Porciatti V, Bonanni P, Fiorentini A, Guerrini R
Institute of Neurophysiology, Area Ricerca CNR, 1 via Alfieri, 56100 Pisa, Italy.
Nat Neurosci. 2000 Mar;3(3):259-63. doi: 10.1038/72972.
Television and video games may be powerful triggers for visually induced epileptic seizures. To better understand the triggering elements of visual stimuli and cortical mechanisms of hyperexcitability, we examined eleven patients with idiopathic photosensitive epilepsy by recording visually evoked potentials (VEPs) in response to temporally modulated patterns of different contrast. For stimuli of low-medium, but not high, temporal frequency, the contrast dependence of VEP amplitude and latency is remarkably abnormal for luminance contrast (black-white), but not so for chromatic contrast (equiluminant red-green) stimuli. We conclude that cortical mechanisms of contrast gain control for pattern stimuli of relatively low temporal frequency and high luminance contrast are lacking or severely impaired in photosensitive subjects.
电视和电子游戏可能是视觉诱发性癫痫发作的强大诱因。为了更好地理解视觉刺激的触发因素和皮质兴奋性过高的机制，我们通过记录对不同对比度的时间调制图案做出反应的视觉诱发电位（VEP），对11例特发性光敏性癫痫患者进行了检查。对于中低时间频率而非高时间频率的刺激，VEP振幅和潜伏期的对比度依赖性在亮度对比度（黑白）刺激下明显异常，但在颜色对比度（等亮度红绿）刺激下并非如此。我们得出结论，在光敏性受试者中，相对低时间频率和高亮度对比度的图案刺激的对比度增益控制的皮质机制缺乏或严重受损。
