Figure 4.

Top row: The locations for the 19 electrode channels (“A1” and “A2” were not used). Those 2 electrodes (“C3” and “P3”) highlighted in dashed violet circles are the selected electrodes from the proposed approach. Bottom rows: First two columns: observed current source density (CSD) curves from the selected electrodes X₄ (“C3”) and X₅ (“P3”) (each electrode corresponds to each row), over the Alpha band (8 to 12 Hz), for the placebo A = 1 arm (in the first column) and the active drug A = 2 arm (in the second column), measured before treatment. The arm-specific mean functions are overlaid as dashed green curves. Third column: the estimated single-index coefficient functions (β₄ and β₅) for the selected channels X₄ and X₅ (with the associated 95% confidence bands, conditioning on the jth partial residual and ${\widehat{g}}_j$).