Impairments of oculomotor control in a patient with a right temporo-parietal lesion.
Goal-driven control over saccade target selection requires the inhibition of task-irrelevant, stimulus-driven saccades. A widely held assumption is that frontal structures are of critical importance for this function. Here we report the oculomotor capture behaviour of a patient with a right temporo-parietal lesion, which challenges this view. T.H. was asked to search for a target among distractors and to signal its location with a saccade. A task-irrelevant, additional distractor appeared with or without abrupt onset, and it was either similar or dissimilar in its colour to the target. Compared to controls, T.H. showed an elevated level of capture overall. He also showed spatial extinction, which was partially overridden by an abrupt onset distractor. These results support the view that effective oculomotor control depends on an intact network of frontal and posterior brain regions. We argue that stimulus-driven and goal-driven signals are computed at different stages, but are ultimately combined in a common functional salience map.
University of Glasgow, Glasgow, Scotland, UK.
Stephen H
SH
Butler
Iain D
ID
Gilchrist
Casimir J H
CJ
Ludwig
Keith
K
Muir
Monika
M
Harvey