在1997年，日本曾有超过700名儿童因观看某部动画片导致癫痫发作，后来经诊断发现这是一种由于动画片中出现的光刺激引起的光敏性癫痫(photosensitive epilepsy)。
当前，电视视频等已经走进千家万户，因此，检测彩色显示器中能导致癫痫发作的重要视觉参数就显得尤为重要。尽管彩色显示器已经很常见，但很少有人知道色度(chromaticity)和光敏性(photosensitivity)之间的关系，更不用说了解患者大脑和健康人大脑在应对这种光刺激时有何种差别。
在一篇发表于9月25日PLoS ONE的研究报告中，伦敦大学Joydeep Bhattacharya等人做了一项实验——在不停闪烁的组合色彩的下，测试大脑的感光节律(rhythms of photosensitivity)，实验对象包括1例未接受治疗的光敏性癫痫患者，2例健康者对照，6例接受治疗的光敏性癫痫患者。
结果表明，在接受可能引发癫痫的光刺激下，健康人的大脑将出现高度混乱并努力稳定这种不确定性的混乱状态。而癫痫患者在这种刺激下，大脑仍保持一种高度稳定状态。进一步研究发现，大脑的活跃程度可以通过某些色彩组合进行调节。如，红蓝组合的闪烁光刺激比红绿或蓝绿组合光更能使大脑皮质兴奋。（生物谷bioon.com）
生物谷推荐原始出处：
PLoS ONE 4(9): e7173. doi:10.1371/journal.pone.0007173
Investigating Neuromagnetic Brain Responses against Chromatic Flickering Stimuli by Wavelet Entropies
Mayank Bhagat1, Chitresh Bhushan2, Goutam Saha2, Shinsuke Shimjo3,4,5, Katsumi Watanabe5,6,7, Joydeep Bhattacharya8,9*
1 Department of Electrical Engineering, Indian Institute of Technology, Kharagpur, India, 2 Electronics & Electrical Communication Engineering, Indian Institute of Technology, Kharagpur, India, 3 Department of Biology, California Institute of Technology, Pasadena, California, United States of America, 4 NTT Communication Sciences Laboratories, Atsugi, Kanagawa, Japan, 5 Exploratory Research for Advanced Technology (ERATO), Japan Science & Technology Agency, Atsugi, Kanagawa, Japan, 6 Research Center of Advanced Science and Technology, University of Tokyo, Tokyo, Japan, 7 National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki, Japan, 8 Department of Psychology, Goldsmiths College, University of London, London, United Kingdom, 9 Commission for Scientific Visualization, Austrian Academy of Sciences, Vienna, Austria
Background
Photosensitive epilepsy is a type of reflexive epilepsy triggered by various visual stimuli including colourful ones. Despite the ubiquitous presence of colorful displays, brain responses against different colour combinations are not properly studied.
Methodology/Principal Findings
Here, we studied the photosensitivity of the human brain against three types of chromatic flickering stimuli by recording neuromagnetic brain responses (magnetoencephalogram, MEG) from nine adult controls, an unmedicated patient, a medicated patient, and two controls age-matched with patients. Dynamical complexities of MEG signals were investigated by a family of wavelet entropies. Wavelet entropy is a newly proposed measure to characterize large scale brain responses, which quantifies the degree of order/disorder associated with a multi-frequency signal response. In particular, we found that as compared to the unmedicated patient, controls showed significantly larger wavelet entropy values. We also found that Renyi entropy is the most powerful feature for the participant classification. Finally, we also demonstrated the effect of combinational chromatic sensitivity on the underlying order/disorder in MEG signals.
Conclusions/Significance
Our results suggest that when perturbed by potentially epileptic-triggering stimulus, healthy human brain manages to maintain a non-deterministic, possibly nonlinear state, with high degree of disorder, but an epileptic brain represents a highly ordered state which making it prone to hyper-excitation. Further, certain colour combination was found to be more threatening than other combinations.
