Division of Biology and Computation and Neural Systems, California Institute of Technology, Pasadena, California 91125.
J Neurosci. 2013 Oct 16;33(42):16684-97. doi: 10.1523/JNEUROSCI.2675-13.2013.
Recent studies have demonstrated that strong neural modulations can be evoked with optogenetic stimulation in macaque motor cortex without observing any evoked movements (Han et al., 2009, 2011; Diester et al., 2011). It remains unclear why such perturbations do not generate movements and if conditions exist under which they may evoke movements. In this study, we examine the effects of five optogenetic constructs in the macaque frontal eye field and use electrical microstimulation to assess whether optical perturbation of the local network leads to observable motor changes during optical, electrical, and combined stimulation. We report a significant increase in the probability of evoking saccadic eye movements when low current electrical stimulation is coupled to optical stimulation compared with when electrical stimulation is used alone. Experiments combining channelrhodopsin 2 (ChR2) and electrical stimulation with simultaneous fMRI revealed no discernible fMRI activity at the electrode tip with optical stimulation but strong activity with electrical stimulation. Our findings suggest that stimulation with current ChR2 optogenetic constructs generates subthreshold activity that contributes to the initiation of movements but, in most cases, is not sufficient to evoke a motor response.
最近的研究表明，在不观察到任何诱发运动的情况下，利用光遗传学刺激可以在猕猴运动皮层中引起强烈的神经调制（Han 等人，2009 年，2011 年；Diester 等人，2011 年）。目前尚不清楚为什么这些干扰不会产生运动，以及是否存在可以诱发运动的条件。在这项研究中，我们检查了五种光遗传学构建体在猕猴额眼区的作用，并使用电微刺激来评估光学局部网络的干扰是否会导致光学、电和联合刺激期间可观察到的运动变化。我们报告说，与单独使用电刺激相比，当低电流电刺激与光刺激结合使用时，诱发扫视眼运动的概率显著增加。将通道视紫红质 2（ChR2）与电刺激结合并同时进行 fMRI 的实验表明，在光刺激时电极尖端没有可识别的 fMRI 活动，但电刺激时有强烈的活动。我们的发现表明，当前 ChR2 光遗传学构建体的刺激会产生亚阈值活动，有助于运动的启动，但在大多数情况下，不足以引起运动反应。
