Abstract
The human brain is lateralised to the right for visuospatial attention, particularly when reorienting attention to unexpected stimuli. However, the developmental characteristics of lateralisation remain unclear. To address this question, we devised a saccade task applicable for both adults and children. To assess the utility of this system, we investigated the correlation between line bisection test performance and the saccade task for 54 healthy adult volunteers. Participants followed a visual target that jumped 10 times, alternating between two fixed positions across the midline with a constant pace. In both the rightward and leftward directions, saccadic reaction time (RT) to the target jump decreased and reached a plateau from the first to the tenth jumps. Furthermore, we obtained the time required for reorienting in the contralateral hemisphere using the corrected value of the first RT. We found that longer corrected RTs in the rightward saccade were associated with greater deviation to the left in the line bisection task. This correlation was not observed for leftward saccades. Thus, corrected RTs in rightward saccades reflected the strength of individual hemispheric lateralisation. In conclusion, the rightward saccade task provides a suitable marker for lateralised visuospatial attention, and for investigating the development of lateralisation.
Highlights
Right hemispheric lateralisation in visuospatial attention has long been studied in both pathological and healthy conditions
Using a novel square wave saccade task, we investigated whether measuring saccades could detect lateralised visuospatial attention in neurologically intact adults
We found that subsequent saccades showed shorter reaction time (RT) and greater pupil dilation than the first saccade
Summary
Right hemispheric lateralisation in visuospatial attention has long been studied in both pathological and healthy conditions. To investigate the lateralisation of visuospatial attention, several studies have examined asymmetry in response times (RTs) of reflexive saccades among healthy adults. In these studies, subjects made repetitive saccades to a stimulus that appears randomly at either of two fixed positions in the right and left visual fields. Through the repetition of trials, subjects may learn the pattern of target presentation This learning and practice effect may lead subjects to expect the target to appear in either of the fixed positions, potentially lessening the activity of the right-lateralised ventral network that subserves reorientation to unexpected stimuli[2,15]. To assess the utility of this task, we examined its relationship with the line bisection test in neurologically intact adults
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