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The pathophysiology of visual hallucinations in Parkinson's disease has yet to be characterized. Although stimulus-driven ("bottom-up") processes are known to be impaired, the role of "top-down" processes remains to be determined. Distinguishing between conscious and non-conscious detections (i.e. access to consciousness) may be a valuable way of monitoring(More)
The study investigated the mediolateral control of upright stance in 16 healthy, young adults. The model analyzed the body weight distribution and center of pressure location mechanisms under three stance width conditions (feet close, under standard condition, and apart). Our first objective was to discuss some methodological requirements to investigate the(More)
Studies of scene perception have shown that the visual system is particularly sensitive to global properties such as the overall layout of a scene. Such global properties cannot be computed locally, but rather require relational analysis over multiple regions. To what extent is observers' perception of scenes impaired in the far periphery? We examined the(More)
Elderly adults sway more than young adults. Based on the literature, the authors expected the mediolateral ankle postural control mechanism to be affected before age 60 years. Twelve healthy young adults (24.21 ± 2.50 years) and 12 middle-aged adults (51.13 ± 6.09 years) participated in the study. To challenge mediolateral stance, the conditions modified(More)
Medialateral postural control mechanisms (bodyweight distribution and center of pressure location) have been studied in static conditions. Our objective was to determine how these mechanisms are adjusted to perform voluntary movements, in our case 80° lateral gaze shifts at 0.125 Hz and 0.25 Hz. In healthy, young adults, we expected body marker (neck, lower(More)
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(More)
We assessed the effects of donepezil, a drug that stimulates cholinergic transmission, and scopolamine, an antagonist of cholinergic transmission, on contrast sensitivity. 30 young male participants were tested under three treatment conditions: placebo, donepezil, and scopolamine in a random order. Pairs of photographs varying in contrast were displayed(More)
Studies in normally sighted people suggest that scene recognition is based on global physical properties and can be accomplished by the low resolution of peripheral vision. We examine the contribution of peripheral and central vision in scene gist recognition in patients with central vision loss and age-matched controls. Twenty-one patients with neovascular(More)
PURPOSE For normally sighted people, there is a general consensus that objects that appear in a congruent context (e.g., a hair dryer in a bathroom) are processed more accurately and/or more quickly than objects in an incongruent context (e.g., a hair dryer in a corn field). We investigated whether people with AMD, who have impairments in recognizing(More)
PURPOSE We investigated the visuomotor behavior of people with reduced peripheral field due to glaucoma while they accomplished natural actions. METHODS Twelve participants with glaucoma and 13 normally sighted controls were included. Participants were asked to accomplish a familiar sandwich-making task and a less familiar model-building task with a(More)