Neural oscillations are thought to provide a cyclic time frame for orchestrating brain computations. Following this assumption, midfrontal theta oscillations have recently been proposed to temporally organize brain computations during conflict processing. Using a multivariate analysis approach, we show that brain-behavior relationships during conflict tasks are modulated according to the phase of ongoing endogenous midfrontal theta oscillations recorded by scalp EEG. We found reproducible results in two independent datasets, using two different conflict tasks: brain-behavior relationships (correlation between reaction time and theta power) were theta phase-dependent in a subject-specific manner, and these “behaviorally optimal” theta phases were also associated with fronto-parietal cross-frequency dynamics emerging as theta phase-locked beta power bursts. These effects were present regardless of the strength of conflict. Thus, these results provide empirical evidence that midfrontal theta oscillations are involved in cyclically orchestrating brain computations likely related to response execution during the tasks rather than purely related to conflict processing. More generally, this study supports the hypothesis that phase-based computation is an important mechanism giving rise to cognitive processing.

According to embodied simulation theory, understanding other people’s emotions is fostered by facial mimicry. However, studies assessing the effect of facial mimicry on the recognition of emotion are still controversial. In Parkinson’s disease (PD), one of the most distinctive clinical features is facial amimia, a reduction in facial expressiveness, but patients also show emotional disturbances. The present study used the pathological model of PD to examine the role of facial mimicry on emotion recognition by investigating EMG responses in PD patients during a facial emotion recognition task (anger, joy, neutral). Our results evidenced a significant decrease in facial mimicry for joy in PD, essentially linked to the absence of reaction of the zygomaticus major and the orbicularis oculi muscles in response to happy avatars, whereas facial mimicry for expressions of anger was relatively preserved. We also confirmed that PD patients were less accurate in recognizing positive and neutral facial expressions and highlighted a beneficial effect of facial mimicry on the recognition of emotion. We thus provide additional arguments for embodied simulation theory suggesting that facial mimicry is a potential lever for therapeutic actions in PD even if it seems not to be necessarily required in recognizing emotion as such.

35Neural oscillations are thought to provide a cyclic time frame for orchestrating brain 36 computations. Following this assumption, midfrontal theta oscillations have recently been 37 proposed to temporally organize brain computations during conflict processing. Using a 38 multivariate analysis approach, we show that brain-behavior relationships during conflict 39 tasks are modulated according to the phase of ongoing endogenous midfrontal theta 40 oscillations recorded by scalp EEG. We found reproducible results in two independent 41 datasets, using two different conflict tasks: brain-behavior relationships (correlation between 42 reaction time and theta power) were theta phase-dependent in a subject-specific manner, and 43 these "behaviorally optimal" theta phases were also associated with fronto-parietal cross-44 frequency dynamics emerging as theta phase-locked beta power bursts. These effects were 45 present regardless of the strength of conflict. Thus, these results provide empirical evidence 46 that midfrontal theta oscillations are involved in cyclically orchestrating brain computations 47 likely related to response execution during the tasks rather than purely related to conflict 48 processing. More generally, this study supports the hypothesis that phase-based computation 49 is an important mechanism giving rise to cognitive processing. 50 51