Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, University College London, London WC1N 3BG, UK.
Cereb Cortex. 2011 Jul;21(7):1627-38. doi: 10.1093/cercor/bhq231. Epub 2010 Dec 1.
Intermittent theta burst stimulation (iTBS) transiently increases motor cortex excitability in healthy humans by a process thought to involve synaptic long-term potentiation (LTP), and this is enhanced by nicotine. Acquisition of a ballistic motor task is likewise accompanied by increased excitability and presumed intracortical LTP. Here, we test how iTBS and nicotine influences subsequent motor learning. Ten healthy subjects participated in a double-blinded placebo-controlled trial testing the effects of iTBS and nicotine. iTBS alone increased the rate of learning but this increase was blocked by nicotine. We then investigated factors other than synaptic strengthening that may play a role. Behavioral analysis and modeling suggested that iTBS increased performance variability, which correlated with learning outcome. A control experiment confirmed the increase in motor output variability by showing that iTBS increased the dispersion of involuntary transcranial magnetic stimulation-evoked thumb movements. We suggest that in addition to the effect on synaptic plasticity, iTBS may have facilitated performance by increasing motor output variability; nicotine negated this effect on variability perhaps via increasing the signal-to-noise ratio in cerebral cortex.
间歇性 theta 爆发刺激（iTBS）通过被认为涉及突触长时程增强（LTP）的过程暂时增加健康人类运动皮层的兴奋性，而尼古丁可增强这种作用。弹道运动任务的获得同样伴随着兴奋性的增加和皮质内 LTP 的假定。在这里，我们测试 iTBS 和尼古丁如何影响随后的运动学习。十名健康受试者参加了一项双盲安慰剂对照试验，以测试 iTBS 和尼古丁的影响。单独的 iTBS 增加了学习速度，但尼古丁阻断了这种增加。然后，我们研究了除突触增强以外可能起作用的其他因素。行为分析和建模表明，iTBS 增加了运动输出的可变性，这与学习结果相关。对照实验通过显示 iTBS 增加了经颅磁刺激诱发的拇指运动的不自主运动的分散，证实了运动输出可变性的增加。我们认为，除了对突触可塑性的影响外，iTBS 还可能通过增加运动输出的可变性来促进表现；尼古丁通过增加大脑皮层的信噪比来否定这种对可变性的影响。
