在1997年,，日本曾有超過700名兒童因觀看某部動(dòng)畫片導(dǎo)致癲癇發(fā)作，后來經(jīng)診斷發(fā)現(xiàn)這是一種由于動(dòng)畫片中出現(xiàn)的光刺激引起的光敏性癲癇(photosensitive epilepsy),。
當(dāng)前,，電視視頻等已經(jīng)走進(jìn)千家萬戶，因此,，檢測彩色顯示器中能導(dǎo)致癲癇發(fā)作的重要視覺參數(shù)就顯得尤為重要,。盡管彩色顯示器已經(jīng)很常見，但很少有人知道色度(chromaticity)和光敏性(photosensitivity)之間的關(guān)系,，更不用說了解患者大腦和健康人大腦在應(yīng)對(duì)這種光刺激時(shí)有何種差別,。
在一篇發(fā)表于9月25日PLoS ONE的研究報(bào)告中，倫敦大學(xué)Joydeep Bhattacharya等人做了一項(xiàng)實(shí)驗(yàn)——在不停閃爍的組合色彩的下,，測試大腦的感光節(jié)律(rhythms of photosensitivity),，實(shí)驗(yàn)對(duì)象包括1例未接受治療的光敏性癲癇患者，2例健康者對(duì)照,，6例接受治療的光敏性癲癇患者,。
結(jié)果表明,，在接受可能引發(fā)癲癇的光刺激下，健康人的大腦將出現(xiàn)高度混亂并努力穩(wěn)定這種不確定性的混亂狀態(tài),。而癲癇患者在這種刺激下,，大腦仍保持一種高度穩(wěn)定狀態(tài)。進(jìn)一步研究發(fā)現(xiàn),，大腦的活躍程度可以通過某些色彩組合進(jìn)行調(diào)節(jié),。如，紅藍(lán)組合的閃爍光刺激比紅綠或藍(lán)綠組合光更能使大腦皮質(zhì)興奮,。（生物谷bioon.com）
生物谷推薦原始出處：
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.
