Ronconi Luca, Bellacosa Marotti Rosilari
Center for Mind/Brain Sciences (CIMeC), University of Trento, Rovereto, TN, Italy; Scientific Institute IRCCS "E. Medea", Bosisio Parini, Lecco, Italy.
International School for Advanced Studies (SISSA), Trieste, Italy.
Conscious Cogn. 2017 Sep;54:36-46. doi: 10.1016/j.concog.2017.04.020. Epub 2017 May 11.
Visual crowding is among the factors that most hamper conscious object perception. However, we currently ignore the neural states that predispose to an accurate perception within different crowding regimes. Here, we performed single-trial analyses of the electroencephalographical (EEG) oscillations, evaluating the prestimulus power and phase differences between correct and incorrect discrimination during a letter-crowding task, where irrelevant letters were placed nearby (strong crowding) or far (mid crowding) relative to the target. Results show that prestimulus alpha (8-12Hz) power was related to target discrimination in the mid, but not in the strong, crowding condition. Importantly, accurate discrimination in the strong crowding condition was predicted by the phase of alpha and by the power of beta (13-20Hz) oscillations. These evidence suggest that both periodic visual sampling mechanisms, reflected in the alpha phase, and network predisposition to extract local information, reflected in the beta power, predispose to object discrimination in a crowded scene.
视觉拥挤是最妨碍有意识物体感知的因素之一。然而，我们目前忽略了在不同拥挤状态下有利于准确感知的神经状态。在这里，我们对脑电图（EEG）振荡进行了单试次分析，评估了在字母拥挤任务中正确和错误辨别之间的刺激前功率和相位差异，在该任务中，无关字母相对于目标放置在附近（强拥挤）或远处（中等拥挤）。结果表明，刺激前α波（8-12Hz）功率与中等拥挤条件下的目标辨别有关，但与强拥挤条件下无关。重要的是，强拥挤条件下的准确辨别可由α波相位和β波（13-20Hz）振荡功率预测。这些证据表明，α波相位反映的周期性视觉采样机制和β波功率反映的提取局部信息的网络倾向，都有利于在拥挤场景中进行物体辨别。
