Article

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 dorsal­ventral (up­down) 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.

Langue : ANGLAIS