hfo和N20m之间的这种互反关系表明它们代表相反的产生底物。我们推测，hfo代表了第4层gaba能抑制性中间神经元的局部活动，在动物实验中已经显示，这些中间神经元对丘脑-皮层输入的高频（600-900 Hz）短持续尖峰的单突触反应。另一方面，底层的N20m代表锥体神经元的活动，锥体神经元接受来自丘脑的单突触兴奋性输入以及来自中间神经元的前馈抑制。我们最近的实验进一步支持了这一假设，即在清醒期间操纵N20m的振幅；hfo和N20m之间的互反关系不仅在清醒-睡眠周期中成立，而且在清醒期间也成立。少

1. We developed 3 point air-puff stimulators which can be controlled independently for eliciting sensory nerve action potentials and somatosensory evoked potentials.2. We developed 3 point vibratory stimulators for studying somatosensory evoked fields associated with perception of frequency, duration and intensity in the somatosensory system.3. We visualized displacements of the skin following air-puff stimulation with a high speed camera which were correlated with a sensory threshold and magnitude estimations.4. We visualized a moving quadrupole along the median nerve with multi-chnnel measurements of action fields over the elbow.5. In peripheral nerve lesions, we found a peculiar oscillation pattern of electrically evoked action fields at or distal to the lesion sites. We performed a computer simulation for the oscillation using the Hodgikin-Huxley equations and found that the increase of Na conductance was related to the oscillation.6. We measured magnetic fields following trigemina … More l stimulation from the decorticated piglets and showed that the subcortically generated fields are strong enough to the detectable outside the head.7. We measured N20m primary response during wakefulness and sleep with subsequent digital high-pass (>300 Hz) and low-pass (>300 Hz) filtering. The estimated source for the high-frequency oscillations (HFOs) was the area 3b very close to that for the N20m. During sleep, the HFOs showed a dramatic diminution in amplitude while the N20m amplitude exhibited a moderate increment. This reciprocal relation between the HFOs and the N20m during a wake-sleep cycle suggests that they represent opposing generator substrates. We speculate that the HFOs represent a localized activity of the GABAergic inhibitory interneurons of layr 4, which have been shown in animal experiments to respond monosynaptically to thalamo-cortical input with a high-frequency (600-900 Hz) burst of short duration spikes. On the other hand, the underlying N20m represents activity of pyramidal neurons which receive monosynaptic excitatory input from the thalamus as well as a feed-forward inhibition from the interneurons. This hypothesis has been further supported by our recent experiments manipulating the amplitude of N20m during wakefulness ; the reciprocal relation between HFOs and N20m hold not only during a wake-sleep cycle but also during wakefulness. Less