title: Animal spotting in Alzheimer's disease: an eye tracking study of object categorization.
abstract: We investigated rapid object categorization and, more specifically, the ability to detect a target object within a natural scene in people with mild Alzheimer's disease (AD) using a saccadic choice task. It has been suggested that the anatomical pathway likely used to initiate rapid oculomotor responses in the saccadic choice task could involve the Frontal Eye Field, a structure that is part of the dorsal attentional network, in which connectivity is disrupted in AD. Seventeen patients with mild AD and 23 healthy age-matched controls took part in the study. A group of 24 young healthy observers was included as it has been reported that normal aging affects eye movements. Participants were presented with pairs of colored photographs of natural scenes, one containing an animal (the target) and one containing various objects (distracter), displayed for 1 s left and right of fixation. They were asked to saccade to the scene containing an animal. Neither pathology nor age affected temporal (saccade latencies and durations) and spatial (saccade amplitude) parameters of eye movements. Patients with AD were significantly less accurate than age-matched controls, and older participants were less accurate than young observers. The results are interpreted in terms of noisier sensory information and increased uncertainty in relation to deficits in the magnocellular pathway. The results suggest that, even at a mild stage of the pathology, people exhibit difficulties in selecting relevant objects.
authors.affiliation: Laboratoire de Neurosciences et Pathologies Fonctionnelles, Université Lille-Nord de France, CNRS, France.
authors.forename: Muriel
authors.initials: M
authors.lastname: Boucart
authors.affiliation: Laboratoire de Neurosciences et Pathologies Fonctionnelles, Université Lille-Nord de France, CNRS, France.
authors.forename: Giovanna
authors.initials: G
authors.lastname: Bubbico
authors.affiliation: Laboratoire de Neurosciences et Pathologies Fonctionnelles, Université Lille-Nord de France, CNRS, France.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Szaffarczyk
authors.affiliation: Université Lille Nord de France, EA1046, CHU, Centre mémoire, Lille, France.
authors.forename: Florence
authors.initials: F
authors.lastname: Pasquier
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D000544:Alzheimer Disease / Q000503:physiopathology*; D000704:Analysis of Variance; D000818:Animals; D001288:Attention / Q000502:physiology; D002138:Calibration; D005260:Female; D006801:Humans; D008297:Male; D011930:Reaction Time / Q000502:physiology; D012438:Saccades / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*
keywords: Alzheimer's disease; eye movements; saccade; scene perception