Disentangling gaze shifts from preparatory ERP effects during spatial attention

Authors


  • This experiment was realized using Cogent (http://www.vislab.ucl.ac.uk/Cogent) and analyzed using SPM (http://www.fil.ion.ucl.ac.uk/spm). Stefan Kiebel, James Kilner, and Rik Henson gave advice on using SPM functions for EEG analysis. This research was supported by Wellcome Trust grants to J.D. and M.E. J.D. and M.E. also hold Royal Society-Wolfson Research Merit Awards.

Address reprint requests to: Dr. Steffan Kennett, UCL Institute of Cognitive Neuroscience, 17 Queen Square, London, WC1N 3AR, UK.

Abstract

After a cue directing attention to one side, anterior event-related potentials (ERPs) show contralateral negativity (anterior directing attention negativity, ADAN). It is unclear whether ADAN effects are contaminated by contralateral negativity arising from residual gaze shifts. Conversely, it is possible that ADAN-related potentials contaminate the horizontal electrooculogram (HEOG), via volume conduction. To evaluate these possibilities, we used high-resolution infrared eye tracking while recording EEG and HEOG in a cued spatial-attention task. We found that, after conventional ERP and HEOG preprocessing exclusions, small but systematic residual gaze shifts in the cued direction can remain, as revealed by the infrared measure. Nevertheless, by using this measure for more stringent exclusion of small gaze shifts, we confirmed that reliable ADAN components remain for preparatory spatial attention in the absence of any systematic gaze shifts toward the cued side.

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