Functional correlates of optic flow motion processing in Parkinson's disease.

Deepti Putcha,David C Somers,Alice Cronin-Golomb,Chantal E Stern,Robert S Ross,Maya L Rosen,Daniel J Norton

doi:10.3389/fnint.2014.00057

Abstract

The visual input created by the relative motion between an individual and the environment, also called optic flow, influences the sense of self-motion, postural orientation, veering of gait, and visuospatial cognition. An optic flow network comprising visual motion areas V6, V3A, and MT+, as well as visuo-vestibular areas including posterior insula vestibular cortex (PIVC) and cingulate sulcus visual area (CSv), has been described as uniquely selective for parsing egomotion depth cues in humans. Individuals with Parkinson’s disease (PD) have known behavioral deficits in optic flow perception and visuospatial cognition compared to age- and education-matched control adults (MC). The present study used functional magnetic resonance imaging (fMRI) to investigate neural correlates related to impaired optic flow perception in PD. We conducted fMRI on 40 non-demented participants (23 PD and 17 MC) during passive viewing of simulated optic flow motion and random motion. We hypothesized that compared to the MC group, PD participants would show abnormal neural activity in regions comprising this optic flow network. MC participants showed robust activation across all regions in the optic flow network, consistent with studies in young adults, suggesting intact optic flow perception at the neural level in healthy aging. PD participants showed diminished activity compared to MC particularly within visual motion area MT+ and the visuo-vestibular region CSv. Further, activation in visuo-vestibular region CSv was associated with disease severity. These findings suggest that behavioral reports of impaired optic flow perception and visuospatial performance may be a result of impaired neural processing within visual motion and visuo-vestibular regions in PD.

Highlights

Parkinson’s disease (PD) IS ASSOCIATED WITH REDUCED ACTIVITY IN cingulate sulcus visual area (CSv) AND MT+ DURING OPTIC FLOW PERCEPTION ROI analysis focused on five cortical regions previously identified as key nodes of the optic flow network in healthy young www.frontiersin.org adults (Cardin and Smith, 2010)
We examined the functional neural correlates of optic flow processing in PD in light of existing behavioral evidence suggesting that disruption in optic flow processing may underlie visuospatial deficits observed behaviorally (Davidsdottir et al, 2008; Young et al, 2010)
We found that individuals with PD showed changes in activation patterns compared to the healthy aging group within the optic flow network overall, and demonstrated less activity within visual motion area MT+ and the visuo-vestibular region CSv in response to perception of optic flow

Summary

Introduction

Parkinson’s disease (PD) is a progressive neurodegenerative disorder characterized by tremor, rigidity, postural instability, bradykinesia, and gait disturbance (Young et al, 2010), as well as non-motor dysfunction including perceptual deficits (Davidsdottir et al, 2008; Armstrong, 2011) and visuospatial impairment (Amick et al, 2006; Stepkina et al, 2010; Poletti et al, 2012). Some of the visuospatial impairments seen in PD patients may be related to changes in how egocentric visual motion, or optic flow, information is processed. Optic flow perception has been linked to disturbances in gait (Davidsdottir et al, 2008), heading direction (Chou et al, 2009) and navigational abilities (Young et al, 2010) in PD, and is a critical aspect of visuospatial cognition (Warren et al, 2001). PD pathology impacts optic flow perception at the behavioral level, characterized by veering and navigational difficulty (Davidsdottir et al, 2008; Young et al, 2010), and structurally, as observed in atrophy of regions of the parietal lobe and parietooccipital sulcus (Tinaz et al, 2011)

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Conclusion