Abstract
BackgroundIn contrast to traditional views that consider smooth pursuit as a relatively automatic process, evidence has been reported for the importance of attention for accurate pursuit performance. However, the exact role that attention might play in the maintenance of pursuit remains unclear.Methodology/Principal FindingsWe analysed the neuronal activity associated with healthy subjects executing smooth pursuit eye movements (SPEM) during concurrent attentive tracking of a moving sound source, which was either in-phase or in antiphase to the executed eye movements. Assuming that attentional resources must be allocated to the moving sound source, the simultaneous execution of SPEM and auditory tracking in diverging directions should result in increased load on common attentional resources. By using an auditory stimulus as a distractor rather then a visual stimulus we guaranteed that cortical activity cannot be caused by conflicts between two simultaneous visual motion stimuli. Our results revealed that the smooth pursuit task with divided attention led to significantly higher activations bilaterally in the posterior parietal cortex and lateral and medial frontal cortex, presumably containing the parietal, frontal and supplementary eye fields respectively.ConclusionsThe additional cortical activation in these areas is apparently due to the process of dividing attention between the execution of SPEM and the covert tracking of the auditory target. On the other hand, even though attention had to be divided the attentional resources did not seem to be exhausted, since the identification of the direction of the auditory target and the quality of SPEM were unaffected by the congruence between visual and auditory motion stimuli. Finally, we found that this form of task-related attention modulated not only the cortical pursuit network in general but also affected modality specific and supramodal attention regions.
Highlights
Human and non-human primates use smooth pursuit eye movements to ensure that the image of an object of interest falls and remains on or near the fovea
Even though attention had to be divided the attentional resources did not seem to be exhausted, since the identification of the direction of the auditory target and the quality of smooth pursuit eye movements (SPEM) were unaffected by the congruence between visual and auditory motion stimuli
Most of this research has concentrated on the close relationship between saccadic eye movements and visual attention [5,6,7,8,9], but comparatively few studies have explored the role of attention in SPEM
Summary
Human and non-human primates use smooth pursuit eye movements to ensure that the image of an object of interest falls and remains on or near the fovea. It has been argued [1] that smooth pursuit eye movements (SPEM) are executed automatically, and do not depend on attention, other authors have found evidence for the importance of attention for accurate pursuit performance [2,3,4]. The exact role that attention might play in the maintenance of pursuit remains unclear, but one possibility is that it facilitates motion processing. The exact role that attention might play in the maintenance of pursuit remains unclear
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