The Neural Mechanisms Underlying Flicker Fusion

每天，世界各地的人们都在闪烁的人工照明条件下工作，或者观察闪烁的电脑、电视显示器或电影画面。有些人比其他人更好地将这些短暂的、静止的图像融合成稳定的运动。考虑到对这种融合的广泛需求，即使是带来功能上的适度提升的进步也将产生非常重大的影响。此外，某些形式的闪烁会导致大脑处于病理活动状态，如上光性癫痫。原因尚不清楚，因为闪光感知背后的基本生理学尚不清楚。虽然闪烁刺激在观看时间中只有一小部分是可见的，但它们看起来是连续和稳定的，因为我们在一种称为闪烁融合的过程中感知地整合了连续的闪光。然而，生理证据表明，闪光频率高于最高可感知的闪光频率仍然会产生皮质和皮质下的视觉反应。因此，视网膜整合引起的闪烁融合不是该现象的唯一解释，大脑视觉系统中随后肯定存在闪烁融合机制。此外，闪烁融合背后的过程可能根本不是时间整合：闪烁融合背后的机制过程是未知的。这种知识上的差距使得在闪烁条件下优化知觉稳定性变得困难。在NSF的支持下，圣约瑟夫医院和医学中心的Stephen Macknik博士希望发现导致闪烁融合的机械过程。这项研究的中心假设是，闪光融合是由闪光刺激本身在侧向抑制网络中产生的瞬时神经反应的抑制性相互作用引起的。通过了解侧抑制的时间动力学，我们将确定在闪烁条件下最大限度地融合闪烁和知觉稳定性的参数。中央机制的重要性将通过一种新发现的名为“时间融合”的错觉来评估。在这种情况下，如果将正确的口罩应用于周围视野，则间隔100ms的两次闪光(通常很容易被视为两次闪光)看起来是一个长闪光。这突显了侧向抑制的重要性，以及除了闪光融合之外还需要解释的必要性。这项研究的结果可能会影响到在荧光灯和/或白炽灯下工作的每一个人，或者使用电视、监视器或任何电影观看设备工作的人。因此，该项目影响到世界各地的整个现代劳动力。这些发现将有助于推动先进技术传播到监视器和照明制造商，以及OSHA等劳动力健康监测组织，从而最大限度地提高观看舒适度，从而提高现代劳动力的效率。

Every day, people worldwide operate under flickering artificial lighting conditions, or observe flickering computer or TV displays or cinematic pictures. Some people fuse these brief, still images into steady movement better than others. Given the widespread need for such fusion, advances leading to even modest gains of function will have a very significant impact. Moreover, some forms of flicker can lead to pathological activity states in the brain, such as photogenic epilepsy. The reasons are unknown, because the fundamental physiology underlying flicker perception is unknown. Although flickering stimuli are visible for only a fraction of the viewing time, they appear as continuous and stable because we perceptually integrate successive flashes in a process called flicker fusion. However, physiological evidence shows that flicker rates above the highest perceived rate of flicker nevertheless generates cortical and subcortical visual responses. Thus flicker fusion caused by integration at the retina cannot be the sole explanation of the phenomenon, and there must be flicker fusion mechanisms later in the visual system of the brain. Moreover, the process underlying flicker fusion may not be temporal integration whatsoever: the mechanistic processes behind flicker fusion are unknown. This gap in knowledge has made it difficult to optimize perceptual stability under flickering conditions. With support from NSF, Dr. Stephen Macknik of St. Joseph's Hospital and Medical Center hopes to discover the mechanistic processes that lead to flicker fusion. The central hypothesis of the study is that flicker fusion is caused by the suppressive interaction of transient neural responses generated by the flickering stimuli themselves, within a lateral inhibition network. By understanding the temporal dynamics of lateral inhibition, we will determine the parameters that maximize flicker fusion and perceptual stability under flickering conditions. The importance of central mechanisms will be assessed with a newly discovered illusion called "Temporal Fusion." In this, two flashes at an interval of 100 ms (typically easily seen as two flashes) appear to be one long flash if the correct masks are applied to the peripheral visual field. This highlights the importance both of lateral inhibition and of the need for explanations beyond flicker fusion.The results of the study potentially affect every person working under fluorescent and/or incandescent artificial lighting, or working with a TV, a monitor, or any cinematic viewing device. Thus the project impacts the entire modern workforce worldwide. These discoveries will serve to drive advances to be disseminated to monitor and lighting manufacturers, as well as to workforce health monitoring organizations such as OSHA, so as to maximize viewing comfort, and thus efficiency in the modern workforce.