Lenz F A, Jaeger C J, Seike M S, Lin Y C, Reich S G
Department of Neurosurgery, Johns Hopkins Hospital, Baltimore, Maryland 21278-7713, USA.
J Neurophysiol. 2002 Apr;87(4):2084-94. doi: 10.1152/jn.00049.2001.
Tremor that occurs as a result of a cerebellar lesion, cerebellar tremor, is characteristically an intention tremor. Thalamic activity may be related to cerebellar tremor because transmission of some cerebellar efferent signals occurs via the thalamus and cortex to the periphery. We have now studied thalamic neuronal activity in a cerebellar relay nucleus (ventral intermediate-Vim) and a pallidal relay nucleus (ventralis oral posterior-Vop) during thalamotomy in patients with intention tremor and other clinical signs of cerebellar disease (tremor patients). The activity of single neurons and the simultaneous electromyographic (EMG) activity of the contralateral upper extremity in tremor patients performing a pointing task were analyzed by spectral cross-correlation analysis. EMG spectra during intention tremor often showed peaks of activity in the tremor-frequency range (1.9-5.8 Hz). There were significant differences in thalamic neuronal activity between tremor patients and controls. Neurons in Vim and Vop had significantly lower firing rates in tremor patients than in patients undergoing thalamic surgery for pain (pain controls). Other studies have shown that inputs to Vim from the cerebellum are transmitted through excitatory connections. Therefore the present results suggest that tremor in these tremor patients is associated with deafferentation of the thalamus from cerebellar efferent pathways. The thalamic X EMG cross-correlation functions were studied for cells located in Vim and Vop. Neuronal and EMG activity were as likely to be significantly correlated for cells in Vim as for those in Vop. Cells in Vim were more likely to have a phase lag relative to EMG than were cells in Vop. In monkeys, cells in the cerebellar relay nucleus of the thalamus, corresponding to Vim, are reported to lead movement during active oscillations at the wrist. In view of these monkey studies, the present results suggest that cells in Vim are deafferented and have a phase lag relative to tremor that is not found in normal active oscillations. The difference in phase of thalamic spike X EMG activity between Vim and Vop may contribute to tremor because lesions of pallidum or Vop are reported to relieve cerebellar tremor.
由小脑病变引起的震颤，即小脑震颤，其典型特征为意向性震颤。丘脑活动可能与小脑震颤有关，因为一些小脑传出信号是通过丘脑和皮层传至外周的。我们现在研究了意向性震颤及其他小脑疾病临床体征患者（震颤患者）在丘脑切开术中，小脑中继核（腹中间核-Vim）和苍白球中继核（口后腹核-Vop）的丘脑神经元活动。通过频谱互相关分析，对震颤患者在执行指向任务时单个神经元的活动以及对侧上肢同时的肌电图（EMG）活动进行了分析。意向性震颤期间的肌电图频谱在震颤频率范围（1.9 - 5.8赫兹）内常显示出活动峰值。震颤患者与对照组之间丘脑神经元活动存在显著差异。与因疼痛接受丘脑手术的患者（疼痛对照组）相比，震颤患者Vim和Vop中的神经元放电率显著更低。其他研究表明，小脑至Vim的输入通过兴奋性连接进行传递。因此，目前的结果表明，这些震颤患者的震颤与小脑传出通路导致的丘脑传入缺失有关。研究了位于Vim和Vop的细胞的丘脑X肌电图互相关函数。Vim中的细胞与Vop中的细胞相比，神经元活动和肌电图活动同样可能显著相关。Vim中的细胞比Vop中的细胞更有可能相对于肌电图存在相位滞后。在猴子中，据报道，丘脑的小脑中继核中对应于Vim的细胞在手腕主动振荡期间会领先于运动。鉴于这些猴子研究，目前的结果表明，Vim中的细胞传入缺失，并且相对于正常主动振荡中未发现的震颤存在相位滞后。Vim和Vop之间丘脑尖峰X肌电图活动的相位差异可能导致震颤，因为据报道苍白球或Vop的损伤可缓解小脑震颤。
