Figure 1.
Overview of task (A) and behavioral results (B).
“L” and “R” indicate trials in which the stimulus was presented on the left and right side of the screen, respectively. “cC” and “cI” indicate congruent and incongruent trials, respectively, following congruent trials.
Figure 2.
Sensor- and source-level topographical maps of task-related theta band (4–8 Hz) power.
(A) Topographical maps over time (columns) in ms after stimulus onset, averaged across all conditions (top row), for incongruent-congruent trials separately for trials with left hemifield presentation (“L: I-C”) and right hemifield presentation, and for incongruent-congruent trials pooling across both left- and right-hemifield trials. Gray and white circles indicate electrodes in which the condition difference is significant at p<0.00078125 (0.05/64, thus correcting for multiple comparisons across electrodes) and p<0.005 (uncorrected), respectively. Time-frequency plots are from midfrontal electrode FCz. (B) Source-reconstructed theta power from the statistical contrast of all incongruent vs. congruent trials. X, Y, and Z correspond to MNI coordinates of displayed slices. (C) Theta power (in dB relative to pre-stimulus baseline) from all voxels in the region illustrated in panel B plotted separately for each condition and for the “conflict effect” (incongruent minus congruent trials). “hemif.” stands for “hemifield” of stimulus presentation. Top two plots show activity on trials following congruent trials; bottom two plots show activity on trials following incongruent trials. Error bars are standard errors of the mean. Data in B and C are taken from the average of 200 to 600 ms.
Figure 3.
Same asFigure 2, but for conflict modulation of alpha-band (8–12 Hz) power.
Bar plots in panel C show power from the contralateral hemifield activations shown in panel B (red/yellow blobs). Data in B and C are taken from the average of 600 to 900 ms.
Figure 4.
Same asFigures 2 and 3, but for gamma-band power (30–50 Hz).
Data in B and C are taken from the average of 200 to 400 ms. Units on the y-axis are dB change from pre-stimulus baseline period.
Figure 5.
Source-space connectivity analysis seeded from the MFC region exhibiting a significant theta conflict effect (see red blob in Figure 2b) reveals theta-band connectivity (trial-to-trial power correlations) with left lateral prefrontal cortex.
Bar plots show average correlation coefficients, with error bars reflecting standard errors of the mean, across subjects. Numbers under bars indicate p-values of correlation coefficients of each condition, tested across subjects against zero. Note that the contrast was defined as stronger correlations for incongruent compared to congruent trials, pooling across both left- and right-hemifield conditions.
Figure 6.
Similar toFigure 5, except the seed region was parietal gamma (see orange blobs in Figure 3b) from 200–400 ms, and the connectivity region shown here is in the theta band from 250 to 600 ms.
Figure 7.
Connectivity time courses reveal dynamics of conflict-induced network shifts.
Y-axis shows the difference in correlation coefficients for incongruent minus congruent trials (averaging across left- and right-hemifield trials; positive numbers indicate stronger coupling during incongruent trials, and negative numbers indicate stronger coupling during congruent trials). = connectivity between medial frontal theta and lateral frontal theta, see Figure 5a–c;
= connectivity between medial frontal theta and parietal alpha, see Figure 5d–f;
= connectivity between parietal gamma and ventrolateral frontal theta, see Figure 6.
Figure 8.
Correlations between brain conflict effects (localized band-specific power in A and network connectivity in B) and the behavior conflict effect.
Brain data reflect the same time-frequency-space windows as used in previous figures; behavior conflict effect refers to individual differences in cI-cC RTs. Results show that subjects with stronger MFC-LFC theta networks, and subjects with stronger right parietal gamma-VLPFC theta networks, expressed less conflict at the behavioral level. Data are collapsed across left- and right-hemifield trials for MFC data (top row), because brain effects showed no laterality.