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Left, not right, congruency effects in the flanker task activate frontoparietal and control networks

Poster Session A - Saturday, March 7, 3:00 – 5:00 pm, Fairview/Kitsilano Ballrooms

Stefania Konstantopoulou¹, Bianca Borsarini¹, Sélim Coll¹, Emilie Marti¹, Radek Ptak^1,2; ¹Network Plasticity Modulation (NetPM) Lab, Department of Clinical Neuroscience, Faculty of Medicine, University of Geneva, Geneva, Switzerland, ²Division of Neurorehabilitation, Geneva University Hospitals, Geneva, Switzerland

Introduction: The congruency effect in the flanker task is generally considered to reflect executive control processes and inhibition. Previous studies have shown that incongruent flankers tend to engage fronto-cingulate networks responsible for conflict monitoring and response selection. We here show that when the flanker is unilateral and congruency is defined by color, the congruency effect for flankers in the left hemifield activates bilateral fronto-parietal networks in addition to the cingulate cortex. Methods: Forty-five healthy adults (26 females; mean age = 61.7 years) performed a color-based flanker task during fMRI acquisition. They were required to react to a central, colored target preceded by a single left or right flanker of the same (congruent, ConL or ConR) or a different (incongruent, IncL or IncR) color. Data were pre-processed and analyzed using SPM. Contrasts were computed with main effects and interactions of congruency and side. Whole-brain results were corrected for age and FWE-thresholded at p < .05. Results: Compared to each other, left and right flankers activated contralateral occipito-temporal cortex, irrespective of congruency. When comparing the congruency effects for left flankers (IncL-ConL > IncR-ConR) we found bilateral activation of frontoparietal regions, including the dorsolateral prefrontal cortex (dlPFC), frontal eye field (FEF), dorsal anterior cingulate (dACC), visual and motor areas. The reverse contrast did not yield any significant results. Conclusions: Our findings show that only the congruency effect associated with left flankers triggers a strong bilateral activation of attention and executive networks, suggesting a bias in the left hemifield toward conflicting information.

Topic Area: ATTENTION: Spatial