Fig. 2.
Task-based functional connectivity (tb-fcMRI) time point selection approach used in the present study is shown on a simulated time series example. The bottom panel shows the overall original BOLD time series in light gray. The time series following overall task structure removal is shown in black and is substantially attenuated in overall variability. Negative and neutral events are marked in red and blue, respectively, across the figure. Event onset is shown at the bottom along the x-axis. The average of time points 4 and 5 following each event onset is marked with vertical red or blue bars spanning the y-axis of the bottom figure. The top panels show examples of 2 extracted and concatenated voxel trial-to-trial variability time series for neutral (left) and negative (right) conditions. All tb-fcMRI analyses are performed on these extracted time courses, which reflect variation in peak response following each distracter—as indicated by obtained correlation coefficients shown in corners of each top panel. As noted, this approach, along with removal of task structure, largely circumvents the concern that correlations are being driven by overall task response.