Ruffieux Nicolas, Ramon Meike, Lao Junpeng, Colombo Françoise, Stacchi Lisa, Borruat François-Xavier, Accolla Ettore, Annoni Jean-Marie, Caldara Roberto
Eye and Brain Mapping Laboratory (iBMLab), Department of Psychology, University of Fribourg, Faucigny 2, 1700 Fribourg, Switzerland.
Eye and Brain Mapping Laboratory (iBMLab), Department of Psychology, University of Fribourg, Faucigny 2, 1700 Fribourg, Switzerland.
Neuropsychologia. 2016 Dec;93(Pt A):301-311. doi: 10.1016/j.neuropsychologia.2016.11.009. Epub 2016 Nov 13.
From birth, the human visual system shows a remarkable sensitivity for perceiving biological motion. This visual ability relies on a distributed network of brain regions and can be preserved even after damage of high-level ventral visual areas. However, it remains unknown whether this critical biological skill can withstand the loss of vision following bilateral striate damage. To address this question, we tested the categorization of human and animal biological motion in BC, a rare case of cortical blindness after anoxia-induced bilateral striate damage. The severity of his impairment, encompassing various aspects of vision (i.e., color, shape, face, and object recognition) and causing blind-like behavior, contrasts with a residual ability to process motion. We presented BC with static or dynamic point-light displays (PLDs) of human or animal walkers. These stimuli were presented either individually, or in pairs in two alternative forced choice (2AFC) tasks. When confronted with individual PLDs, the patient was unable to categorize the stimuli, irrespective of whether they were static or dynamic. In the 2AFC task, BC exhibited appropriate eye movements towards diagnostic information, but performed at chance level with static PLDs, in stark contrast to his ability to efficiently categorize dynamic biological agents. This striking ability to categorize biological motion provided top-down information is important for at least two reasons. Firstly, it emphasizes the importance of assessing patients' (visual) abilities across a range of task constraints, which can reveal potential residual abilities that may in turn represent a key feature for patient rehabilitation. Finally, our findings reinforce the view that the neural network processing biological motion can efficiently operate despite severely impaired low-level vision, positing our natural predisposition for processing dynamicity in biological agents as a robust feature of human vision.
从出生起，人类视觉系统对感知生物运动就表现出非凡的敏感性。这种视觉能力依赖于大脑区域的分布式网络，即使在高级腹侧视觉区域受损后也能保留。然而，这种关键的生物技能能否经受住双侧纹状损伤后视力丧失的影响仍不清楚。为了解决这个问题，我们对BC进行了测试，他是缺氧引起双侧纹状损伤后导致皮质盲的罕见病例，我们测试了他对人类和动物生物运动的分类能力。他的损伤严重程度涉及视觉的各个方面（即颜色、形状、面部和物体识别），并导致类似失明的行为，这与他处理运动的残余能力形成对比。我们向BC展示了人类或动物行走者的静态或动态点光显示（PLD）。这些刺激以单独或成对的形式出现在两个二选一强制选择（2AFC）任务中。当面对单个PLD时，患者无法对刺激进行分类，无论它们是静态的还是动态的。在2AFC任务中，BC对诊断信息表现出适当的眼球运动，但在静态PLD任务中表现为随机水平，这与他有效分类动态生物刺激的能力形成鲜明对比。这种对生物运动进行分类的惊人能力所提供的自上而下的信息至少有两个重要原因。首先，它强调了在一系列任务限制下评估患者（视觉）能力的重要性，这可以揭示潜在的残余能力，而这些能力反过来可能代表患者康复的关键特征。最后，我们的研究结果强化了这样一种观点，即尽管低水平视力严重受损，但处理生物运动的神经网络仍能有效运作，这表明我们处理生物动态的自然倾向是人类视觉的一个强大特征。
