Cognitive control and midline theta adjust across multiple timescales

Concurrent expectation and experience-based metacontrol: EEG insights and the role of working memory capacity

We investigated the simultaneous influence of expectation and experience on metacontrol, which we define as the instantiation of context-specific control states. These states could entail heightened control states in preparation for frequent task switching or lowered control states for task repetition. Specifically, we examined whether "expectations" regarding future control demands prompt proactive metacontrol, while "experiences" with items associated with specific control demands facilitate reactive metacontrol. In Experiment 1, we utilized EEG with a high temporal resolution to differentiate between brain activities associated with proactive and reactive metacontrol. We successfully observed cue-locked and image-locked ERP patterns associated with proactive and reactive metacontrol, respectively, supporting concurrent instantiation of two metacontrol modes. In Experiment 2, we focused on individual differences to investigate the modulatory role of working memory capacity (WMC) in the concurrent instantiation of two metacontrol modes. Our findings revealed that individuals with higher WMC exhibited enhanced proactive metacontrol, indicated by smaller response time variability (RTV). Additionally, individuals with higher WMC showed a lower tendency to rely on reactive metacontrol, indicated by a smaller item-specific switch probability (ISSP) effect. In conclusion, our results suggest that proactive and reactive metacontrol can coexist, but their interplay is influenced by individuals' WMC. Higher WMC promotes the use of proactive metacontrol while attenuating reliance on reactive metacontrol. This study provides insights into the interplay between proactive and reactive metacontrol and highlights the impact of WMC on their concurrent instantiation.

Impaired proactive cognitive control in Parkinson's disease

Adaptive control has been studied in Parkinson's disease mainly in the context of proactive control and with mixed results. We compared reactive- and proactive control in 30 participants with Parkinson's disease to 30 age matched healthy control participants. The electroencephalographic activity of the participants was recorded over 128 channels while they performed a numerical Stroop task, in which we controlled for confounding stimulus-response learning. We assessed effects of reactive- and proactive control on reaction time-, accuracy- and electroencephalographic time-frequency data. Behavioural results show distinct impairments of proactive- and reactive control in participants with Parkinson's disease, when tested on their usual medication. Compared to healthy control participants, participants with Parkinson's disease were impaired in their ability to adapt cognitive control proactively and were less effective to resolve conflict using reactive control. Successful reactive and proactive control in the healthy control group was accompanied by a reduced conflict effect between congruent and incongruent items in midline-frontal theta power. Our findings provide evidence for a general impairment of proactive control in Parkinson's disease and highlight the importance of controlling for the effects of S-R learning when studying adaptive control. Evidence concerning reactive control was inconclusive, but we found that participants with Parkinson's disease were less effective than healthy control participants in resolving conflict during the reactive control task.

Effects of childhood institutionalization on semantic processing and its neural correlates persist into adolescence and adulthood

Individuals raised in institutionalized care settings are more likely to demonstrate developmental deficits than those raised in biological families. One domain that is vulnerable to the impoverished environments characteristic of some institutionalized care facilities is language development. We used EEG to assess ERPs and source-localized event-related spectral perturbations (ERSPs) associated with semantic processing at different levels of picture-word conflict and low versus high word frequency. Additionally, we assessed behavioral language ability (a synonyms task) and IQ. Participants (N = 454) were adolescents and adults with a history of institutionalized care (N = 187) or raised in biological families (N = 267), both recruited from secondary educational settings to approximately match the groups on age and education. Results indicate that individuals with a history of institutionalization are less accurate at judging whether semantic information in a spoken word matches an image. Additionally, those with a history of institutionalization show reduced cognitive control of conflict and more reactive N400 ERPs and beta ERSPs when handling picture-word conflict, especially in the left hemisphere. Frontal theta is related to semantic and conflict processing; however, in this study it did not vary with institutionalization.

Midfrontal Theta Activity Is Sensitive to Approach-Avoidance Conflict

Midfrontal theta (FMθ) in the human EEG is commonly viewed as a generic and homogeneous mechanism of cognitive control in general and conflict processing in particular. However, the role of FMθ in approach-avoidance conflicts and its cross-task relationship to simpler stimulus-response conflicts remain to be examined more closely. Therefore, we recorded EEG data while 59 healthy participants (49 female, 10 male) completed both an approach-avoidance task and a flanker task. Participants showed significant increases in FMθ power in response to conflicts in both tasks. To our knowledge, this is the first study to show a direct relationship between FMθ and approach-avoidance conflicts. Crucially, FMθ activity was task dependent and showed no cross-task correlation. To assess the possibility of multiple FMθ sources, we applied source separation [generalized eigendecomposition (GED)] to distinguish independent FMθ generators. The activity of the components showed a similar pattern and was again task specific. However, our results did not yield a clear differentiation between task-specific FMθ sources for each of the participants. Overall, our results show FMθ increases in approach-avoidance conflicts, as has been established only for more simple response conflict paradigms so far. The independence of task-specific FMθ increases suggests differential sensitivity of FMθ to different forms of behavioral conflict.SIGNIFICANCE STATEMENT FMθ is well established as an indicator for cognitive conflict in tasks involving simple stimulus-response conflicts. However, we do not yet know about its role in more complex forms of goal ambivalence, such as approach-avoidance conflicts. Thus, we implemented an approach-avoidance task and a flanker task to investigate FMθ in response to simple as well as more complex response conflicts. To our knowledge, this is the first study to show a direct relationship between FMθ and approach-avoidance conflicts. Although the transient FMθ increase is similar to that induced in a simple response conflict task, individual FMθ responsiveness to these two forms of conflict were independent of each other, suggesting intraindividual differences in the sensitivity of FMθ to different forms of behavioral conflict.

Electrophysiological Correlates of Social Decision-making: An EEG Investigation of a Modified Ultimatum Game

Cooperation behaviors during social decision-making have been shown to be sensitive to manipulations of context. However, it remains unclear how aspects of context in dynamic social interactions, such as observed nonverbal behaviors, may modulate cooperation decisions and the associated neural mechanisms. In this study, participants responded to offers from proposers to split $10 in an Ultimatum Game following observation of proposer approach (friendly) or avoidance (nonfriendly) behaviors, displayed by dynamic whole-body animated avatars, or following a nonsocial interaction control condition. As expected, behavioral results showed that participants tended to have greater acceptance rates for unfair offers following observed nonverbal social interactions with proposers compared with control, suggesting an enhancing effect of social interactions on cooperative decisions. ERP results showed greater N1 and N2 responses at the beginning of social interaction conditions compared with control, and greater sustained and late positivity responses for observed approach and avoidance proposer behaviors compared with control. Event-related spectral perturbation (ERSP) results showed differential sensitivity within theta, alpha, and beta bands during observation of social interactions and offers that was associated with subsequent decision behaviors. Together, these results point to the impact of proposers' nonverbal behaviors on subsequent cooperation decisions at both behavioral and neural levels. The ERP and ERSP findings suggest modulated attention, monitoring, and processing of biological motion during the observed nonverbal social interactions, influencing the participants' responses to offers. These findings shed light on electrophysiological correlates of response to observed social interactions that predict subsequent social decisions.

Auditory spatial attention gradients and cognitive control as a function of vigilance

Selection and effort are central to attention, yet it is unclear whether they draw on a common pool of cognitive resources, and if so, whether there are differences for early versus later stages of cognitive processing. This study assessed effort by quantifying the vigilance decrement, and spatial processing at early and later stages as a function of time-on-task. Participants performed an auditory spatial attention task, with occasional "catch" trials requiring no response. Psychophysiological measures included bilateral cerebral blood flow (transcranial Doppler), pupil dilation, and blink rate. The shape of attention gradients using reaction time indexed early processing, and did not significantly vary over time. Later stimulus-response conflict was comparable over time, except for a reduction to left hemispace stimuli. Target and catch trial accuracy decreased with time, with a more abrupt decrease for catch versus target trials. Diffusion decision modeling found progressive decreases in information accumulation rate and non-decision time, and the adoption of more liberal response criteria. Cerebral blood flow increased from baseline and then decreased over time, particularly in the left hemisphere. Blink rate steadily increased over time, while pupil dilation increased only at the beginning and then returned towards baseline. The findings suggest dissociations between resources for selectivity and effort. Measures of high subjective effort and temporal declines in catch trial accuracy and cerebral blood flow velocity suggest a standard vigilance decrement was evident in parallel with preserved selection. Different attentional systems and classes of computations that may account for dissociations between selectivity versus effort are discussed.

Widespread theta coherence during spatial cognitive control

Cognitive control allows humans to process relevant sensory information while minimizing distractions from irrelevant stimuli. The neural basis of cognitive control is known to involve frontal regions of the brain such as the medial prefrontal cortex (mPFC) and anterior cingulate cortex (ACC), but the temporal dynamics of larger scale networks is unclear. Here we used EEG with source localization to identify how the neural oscillations localized to the mPFC and ACC coordinate with parietal, sensory, and motor areas during spatial cognitive control. Theta coherence (3-8 Hz) between the mPFC and ACC increased with task difficulty and predicted individual differences in reaction time. Individual differences in accuracy were predicted by earlier activation of ACC-motor coherence, highlighting the relationship between processing speed and task performance. Our results provide evidence that successful cognitive control requires dynamic coordination between a widespread network of brain regions. Long range theta coherence may be a key mechanism for efficient cognitive control across the neocortex.

Modality-specific neural mechanisms of cognitive control in a Stroop-like task

The successful resolution of ever-changing conflicting contexts requires efficient cognitive control. Previous studies have found similar neural patterns in conflict processing for different modalities using an event-related potential (ERP) approach and have concluded that cognitive control is supramodal. However, recent behavioral studies have found that conflict adaptation (a phenomenon with the reduction of congruency effect in the current trial after an incongruent trial as compared with a congruent trial) could not transfer across visual and auditory modalities and suggested that cognitive control is modality-specific, challenging the supramodal view. These discrepancies may have also arisen from methodological differences across studies. The current study examined the electroencephalographic profiles of a Stroop-like task to elucidate the modality-specific neural mechanisms of cognitive control. Participants were instructed to respond to a target always coming from the visual modality while disregarding the distractor coming from either the auditory or the visual modality. The results revealed significant congruency effects on both behavioral indices, i.e., reaction time and error rate, and ERP components, including the P3 and the conflict slow potential. Besides, the congruency effects on the amplitude of the P3 showed a negative correlation with reaction time, indicating an intrinsic link between these neural and behavioral indices. Furthermore, in the modality-repetition condition, conflict adaptation effects were significant on both reaction time and P3 amplitude, and the reaction time could be predicted by the P3 amplitude, while such effects were not observed in the modality-alternation condition. The time-frequency analysis also showed that conflict adaptation occurred in the modality-repetition condition, but not in the modality-alternation condition in low frequency bands, including the theta (4-8 Hz), alpha (8-12 Hz), and beta1 (12-20 Hz) bands. Taken together, our results revealed modality-specific patterns of the conflict adaptation effects on the P3 amplitude and oscillatory power (in theta, alpha, and beta1 bands), providing neural evidence for the modality specificity of cognitive control and expanding the boundaries of cognitive control.

Salient distractors open the door of perception: alpha desynchronization marks sensory gating in a working memory task

Focusing attention on relevant information while ignoring distracting stimuli is essential to the efficacy of working memory. Alpha- and theta-band oscillations have been linked to the inhibition of anticipated and attentionally avoidable distractors. However, the neurophysiological background of the rejection of task-irrelevant stimuli appearing in the focus of attention is not fully understood. We aimed to examine whether theta and alpha-band oscillations serve as an indicator of successful distractor rejection. Twenty-four students were enrolled in the study. 64-channel EEG was recorded during a modified Sternberg working memory task where weak and strong (salient) distractors were presented during the retention period. Event-related spectral perturbation in the alpha frequency band was significantly modulated by the saliency of the distracting stimuli, while theta oscillation was modulated by the need for cognitive control. Moreover, stronger alpha desynchronization to strong relative to weak distracting stimuli significantly increased the probability of mistakenly identifying the presented distractor as a member of the memory sequence. Therefore, our results suggest that alpha activity reflects the vulnerability of attention to distracting salient stimuli.

Cognitive control involves theta power within trials and beta power across trials in the prefrontal-subthalamic network

There is increasing evidence that the medial prefrontal cortex participates in conflict and feedback monitoring while the subthalamic nucleus adjusts actions. Yet how these two structures coordinate their activity during cognitive control remains poorly understood. We recorded from the human prefrontal cortex and the subthalamic nucleus simultaneously while participants (n = 22) performed a novel task involving high conflict trials, complete response inhibition trials, and trial-to-trial behavioural adaptations to conflict and errors. Overall, we found that within-trial adaptions to both conflict and complete response inhibition involved changes in the theta band while across-trial behavioural adaptations to both conflict and errors involved changes in the beta band (P < 0.05). Yet the role each region's theta and beta oscillations played during the task differed significantly between the two sites. Trials that involved either within-trial conflict or complete response inhibition were associated with increased theta phase synchrony between the medial prefrontal cortex and the subthalamic nucleus (P < 0.05). Despite increased synchrony, however, increases in prefrontal theta power were associated with response inhibition, while increases in subthalamic theta power were associated with response execution (P < 0.05). In the beta band, post-response increases in prefrontal beta power were suppressed when the completed trial contained either conflict or an erroneous response (P < 0.05). Subthalamic beta power, on the other hand, was only modified during the subsequent trial that followed a conflict or error trial. Notably, these adaptation trials exhibited slower response times (P < 0.05), suggesting that both brain regions contribute to across-trial adaptations but do so at different stages of the adaptation process. Taken together, our data shed light on the mechanisms underlying within-trial and across-trial cognitive control and how disruption of this network can negatively impact cognition. More broadly, however, our data also demonstrate that the specific role of a brain region, rather than the frequency being utilized, governs the behavioural correlates of oscillatory activity.