Moraitis Timoleon, Ghosh Arko
Institute of Neuroinformatics, University of Zurich and ETH Zurich, Winterthurerstr. 190, Zurich CH-8057, Switzerland.
Institute of Neuroinformatics, University of Zurich and ETH Zurich, Winterthurerstr. 190, Zurich CH-8057, Switzerland; Neuroscience Center Zurich, University of Zurich and ETH Zurich, Switzerland; Institute of Cognitive Neuroscience, University College London, United Kingdom.
Neuropsychologia. 2014 Dec;65:279-86. doi: 10.1016/j.neuropsychologia.2014.09.010. Epub 2014 Sep 16.
Involuntary movements such as spontaneous eye blinks can be successfully inhibited at will. Little do we know how the voluntary motor circuits countermand spontaneous blinks. Do the voluntary inhibitory commands act to pause or to turn off the endogenous blink generator, or does inhibition intersect and counter the generator׳s excitatory outputs? In theory, the time taken for the system to generate an after-inhibition blink will reflect onto the form of inhibition. For instance, if voluntary commands were to turn the blink generator off then the after-blink latency would be fixed to the inhibition offset and reflect the time it takes for the generator to rebound and turn on. In this study we measured the after-blink latency from the offset of voluntary inhibition. Volunteers inhibited their blinks in response to sound tones of randomly varying durations. At the offset volunteers withdrew the inhibition and relaxed. Interestingly, the spontaneous after-blinks were fixed to the offset of the inhibition as if the generator rebounded from an off state. The after-blink latency was not related to the duration of the inhibition, and inhibiting even for a small fraction of the mean inter-blink interval generated an after-blink time-locked to the inhibition offset. Interestingly, the insertion of voluntary blinks after inhibition further altered the blink generator by delaying the spontaneous after-blinks. We propose that the inhibition of spontaneous blinks at the level of the generator allows for highly effective voluntary countermanding. Nevertheless, the withdrawal of such inhibition was strongly associated with motor excitation.
诸如自发眨眼之类的不自主运动可以被随意成功抑制。我们对自主运动回路如何撤销自发眨眼知之甚少。自主抑制指令是起到暂停还是关闭内源性眨眼发生器的作用，或者抑制作用是否与发生器的兴奋性输出相交并对抗它呢？理论上，系统产生抑制后眨眼所需的时间将反映在抑制形式上。例如，如果自主指令关闭眨眼发生器，那么眨眼后潜伏期将固定为抑制结束时间，并反映发生器恢复并开启所需的时间。在本研究中，我们测量了从自主抑制结束起的眨眼后潜伏期。志愿者根据随机变化时长的声音音调抑制他们的眨眼。在抑制结束时，志愿者撤销抑制并放松。有趣的是，自发的眨眼后反应固定在抑制结束时，就好像发生器从关闭状态恢复一样。眨眼后潜伏期与抑制时长无关，即使抑制时长仅为平均眨眼间隔的一小部分，也会产生与抑制结束时间锁定的眨眼后反应。有趣的是，在抑制后插入自主眨眼会通过延迟自发的眨眼后反应进一步改变眨眼发生器。我们提出，在发生器水平上对自发眨眼的抑制允许进行高效的自主撤销。然而，这种抑制的撤销与运动兴奋密切相关。
