Fig. 2.

Conflict related theta activity in the STN and mesial frontal cortex. (A) Top row shows STN theta power aligned such that t = 0 corresponds to the stimulus onset (left) or the response (right). High conflict trials showed significantly higher pre-response STN theta power (see solid arrows and black bars). A post-response difference can also be seen as the post-high conflict theta power is higher during the “baseline” period of the subsequent trial (see line arrows). Black line denotes significant time points that survived correction for multiple comparisons (p < 0.05, permutation testing). Group average percentage change ± SEM are shown for all plots. Bottom row is same as top row but for mesial frontal theta power. Note STN theta power peaked before the response while mesial frontal theta power peaked after the response. (B) Same as A, but for inter-trial phase consistency (ITPC). There were no significant time points that showed a conflict related difference. Note both the STN and mesial frontal cortex increases in ITPC occurred at the same time and earlier than the theta power increases in either site. (C) Same as A, but for the inter-site phase coherence. High conflict trials showed significantly higher pre-response coherence between the STN and the mesial frontal. This increase occurred at the same time as the increase in ITPC, suggesting that though both low and high conflict trials show a increase in phase consistency early in the trial (before the theta power increase), only during conflict are the phases synchronized between the two brain regions.