| Abstract No.: | C-D3141 |
| Country: | Canada |
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| Title: | NEURAL CORRELATES OF SACCADE CONTROL IN THE DEVELOPING BRAIN BY USING FMRI |
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| Authors/Affiliations: | 1 Nadia Alahyane*; 1 Brian Coe; 1 Patrick W. Stroman; 1 James N. Reynolds; 1 Doug P. Munoz;
1 Queen's University, Kingston, ON, Canada
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| Content: | The performance of saccadic eye movements improves throughout childhood, the voluntary control maturing later than the automatic control. Important developmental brain changes occurring in children might impact this saccade control improvement. Objectives: Our study aims at examining developmental differences in neural correlates of saccade control in children and adults. Materials and Methods: We combined functional magnetic resonance imaging (fMRI) and eye movement recording in a group of normal children (11-13 years) and adults (20-25 years) performing interleaved prosaccade and antisaccade tasks based upon a given instruction (colour of a central visual cue). The prosaccade task probes the ability to initiate an automatic saccade toward a peripheral visual stimulus. The antisaccade task probes the ability to suppress the automatic response to the stimulus and instead initiate a voluntary saccade to an opposite position. In addition to prosaccade and antisaccade trials, the event-related fMRI design included catch trials that contained only the instructional cue and no peripheral stimulus presentation. Catch trials provide a measure of the instruction related processes during fMRI whereas saccade trials contain both instruction and response related components. Results: First, catch trials revealed that adults showed significantly greater activation for antisaccade instruction than prosaccade instruction in frontal eye fields (FEF), supplementary eye fields (SEF), parietal eye fields (PEF), caudate nucleus, and dorsolateral prefrontal cortex (DLPFC). We also investigated the response related activation by contrasting the catch trials to the saccade trials and found that adults exhibited greater activation for the antisaccade response in FEF, SEF and PEF. Second, our data revealed differences of activation between children and adults. Catch trials revealed that children exhibited greater activation during antisaccade instruction than prosaccade instruction in the same fronto-parieto-subcortical network as adults, but with a larger extent for DLPFC. Unlike the adults, children also exhibited greater activation for antisaccade instruction in the thalamus. However, the amplitude of the fMRI signal change was significantly lower in children as compared to adults for all the fronto-parietal-subcortical network except for SEF. Lastly, children and adults had similar response-related activation in FEF and PEF. Conclusion: These findings indicate age-related differences in the organization of brain systems subserving voluntary saccade control during normal development, in particular during the instruction period of the oculomotor tasks. |
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