Specific impairment of visual spatial covert attention mechanisms in Parkinson's disease

• Autor(a) principal: Sampaio, Joana
• Data de Publicação: 2011
• Outros Autores: Campos, Elzbieta Bobrowicz, André, Rui, Almeida, Inês, Faria, Pedro, Januário, Cristina, Freire, António, Castelo-Branco, Miguel
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10316/92859; https://doi.org/10.1016/j.neuropsychologia.2010.11.002
• topic: Visual impairment; Covert attention; Visual integration; Parkinson's disease; Visual dorsal stream; Parietal cortex; Inter-hemispheric asymmetries; Spatial processing; Aged; Analysis of Variance; Attention Deficit Disorder with Hyperactivity; Cues; Female; Functional Laterality; Humans; Male; Middle Aged; Neuropsychological Tests; Parkinson Disease; Perceptual Disorders; Photic Stimulation; Psychophysics; Reaction Time; Severity of Illness Index; Space Perception; Statistics as Topic; Visual Perception

Visual deficits in early and high level processing nodes have been documented in Parkinson's disease (PD). Non-motor high level visual integration deficits in PD seem to have a cortical basis independently of a low level retinal contribution. It is however an open question whether sensory and visual attention deficits can be separated in PD. Here, we have explicitly separated visual and attentional disease related patterns of performance, by using bias free staircase procedures measuring psychophysical contrast sensitivity across visual space under covert attention conditions with distinct types of cues (valid, neutral and invalid). This further enabled the analysis of patterns of dorsal-ventral (up-down) and physiological inter-hemispheric asymmetries. We have found that under these carefully controlled covert attention conditions PD subjects show impaired psychophysical performance enhancement by valid attentional cues. Interestingly, PD patients also show paradoxically increased visual homogeneity of spatial performance profiles, suggesting flattening of high level modulation of spatial attention. Finally we have found impaired higher level attentional modulation of contrast sensitivity in the visual periphery, where mechanisms of covert attention are at higher demands. These findings demonstrate a specific loss of attentional mechanisms in PD and a pathological redistribution of spatial mechanisms of covert attention.