Out of Sight, Out of Mind? Stuart S, Galna B, Lord S, and Rochester L Institute of Neuroscience/Newcastle University Institute of Ageing, Newcastle University http://research.ncl.ac.uk/hmst |
@HMSTeam |
Introduction
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Methods
Visual exploration of the environment through appropriate eye-movements is vital for safe and effective walking [1]. Purposeful and non-purposeful eye movements are produced and prevented by cognition, respectively. Cognitive impairment is common in Parkinson’s disease (PD) and likely affects visual exploration, and so contributes to walking problems and falls risk. This study describes preliminary analysis of eye-movements during walking in PD in response to environmental and attentional demand, and the association between eye-movements and cognition.
A Dikablis mobile eye-tracker (Fig 1 and 2) was used to measure saccadic (fast) eye movement frequency (number of saccades per second) during gait in 30 subjects with PD and 30 healthy control older adults (≥50 years) (HC). Clinical, cognitive and visual assessments were also performed using a range of standardised tests. Participants then walked under varied environmental conditions (straight, through a door and turning left or right) and attentional demand (single and dual-task) (Fig 3). A saccade was classed as an eye movement with a velocity threshold of ≥240 degrees/second (~5° amplitude) [2,3]. Cognitive and visual outcomes were correlated with saccade frequency, a proxy for purposeful visual attention. Straight walk
Straight walk through a door
40° turn
40° turn starting 10° off centre
2.5m
0.8m
Fig 3 Walking Conditions
Results 1.4
Saccade Frequency (saccades/sec)
• PD participants had significantly impaired cognition and vision compared to HC (Table 1) • PD participants made fewer eye-movements (p=.009, Table 2) than HC during all of the walks, particularly during a dual task (Fig 4) suggesting they explore the environment less • Eye-movement significantly increased with environmental complexity (p
