Hua Sherwin E, Lenz Frederick A
Department of Neurosurgery, Meyer Bldg. 8-161, Johns Hopkins Hospital, 600 N. Wolfe St., Baltimore, MD 21287, USA.
J Neurophysiol. 2005 Jan;93(1):117-27. doi: 10.1152/jn.00527.2004. Epub 2004 Aug 18.
The mechanism of essential tremor (ET) is unclear. Animal models of tremor and functional imaging studies in ET predict that the cerebellum and a cerebellar recipient thalamic nucleus (ventral intermediate, Vim) should exhibit oscillatory activity during rest and during tremor due to abnormal olivo-cerebellar activity. Physiologic responses of 152 single neurons were recorded during awake mapping of the ventral thalamus in seven patients with ET prior to thalamotomy. During postural tremor, spectral cross-correlation analysis demonstrated that 51% of the neurons studied exhibited a concentration of power at tremor frequency that was correlated with electromyography, i.e., tremor neurons. During rest, thalamic neurons did not exhibit tremor-frequency activity. Among the three thalamic nuclei surveyed, Vim had a significantly higher proportion of tremor neurons than did the principal somatic sensory nucleus (ventral caudal, Vc) or a pallidal recipient thalamic nucleus (ventral oral posterior, Vop). Neurons related to active movement (voluntary neurons) had significantly greater tremor-related activity than did nonvoluntary neurons. These findings are not consistent with a model of continuous olivo-cerebellar driving of the motor cortex through thalamic connections. Instead ET may be facilitated by motor circuits that enable tremor-related thalamic activity during voluntary movement. Additionally, a subgroup of tremor neurons with proprioceptive inputs were identified that may allow sensory feedback to access the central tremor network.
特发性震颤（ET）的发病机制尚不清楚。震颤的动物模型以及ET的功能成像研究预测，由于橄榄小脑活动异常，小脑和一个小脑传入丘脑核（腹中间核，Vim）在静息期和震颤期应表现出振荡活动。在7例接受丘脑切开术的ET患者丘脑腹侧清醒标测期间，记录了152个单神经元的生理反应。在姿势性震颤期间，频谱互相关分析表明，所研究的神经元中有51%在震颤频率处表现出功率集中，且与肌电图相关，即震颤神经元。在静息期，丘脑神经元未表现出震颤频率活动。在所调查的三个丘脑核中，Vim的震颤神经元比例显著高于主要躯体感觉核（腹尾核，Vc）或苍白球传入丘脑核（腹口后核，Vop）。与主动运动相关的神经元（随意神经元）的震颤相关活动明显高于非随意神经元。这些发现与通过丘脑连接对运动皮层进行持续橄榄小脑驱动的模型不一致。相反，ET可能由在随意运动期间使震颤相关丘脑活动得以发生的运动回路促成。此外，还识别出了一组具有本体感觉输入的震颤神经元亚群，这可能使感觉反馈能够接入中枢震颤网络。
