Impact of optic flow perception and egocentric coordinates on veering in Parkinson's disease

Department of Psychology, Boston University, Boston, MA 02215, USA.
Brain (Impact Factor: 9.2). 12/2008; 131(Pt 11):2882-93. DOI: 10.1093/brain/awn237
Source: PubMed


Spatial navigation is a complex process requiring integration of visuoperceptual information. The present study examined how visuospatial function relates to navigational veering in Parkinson's disease, a movement disorder in which visuospatial cognition is affected by the degeneration of the basal ganglia and resulting dysfunction of the parietal lobes. We hypothesized that patients whose initial motor symptoms start on the left versus right side of the body (LPD, predominant right-hemisphere dysfunction; RPD, predominant left-hemisphere dysfunction) would display distinct patterns of navigational veering associated with the groups' dissimilar visuospatial profiles. Of particular interest was to examine the association of navigational veering (lateral deviation along the medio-lateral axis) with perception of egocentric coordinates and of radial optic flow patterns, both of which are mediated by the parietal lobes. Thirty-one non-demented Parkinson's disease patients (16 LPD, 15 RPD) and 18 healthy control (HC) adults received visuospatial tests, of whom 23 Parkinson's disease patients and 17 HC also underwent veering assessment. The participants were examined on three visual-feedback navigation conditions: none (eyes closed), natural, and optic flow supplied by a virtual-reality headset. All groups veered to the left when walking with eyes closed, women with Parkinson's disease more so than the other participants. On the navigation assessments with visual feedback, only LPD patients deviated right of centre. On tests of visuospatial function, the perceived midline was shifted rightward in LPD (men and women), increasingly so with the addition of visual input. In contrast, men with RPD showed leftward deviation. RPD patients and HC perceived optic flow in the left hemifield as faster than in the right hemifield, with a trend for the opposite pattern for LPD. Navigational veering in LPD was associated with deviation of the perceived egocentric midline and not with perception of optic flow speed asymmetries, and in RPD it was also associated with visual dependence, though in fact LPD subjects were more visually dependent than those with RPD. Our results indicate that (i) parietal-mediated perception of visual space is affected in Parkinson's disease, with both side of motor symptom onset and gender affecting spatial performance, and (ii) visual input affects veering.

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Available from: Alice Cronin-Golomb
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    • "The use of low - level cues as we describe here is potentially important because reduced stimulus strength has been shown to interact with sensory and perceptual deficits in PD and normal aging , impairing cognition ( e . g . , Clay et al . , 2009 ; Cronin - Golomb , Gilmore , Neargarder , Morrison , & Laudate , 2007 ; Davidsdottir et al . , 2008 ) . A positive converse of this relation is that visually based interventions may enhance cognitive performance . For example , we have shown that letter identification in PD and healthy older adults can be significantly improved by enhancement of stimulus contrast ( Amick et al . , 2003 ; Cronin - Golomb et al . , 2007 ) , and that the"
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    ABSTRACT: Parkinson's disease (PD) and normal aging have been associated with changes in visual perception, including reliance on external cues to guide behavior. This raises the question of the extent to which these groups use visual cues when disambiguating information. Twenty-seven individuals with PD, 23 normal control adults (NC), and 20 younger adults (YA) were presented a Necker cube in which one face was highlighted by thickening the lines defining the face. The hypothesis was that the visual cues would help PD and NC to exert better control over bistable perception. There were three conditions, including passive viewing and two volitional-control conditions (hold one percept in front; and switch: speed up the alternation between the two). In the Hold condition, the cue was either consistent or inconsistent with task instructions. Mean dominance durations (time spent on each percept) under passive viewing were comparable in PD and NC, and shorter in YA. PD and YA increased dominance durations in the Hold cue-consistent condition relative to NC, meaning that appropriate cues helped PD but not NC hold one perceptual interpretation. By contrast, in the Switch condition, NC and YA decreased dominance durations relative to PD, meaning that the use of cues helped NC but not PD in expediting the switch between percepts. Provision of low-level cues has effects on volitional control in PD that are different from in normal aging, and only under task-specific conditions does the use of such cues facilitate the resolution of perceptual ambiguity. (JINS, 2015, 21, 1-10).
    Full-text · Article · Mar 2015 · Journal of the International Neuropsychological Society
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    • "Several studies have found reduced contrast sensitivity in PD (e.g., Amick, Cronin-Golomb, & Gilmore, 2003; Kupersmith, Shakin, Siegel, & Lieberman, 1982; Pieri, Diederich, Raman, & Goetz, 2000), with some suggesting a generalized loss of contrast sensitivity across spatial frequencies (Price, Feldman, Adelberg, & Kayne, 1992), and others indicating a shift in the contrast sensitivity function resulting from changes at specific spatial frequencies (Bodis-Wollner et al., 1987). With respect to LPD-specific biases, Davidsdottir et al. (2008) found no evidence for such. Whether LPD may view objects in the left hemifield to be lower in contrast than those in the right hemifield, using some sort of contrast-matching procedure (Georgeson & Sullivan, 1975) is as yet unknown. "
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    ABSTRACT: Individuals with Parkinson's disease (PD) with symptom onset on the left side of the body (LPD) show mild type of left-sided visuospatial neglect, whereas those with right-onset (RPD) generally do not. The functional mechanisms underlying these observations are unknown. Two hypotheses are that the representation of left-space in LPD is either compressed or reduced in salience. We tested these hypotheses psychophysically. Participants were 31 non-demented adults with PD (15 LPD, 16 RPD) and 17 normal control adults (NC). The spatial compression hypothesis was tested by showing two sinusoidal gratings, side by side. One grating's spatial frequency (SF) was varied across trials, following a staircase procedure, whereas the comparison grating was held at a constant SF. While fixating on a central target, participants estimated the point at which they perceived the two gratings to be equal in SF. The reduced salience hypothesis was tested in a similar way, but by manipulating the contrast of the test grating rather than its SF. There were no significant differences between groups in the degree of bias across hemifields for SF discrimination or for contrast discrimination. Results did not support either the spatial compression hypothesis or the reduced salience hypothesis. Instead, they suggest that at this perceptual level, LPD do not have a systematically biased way of representing space in the left hemifield that differs from healthy individuals, nor do they perceive stimuli on the left as less salient than stimuli on the right. Neglect-like syndrome in LPD instead presumably arises from dysfunction of higher-order attention. Copyright © 2014. Published by Elsevier Ltd.
    Full-text · Article · Dec 2014 · Vision Research
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    • "In fact, men with PD had less error compared to women with PD (PD males: mean 2.15, SD 0.81; PD females: mean 2.81, SD 1.47). Previous work investigating differences in optic flow processing in relation to gait in PD has documented a similar pattern of data, where men with PD perform better than women with PD in a planar motion perception task, whereas HC women outperformed HC men (Davidsdottir et al. 2008). Therefore, this allows us to be quite confident that our results are an effect of PD rather than gender. "
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    ABSTRACT: Although dopaminergic replacement therapy is believed to improve sensory processing in PD, while delayed perceptual speed is thought to be caused by a predominantly cholinergic deficit, it is unclear whether sensory-perceptual deficits are a result of corrupt sensory processing, or a delay in updating perceived feedback during movement. The current study aimed to examine these two hypotheses by manipulating visual flow speed and dopaminergic medication to examine which influenced distance estimation in PD. Fourteen PD and sixteen HC participants were instructed to estimate the distance of a remembered target by walking to the position the target formerly occupied. This task was completed in virtual reality in order to manipulate the visual flow (VF) speed in real time. Three conditions were carried out: (1) BASELINE: VF speed was equal to participants’ real-time movement speed; (2) SLOW: VF speed was reduced by 50 %; (2) FAST: VF speed was increased by 30 %. Individuals with PD performed the experiment in their ON and OFF state. PD demonstrated significantly greater judgement error during BASELINE and FAST conditions compared to HC, although PD did not improve their judgement error during the SLOW condition. Additionally, PD had greater variable error during baseline compared to HC; however, during the SLOW conditions, PD had significantly less variable error compared to baseline and similar variable error to HC participants. Overall, dopaminergic medication did not significantly influence judgement error. Therefore, these results suggest that corrupt processing of sensory information is the main contributor to sensory-perceptual deficits during movement in PD rather than delayed updating of sensory feedback.
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