Please use this identifier to cite or link to this item: http://hdl.handle.net/10316/92859
Title: Specific impairment of visual spatial covert attention mechanisms in Parkinson's disease
Authors: Sampaio, Joana
Campos, Elzbieta Bobrowicz 
André, Rui 
Almeida, Inês
Faria, Pedro
Januário, Cristina 
Freire, António
Castelo-Branco, Miguel 
Keywords: Visual impairment; Covert attention; Visual integration; Parkinson's disease; Visual dorsal stream; Parietal cortex; Inter-hemispheric asymmetries; Spatial processing
Issue Date: Jan-2011
Publisher: Elsevier
Project: PTDC/SAU/NEU-68483-2006 
PTDC/PSI-67381-2006 
PIC/IC-82986-2007 
Serial title, monograph or event: Neuropsychologia
Volume: 49
Issue: 1
Abstract: 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.
URI: http://hdl.handle.net/10316/92859
ISSN: 00283932
DOI: 10.1016/j.neuropsychologia.2010.11.002
Rights: openAccess
Appears in Collections:FMUC Medicina - Artigos em Revistas Internacionais

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