Gu Chao, Corneil Brian D
The Brain and Mind Institute, Robarts Research Institute, London, Ontario N6A 5B7, Canada, and Graduate Program in Neuroscience, Department of Psychology, Western University, London, Ontario N6A 5B7, Canada.
The Brain and Mind Institute, Robarts Research Institute, London, Ontario N6A 5B7, Canada, and Department of Physiology & Pharmacology, and Department of Psychology, Western University, London, Ontario N6A 5B7, Canada
J Neurosci. 2014 Oct 29;34(44):14803-15. doi: 10.1523/JNEUROSCI.2907-14.2014.
Transcranial magnetic stimulation (TMS) has emerged as an important technique in cognitive neuroscience, permitting causal inferences about the contribution of a given brain area to behavior. Despite widespread use, exactly how TMS influences neural activity throughout an interconnected network, and how such influences ultimately change behavior, remain unclear. The oculomotor system of nonhuman primates (NHPs) offers a potential animal model to bridge this gap. Here, based on results suggesting that neck muscle activity provides a sensitive indicator of oculomotor activation, we show that single pulses of TMS over the frontal eye fields (FEFs) in awake NHPs evoked rapid (within ∼25 ms) and fairly consistent (∼50-75% of all trials) expression of a contralateral head-turning synergy. This neck muscle response resembled that evoked by subsaccadic electrical microstimulation of the FEF. Systematic variation in TMS location revealed that this response could also be evoked from the dorsolateral prefrontal cortex (dlPFC). Combining TMS with an oculomotor task revealed state dependency, with TMS evoking larger neck muscle responses when the stimulated area was actively engaged. Together, these results advance the suitability of the NHP oculomotor system as an animal model for TMS. The polysynaptic neck muscle response evoked by TMS of the prefrontal cortex is a quantifiable trial-by-trial reflection of oculomotor activation, comparable to the monosynaptic motor-evoked potential evoked by TMS of primary motor cortex. Our results also speak to a role for both the FEF and dlPFC in head orienting, presumably via subcortical connections with the superior colliculus.
经颅磁刺激（TMS）已成为认知神经科学中的一项重要技术，能够对特定脑区对行为的贡献进行因果推断。尽管TMS被广泛应用，但其究竟如何影响整个相互连接网络中的神经活动，以及这种影响最终如何改变行为，仍不清楚。非人灵长类动物（NHPs）的动眼系统提供了一个潜在的动物模型来弥合这一差距。在此，基于表明颈部肌肉活动可作为动眼激活敏感指标的结果，我们发现，在清醒的NHPs中，对额眼区（FEFs）施加单脉冲TMS会诱发对侧转头协同动作的快速（约25毫秒内）且相当一致（约占所有试验的50 - 75%）的表达。这种颈部肌肉反应类似于FEF的次扫视电微刺激所诱发的反应。TMS位置的系统变化表明，这种反应也可从背外侧前额叶皮层（dlPFC）诱发。将TMS与动眼任务相结合揭示了状态依赖性，即当受刺激区域处于活跃状态时，TMS会诱发更大的颈部肌肉反应。总之，这些结果提高了NHPs动眼系统作为TMS动物模型的适用性。前额叶皮层TMS诱发的多突触颈部肌肉反应是动眼激活的一种可逐次量化的反映，类似于初级运动皮层TMS诱发的单突触运动诱发电位。我们的结果还表明FEF和dlPFC在头部定向中均发挥作用，推测是通过与上丘的皮层下连接。
