Objectives

To investigate the subcortical somatosensory evoked potentials (SEPs) to electrical stimulation of either muscle or cutaneous afferents.

Methods

SEPs were recorded in 6 patients suffering from Parkinson’s disease (PD) who underwent electrode implantation in the pedunculopontine (PPTg) nucleus area. We compared SEPs recorded from the scalp and from the intracranial electrode contacts to electrical stimuli applied to: 1) median nerve at the wrist, 2) abductor pollicis brevis motor point, and 3) distal phalanx of the thumb. Also the high-frequency oscillations (HFOs) were analysed.

Results

After median nerve and pure cutaneous (distant phalanx of the thumb) stimulation, a P1-N1 complex was recorded by the intracranial lead, while the scalp electrodes recorded the short-latency far-field responses (P14 and N18). On the contrary, motor point stimulation did not evoke any low-frequency component in the PPTg traces, nor the N18 potential on the scalp. HFOs were recorded to stimulation of all modalities by the PPTg electrode contacts.

Conclusions

Stimulus processing within the cuneate nucleus depends on modality, since only the cutaneous input activates the complex intranuclear network possibly generating the scalp N18 potential.

Significance

Our results shed light on the subcortical processing of the somatosensory input of different modalities.

中文翻译：

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不同体感传入输入对人类皮层下体感诱发电位的贡献

目标

研究皮层下体感诱发电位 (SEP) 对肌肉或皮肤传入神经的电刺激。

方法

在 6 名帕金森氏病 (PD) 患者中记录了 SEP，他们在脚桥 (PPTg) 核区接受了电极植入。我们比较了从头皮和颅内电极接触记录的 SEP 与应用于：1) 腕部正中神经，2) 拇短展肌运动点，和 3) 拇指远端指骨的电刺激。还分析了高频振荡 (HFO)。

结果

在正中神经和纯皮肤（拇指远方指骨）刺激后，颅内导线记录到 P1-N1 复合体，而头皮电极记录短延迟远场响应（P14 和 N18）。相反，运动点刺激不会在 PPTg 迹线中引起任何低频分量，也不会在头皮上引起 N18 电位。通过 PPTg 电极触点记录 HFO 对所有方式的刺激。

结论

楔形核内的刺激处理取决于模式，因为只有皮肤输入激活复杂的核内网络，可能会产生头皮 N18 电位。

意义

我们的结果阐明了不同方式的体感输入的皮层下处理。