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Amanda Douglass, Mark Walterfang, Larry A Abel; Gaze patterns are largely normal but performance is impaired during visual search in frontotemporal dementia. Invest. Ophthalmol. Vis. Sci. 2017;58(8):756.
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© ARVO (1962-2015); The Authors (2016-present)
Behavioural variant frontotemporal dementia (bvFTD) is an insidious progressive disease which affects speech and behaviour. BvFTD patients are known to have difficulty with visual search. This study aimed to explore eye movements during visual search in these patients.
15 bvFTD as well as 19 age and sex matched control participants were recruited to undertake two visual search tasks: a colour visual search, and a conjunction task requiring both colour and orientation to be correctly identified. Each task presented visual search targets in a grid pattern (4x4, 5x5… etc.) with between 16 and 100 items present on the screen. Participants were asked to indicate if the target was present or absent.
In all search tasks bvFTD participants produced more errors. Slope values for reaction time by array size were not significantly different between bvFTD and controls, whilst bvFTD participants consistently displayed a significantly increased intercept value on both colour (W=236, p<0.001), and conjunction (W=296, p<0.001) searches. BvFTD participants, when performing the task correctly, examined more objects for both colour (F(1,219)=11.260, p<0.001), and conjunction searches (F(1,232)=11.800, p<0.001), as well as making more fixations for both colour (F(1,219)=55.479, p<0.001), and conjunction (F(1,232)=30.045, p<0.001). For the conjunction task this was due to an increase at small array sizes, with no significant difference for larger arrays. An effect of array size was also present for string editing, with bvFTD participants displaying greater variability in their scan paths than controls only for smaller arrays.
BvFTD participants displayed grossly normal patterns of eye movements in the visual search task. A small increase is seen in reaction time, but this is due to an increased latency for the task as indicated by the increased reaction time intercept, rather than difficulty processing the task. Differences are primarily seen between the two groups for smaller array sizes where control participants perform optimally. The grossly normal eye movements and impaired performance have potential to differentiate these patients from other diagnostic groups including Alzheimer’s disease, which display abnormal scan paths in these tasks.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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