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Abstract:
Hemispatial neglect affects the ability to respond and
programme saccades to targets on the contralesional side of space.
We investigated if these two features of neglect behaviour recover
at the same rate. Patient AF, who displayed strong hemispatial
neglect one month post right thalamic stroke (BIT score: 68/146)
had recovered substantially two months later (BIT: 136/146). Along
with twelve age-matched healthy controls he completed a visual
search task. In Condition 1 the target was presented without
distractors. In the other conditions, displays contained three
distractors that were changed across conditions to manipulate
target similarity and thus task difficulty. Saccadic performance
(direction and latencies of first saccades) and manual reaction
times were analysed. In Condition 1, like the controls, AF was
unimpaired in the execution of automatic saccades even when they
had to be directed into the neglected field. In contrast, a
considerable left/right difference was present for all other
conditions irrespective of task difficulty. Although recovered from
neglect when assessed with the BIT, which includes a number of
visual search tasks, AF still exhibited highly abnormal first
saccades in search. Measurements of saccades in search are very
sensitive to any remaining spatial impairments even when a residual
impairment is not detected by paper and pencil search
methods.
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