title: Residual perception of biological motion in cortical blindness.
abstract: 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.
authors.affiliation: Eye and Brain Mapping Laboratory (iBMLab), Department of Psychology, University of Fribourg, Faucigny 2, 1700 Fribourg, Switzerland. Electronic address: nicolas.ruffieux@unifr.ch.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Ruffieux
authors.affiliation: Eye and Brain Mapping Laboratory (iBMLab), Department of Psychology, University of Fribourg, Faucigny 2, 1700 Fribourg, Switzerland.
authors.forename: Meike
authors.initials: M
authors.lastname: Ramon
authors.affiliation: Eye and Brain Mapping Laboratory (iBMLab), Department of Psychology, University of Fribourg, Faucigny 2, 1700 Fribourg, Switzerland.
authors.forename: Junpeng
authors.initials: J
authors.lastname: Lao
authors.affiliation: Unit of Neuropsychology and Aphasiology, Fribourg Hospital, CP, 1708 Fribourg, Switzerland.
authors.forename: Françoise
authors.initials: F
authors.lastname: Colombo
authors.affiliation: Eye and Brain Mapping Laboratory (iBMLab), Department of Psychology, University of Fribourg, Faucigny 2, 1700 Fribourg, Switzerland.
authors.forename: Lisa
authors.initials: L
authors.lastname: Stacchi
authors.affiliation: Jules-Gonin Eye Hospital, University of Lausanne, Avenue de France 15, 1004 Lausanne, Switzerland.
authors.forename: François-Xavier
authors.initials: FX
authors.lastname: Borruat
authors.affiliation: Unit of Neuropsychology and Aphasiology, Fribourg Hospital, CP, 1708 Fribourg, Switzerland; Laboratory for Cognitive and Neurological Sciences, Department of Medicine, University of Fribourg, Ch. du Musée 5, 1700 Fribourg, Switzerland.
authors.forename: Ettore
authors.initials: E
authors.lastname: Accolla
authors.affiliation: Unit of Neuropsychology and Aphasiology, Fribourg Hospital, CP, 1708 Fribourg, Switzerland; Laboratory for Cognitive and Neurological Sciences, Department of Medicine, University of Fribourg, Ch. du Musée 5, 1700 Fribourg, Switzerland.
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Annoni
authors.affiliation: Eye and Brain Mapping Laboratory (iBMLab), Department of Psychology, University of Fribourg, Faucigny 2, 1700 Fribourg, Switzerland. Electronic address: roberto.caldara@unifr.ch.
authors.forename: Roberto
authors.initials: R
authors.lastname: Caldara
mesh_terms: D000328:Adult; D019575:Blindness, Cortical / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology*; D002755:Choice Behavior / Q000502:physiology; D003342:Corpus Striatum / Q000000981:diagnostic imaging / Q000503:physiopathology*; D004192:Discrimination, Psychological / Q000502:physiology; D053483:Eye Movement Measurements; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009039:Motion Perception / Q000502:physiology*; D009203:Myocardial Infarction / Q000150:complications / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000523:psychology; D009483:Neuropsychological Tests; D021641:Recognition, Psychology / Q000502:physiology; D014741:Video Recording; D055815:Young Adult
keywords: Biological motion; Cortical blindness; Eye tracking; Residual visual ability; Striate damage; Task dependency