Effects of Parkinson’s disease on optic flow perception for heading direction during navigation

Abstract

Visuoperceptual disorders have been identified in individuals with Parkinson’s disease (PD) and may affect the perception of optic flow for heading direction during navigation. Studies in healthy subjects have confirmed that heading direction can be determined by equalizing the optic flow speed (OS) between visual fields. The present study investigated the effects of PD on the use of optic flow for heading direction, walking parameters, and interlimb coordination during navigation, examining the contributions of OS and spatial frequency (dot density). Twelve individuals with PD without dementia, 18 age-matched normal control adults (NC), and 23 young control adults (YC) walked through a virtual hallway at about 0.8 m/s. The hallway was created by random dots on side walls. Three levels of OS (0.8, 1.2, and 1.8 m/s) and dot density (1, 2, and 3 dots/m2) were presented on one wall while on the other wall, OS and dot density were fixed at 0.8 m/s and 3 dots/m2, respectively. Three-dimensional kinematic data were collected, and lateral drift, walking speed, stride frequency and length, and frequency, and phase relations between arms and legs were calculated. A significant linear effect was observed on lateral drift to the wall with lower OS for YC and NC, but not for PD. Compared to YC and NC, PD veered more to the left under OS and dot density conditions. The results suggest that healthy adults perceive optic flow for heading direction. Heading direction in PD may be more affected by the asymmetry of dopamine levels between the hemispheres and by motor lateralization as indexed by handedness.

Visual self-motion cues are impaired in Parkinson’s disease yet over-weighted during visual-vestibular integration

“…Altered veering in response to visual optic flow has been described in PD (Davidsdottir et al, 2008;Lin et al, 2014). However, with graded motor actions (veering) as responses, those studies do not dissociate perceptual from motor or sensorimotor dysfunction.…”

“…PD patients demonstrate altered navigational veering in response to visual self-motion (optic flow) stimuli (Davidsdottir et al, 2008;Lin et al, 2014), as well as reduced activation in visuomotor brain areas (van der Hoorn et al, 2014). While these studies imply visual deficits of self-motion perception, they do not isolate whether or not there is a specific perceptual (vs. sensorimotor) deficit, because veering is a graded motor response.…”

Veering in hemi-Parkinson’s disease: Primacy of visual over motor contributions

“…Age was a significant covariate F (1,17) = 9.92, p = 0.006, η 2 = 0.37. Because we found no significant effect of group whether analyzing left vs. right leg or more-affected vs. less-affected leg, the normalized stride length based on the left leg time series was used in further analyses, as per convention (e.g., Lin et al, 2014; Morris et al, 2005; Young et al, 2010). …”

“…Individuals with PD typically have less stable and more asymmetric gait patterns during locomotion, with shorter stride length on the initially affected body side than on the secondarily affected body side (Lin, Wagenaar et al 2014; Plotnik, Giladi et al 2005; Young, Wagenaar et al 2010). Although no conclusive association has been drawn between motor asymmetry and veering, the difference in stride length between body sides has been offered as an explanation (Guth and Laduke 1994).…”

A Review Ba(OH)2 : Transpor Ionik pada Barium Hidroksida di dalam Air dengan Konsep Termodinamika

“…Kedua gaya itu bekerja dalam arah yang berlawanan dan ion mencapai kecepatan akhir,yaitu kecepatan hanyut (185)(186)(187)(188)(189)(190)(191)(192)(193)(194)(195)(196)(197)(198)(199)(200) ,jika gaya mempercepat Iediimbangi dengan penahan kentalIe' gaya neto menjadi nol (Ie = Ie' ),jika ; s=zeE/f (8)…”