Comparison of ‘chosen’ and ‘non-chosen’ responses: Global field potential (GFP).

<div><p>(A) Single-electrode traces (33 channels) for chosen (magenta) and non-chosen (blue) responses, grand averaged across presentation intervals and subjects. Grey patches demarcate times during which there was a significant difference between GFP for the chosen and non-chosen stimuli (see B and C). The pink patches demarcate areas of significant topographic dissimilarity (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0068928#pone-0068928-g004" target="_blank">Figure 4</a>).</p> <p>(B) GFP for responses to stimuli ‘chosen’ as different (magenta) and ‘non-chosen’ (blue). These measures are independent of topography differences. Grey patches are as above.</p> <p>(C) Statistical analysis of the GFP: A permutation test was run to control for family-wise error rate (FWER) associated with multiple comparisons across the ERP time-course. The t-statistic associated with the difference between chosen and non-chosen GFP is in black, and criterion t-value controlling for the FWER is marked by the dashed red line. The grey areas demarcate time points at which the t-statistic exceeded the criterion value.</p> <p>(D) Topographic plots showing the difference between chosen and non-chosen activity at various time-points with significant GFP differences. The color bar indicates differences in microvolts.</p>