Parkinson's patients can rely on perspective cues to perceive 3D space.
3D perception, which is necessary for an optimal navigation in our environment, relies on 2 complementary kinds of cues; binocular cues allowing precise depth localization near the point of visual interest and monocular ones that are necessary for correct global perception of visual space. Recent studies described deficient binocular 3D vision in PD patients; here we tested 3D vision in PD patients when based on monocular cues (m3D). Sixteen PD patients and 16 controls had to categorize visual stimuli as perceived in 2D (flat) or 3D (with depth). Both performance and response times were measured. EEGs were recorded to extract Visual Evoked Potentials. Effects of PD were tested by comparing psychometric and electrophysiological data obtained in controls and PD patients evaluated without dopaminergic treatment. Effects of Levodopa were tested by comparing data in PD patients with and without dopaminergic treatment. We didn't find statistical differences between PD patients and controls' performance. Severity of PD (UPDRS III) in OFF condition is positively correlated with P1 amplitudes and latencies for both 2D and m3D stimuli. Levodopa administration didn't modify either PD patients' performances although it increases principal visual components latencies for both 2D and m3D stimuli. Unlike binocular 3D vision, monocular 3D vision does not seem to get affected by PD. However given the correlation between severity of PD and VEPs' modifications, alteration of visual cortical processing might have nonetheless begun. PD patients reporting trouble in perceiving space must rely more on m3D cues present in the environment.
CerCo, Centre de Recherche Cerveau et Cognition, Université de Toulouse UPS, CNRS-UMR 5549, Toulouse, France. Electronic address: alexandra.severac@cnrs.fr.
Alexandra
A
Séverac Cauquil
INSERM UMR1214, Imagerie cérébrale et handicaps neurologiques, Toulouse, France; Department of Neurology, University Hospital of Toulouse, Toulouse, France. Electronic address: ory.f@chu-toulouse.fr.
Fabienne
F
Ory-Magne
CerCo, Centre de Recherche Cerveau et Cognition, Université de Toulouse UPS, CNRS-UMR 5549, Toulouse, France. Electronic address: conquet.s@chu-toulouse.fr.
Vincent
V
Jardiné
Clinical Investigation Center, University Hospital of Toulouse, Toulouse, France. Electronic address: monique.galitzky@inserm.fr.
Monique
M
Galitzky
CerCo, Centre de Recherche Cerveau et Cognition, Université de Toulouse UPS, CNRS-UMR 5549, Toulouse, France. Electronic address: maxime.rosito@cnrs.fr.
Maxime
M
Rosito
INSERM UMR1214, Imagerie cérébrale et handicaps neurologiques, Toulouse, France; Department of Neurology, University Hospital of Toulouse, Toulouse, France; Department of Clinical Pharmacology, University Hospital of Toulouse, Toulouse, France. Electronic address: christine.brefel-courbon@univ-tlse3.fr.
Christine
C
Brefel-Courbon
CerCo, Centre de Recherche Cerveau et Cognition, Université de Toulouse UPS, CNRS-UMR 5549, Toulouse, France. Electronic address: simona.celebrini@cnrs.fr.
Simona
S
Celebrini
D000368:Aged; D000369:Aged, 80 and over; D003463:Cues; D003867:Depth Perception / Q000502:physiology*; D005074:Evoked Potentials, Visual; D005260:Female; D006801:Humans; D007980:Levodopa; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000150:complications / Q000503:physiopathology*; D020734:Parkinsonian Disorders / Q000503:physiopathology; D010775:Photic Stimulation; D015348:Vision, Binocular / Q000502:physiology; D015349:Vision, Monocular / Q000502:physiology; D014793:Visual Cortex / Q000502:physiology; D014796:Visual Perception / Q000502:physiology*
D007980:Levodopa
3D perception; Parkinson disease; Psychophysics; VEP; Vision