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Multisensory interactions in saccade target selection: curved saccade trajectories
Melanie C Doyle1, Robin Walker
1Department of Psychology, Royal Holloway, University of London, Egham, Surrey TW20 0EX, UK. m.doyle@rhul.ac.uk
Abstract:
In a series of experiments, we examined the change in saccade trajectories observed when distractors are presented at non-target locations. The primary aim of the experiments was to examine multisensory interaction effects between the visual, auditory and somatosensory modalities in saccade generation. In each experiment observers made saccades to visual targets above and below fixation in the presence of visual, auditory or tactile stimuli to the left or right of fixation. In experiment 1 distractor location indicated which of two stimuli was the target for the saccade. Saccade trajectories showed strong leftward curvature following right-side distractors and showed rightward curvature following left-side distractors. The largest effects on trajectories were observed for visual distractors, but significant curvature was observed with auditory and somatosensory distractors. In experiment 2 saccades were made following the onset of a visual target (reflexive) or following presentation of an arrow at fixation (voluntary), and task-irrelevant crossmodal distractors were presented simultaneously with target onset. Both voluntary and reflexive saccades were found to curve away from task-irrelevant visual distractors, but auditory and somatosensory distractors did not modulate saccade trajectories. In experiment 3 task-irrelevant distractors preceded the onset of the target by 100 ms. Reflexive saccades were found to curve away from visual, auditory and somatosensory distractors, but voluntary saccades curved away from visual distractors only. The modulation of saccade trajectories by distractors from different modalities is interpreted in terms of inhibitory processes operating in neural structures involved in saccade generation. Our findings suggest that visual, auditory and somatosensory distractors can all modulate saccade trajectories. Such effects could be related to the inhibition of populations of neurons, in a common motor map, for the selection of a saccade target.
Insights
Visual, auditory, and somatosensory distractors can alter eye movement (saccade) paths. These findings suggest crossmodal interactions influence how the brain selects targets for saccades.
Area of Science:
- Neuroscience
- Cognitive Psychology
- Oculomotor Research
Background:
- Saccade generation involves complex neural processes.
- Multisensory integration plays a role in sensorimotor control.
- Distractor stimuli can influence motor responses.
Purpose of the Study:
- To investigate how visual, auditory, and somatosensory distractors affect saccade trajectories.
- To examine multisensory interactions during saccade generation.
- To understand the neural mechanisms underlying distractor effects on eye movements.
Main Methods:
- Participants made saccades to visual targets under various distractor conditions (visual, auditory, somatosensory).
- Distractor stimuli were presented at non-target locations, sometimes indicating the target.
- Saccade trajectories were analyzed for curvature and modulation by distractors.
Main Results:
- Distractors, particularly visual ones, induced significant curvature in saccade trajectories.
- Auditory and somatosensory distractors also modulated saccade paths, especially when preceding target onset.
- Reflexive saccades were more susceptible to crossmodal distractor effects than voluntary saccades.
Conclusions:
- Multisensory distractors can modulate saccade trajectories, indicating crossmodal influences on oculomotor control.
- These effects may arise from inhibitory processes within a common neural map for target selection.
- The findings provide insights into the neural basis of sensorimotor integration and attention.