Division of Neurology, Department of Medicine, University of Toronto and Toronto Western Research Institute, University Health Network, Toronto, Ontario, Canada.
Clin Neurophysiol. 2012 Apr;123(4):815-21. doi: 10.1016/j.clinph.2011.07.051. Epub 2011 Sep 25.
Long-term potentiation (LTP)-like plasticity induced by paired associative stimulation (PAS) is impaired in Parkinson's disease (PD). Intermittent theta burst stimulation (iTBS) is another rTMS protocol that produces LTP-like effects and increases cortical excitability but its effects are independent of afferent input. The aim of the present study was to examine the effects of iTBS on cortical excitability in PD.
iTBS was applied to the motor cortex in 10 healthy subjects and 12 PD patients ON and OFF dopaminergic medications. Motor evoked potential (MEP) before and for 60 min after iTBS were used to examine the changes in cortical excitability induced by iTBS. Paired-pulse TMS was used to test whether intracortical circuits, including short interval intracortical inhibition, intracortical facilitation, short and long latency afferent inhibition, were modulated by iTBS.
After iTBS, the control, PD ON and OFF groups had similar increases in MEP amplitude compared to baseline over the course of 60 min. Changes in intracortical circuits induced by iTBS were also similar for the different groups.
iTBS produced similar effects on cortical excitability for PD patients and controls.
Spike-timing dependent heterosynaptic LTP-like plasticity induced by PAS may be more impaired in PD than frequency dependent homosynaptic LTP-like plasticity induced by iTBS.
配对联想刺激（PAS）诱导的长时程增强（LTP）样可塑性在帕金森病（PD）中受损。间歇性 theta 爆发刺激（iTBS）是另一种 rTMS 方案，可产生类似 LTP 的效应并增加皮质兴奋性，但它的作用独立于传入输入。本研究的目的是研究 iTBS 对 PD 皮质兴奋性的影响。
在 10 名健康受试者和 12 名 PD 患者 ON 和 OFF 多巴胺能药物时，将 iTBS 应用于运动皮层。在 iTBS 前后使用运动诱发电位（MEP）来检查 iTBS 诱导的皮质兴奋性变化。使用成对脉冲 TMS 来测试包括短间隔皮质内抑制、皮质内易化、短潜伏期和长潜伏期传入抑制在内的皮质内回路是否被 iTBS 调制。
在 iTBS 后，与基线相比，对照、PD ON 和 OFF 组在 60 分钟的过程中 MEP 幅度均有相似的增加。不同组之间，iTBS 诱导的皮质内回路变化也相似。
iTBS 对 PD 患者和对照组的皮质兴奋性产生相似的影响。
与 iTBS 诱导的频率依赖性同突触 LTP 样可塑性相比，PAS 诱导的依赖于尖峰时间的异突触 LTP 样可塑性在 PD 中可能受损更严重。
