Inter-individual differences in intrinsic connectivity of the ocular motor network predict anti-saccade spatial accuracy

• ¹ University of Melbourne, Dept of Anatomy and Neuroscience, Australia
• ² Monash University, School of Psychological Sciences, Australia
• ³ Monash University, Monash Biomedical Imaging, Australia

Background: Anti-saccades (AS) are an equal and opposite ballistic eye movement away from a visual target. Compared to pro-saccades (PS), AS evoke enhanced fMRI responses in cortices involved in cognition and ocular motility such as frontal eye fields (FEF) and parietal cortex, and decreased responses in visual cortices such as V1 and lateral occipital cortex (LOC). We mapped the ocular motor network using fMRI during AS vs PS and explored the intrinsic connectivity of this network using resting-state (rsfMRI) connectivity analyses. We sought to determine whether inter-individual variation in patterns of connectivity of the AS network were associated with inter-individual variation in AS accuracy. Methods: Sixteen subjects performed randomised AS and PS trials in an event-related design during fMRI acquisition (TR/TE=30/2500ms; voxel size=3x3x3mm3) with video eye tracking, and 5-min rsfMRI. Regions of significantly increased or decreased fMRI response during AS vs PS informed the regions of interest (ROI) used in subsequent analyses. Group independent components analysis implemented in FSL was used to identify nodes within the ocular motor network. Average fMRI time-courses for each node in each subject were extracted and covariance matrices between nodes were calculated for each subject. Covariance between nodes was correlated subject-wise to average latency-corrected AS position error reflecting the spatial accuracy of the primary saccade. Results: Greater AS position error was associated with: 1) positive fMRI signal correlation between left and right FEF, 2) positive signal correlation between left and right LOC, and 3) negative signal correlation between FEF and LOC. Conclusions: Variation in functional connectivity between frontal and occipital cortices explains variation in AS spatial accuracy. Future work will investigate whether AS accuracy is associated with patterns of fMRI signal change shared between frontal and occipital regions on individual trials.