Differential Patterns of Theta Activation Underlying Various Cognitive Control Strategies

In this study, EEG was recorded from 157 participants at the University of Arkansas as they performed three computer tasks that tested inhibitory control (Go/Nogo Task), proactive and reactive control (AX-Continuous Performance Task), and resolving response conflict (Global/Local Task- modified Flanker Task). Time-frequency analysis (ERSP) was the primary focus of this study, in order to take advantage of the temporal and frequential characteristics of EEG recordings. The ERSPs and following statistical analysis showed significantly higher midfrontal theta band (4-8 Hz) power values for target trials (those that required more cognitive control) than control trials, which indicated that the procedure was implemented correctly. Furthermore, statistical analysis revealed that reactive control and inhibitory control had significantly higher theta power values than both proactive control and response conflict, and that proactive control had significantly higher theta power values than response conflict. Taken together, these results suggest a common underlying physiological mechanism for initiating and executing cognitive control, namely frontal midline theta band oscillations, but how these oscillations are integrated into cognitive processing still remains unclear. The results of this study suggest that theta power might be an important factor in allowing frontal midline brain regions to differentiate cognitive control mechanisms, but further work will need to be completed to investigate the role of theta power and theta phase in establishing and coordinating cognitive control

Neuroimaging and Genetics Studies of the Role of Right Prefrontal Cortex in Controlled Attention.

Maintaining goal-relevant behavior requires controlled attention, especially when attention is challenged by distraction. Deficits in controlled attention are characteristic of a number of disorders, including schizophrenia. Here I present three studies investigating the human neural correlates of successful attentional control, specifically those associated with stabilizing performance during distractor challenge. To optimize the translational potential of this work, the present studies used the Sustained Attention Task (SAT) and its distractor condition (dSAT) which has been validated for use in both humans and rodent models, and has been identified as a promising tool for understanding attention deficits in schizophrenia (Luck et al., 2012). The first study, using BOLD fMRI, found that a region in right inferior frontal gyrus approximating Broadmann’s Area (BA) 9 showed increased activation in response to the distractor. This right mid-dorsal/dorsolateral prefrontal cortex region is part of the frontoparietal cognitive control network, and multivariate analyses charting its functional connections to other regions revealed that increases in connectivity between BA 9 and posterior parietal cortex were associated with successful behavioral resistance to distraction. A second study using electrophysiological methods complemented these findings by showing a similar correlation between increases in theta phase-locking during distractor challenge and optimal performance. Finally, the third study used genetic variation to probe the role of the cholinergic system, which rodent studies employing SAT and dSAT suggest is critical for attention. Specifically, in rodents, the maintenance of performance during distraction is associated with increases in acetylcholine in right prefrontal cortex. Consistent with rodent findings, the present work in humans suggested a role of acetylcholine in distractor-related activation increases in right BA 9. Participants with a genetic polymorphism thought to limit cholinergic release capacity showed diminished distractor-evoked right BA 9 activation increases. Together, these findings further specify the neural correlates of controlled attention in humans, and take the first steps in linking these measures to the human cholinergic system. The ultimate goal of this research is to capitalize on the strengths of both human-based and animal model-based investigations of attention to contribute to the identification of therapeutic targets to treat deficits where they may exist.PhDNeuroscienceUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/108932/1/asberry_1.pd

Improving cognitive control: Is theta neurofeedback training associated with proactive rather than reactive control enhancement?

Frontal-midline (FM) theta activity (4–8 Hz) is proposed to reflect a mechanism for cognitive control that is needed for working memory retention, manipulation, and interference resolution. Modulation of FM theta activity via neurofeedback training (NFT) demonstrated transfer to some but not all types of cognitive control. Therefore, the present study investigated whether FM theta NFT enhances performance and modulates underlying EEG characteristics in a delayed match to sample (DMTS) task requiring mainly proactive control and a color Stroop task requiring mainly reactive control. Moreover, temporal characteristics of transfer were explored over two posttests. Across seven 30-min NFT sessions, an FM theta training group exhibited a larger FM theta increase compared to an active control group who upregulated randomly chosen frequency bands. In a posttest performed 13 days after the last training session, the training group showed better retention performance in the DMTS task. Furthermore, manipulation performance was associated with NFT theta increase for the training but not the control group. Contrarily, behavioral group differences and their relation to FM theta change were not significant in the Stroop task, suggesting that NFT is associated with proactive but not reactive control enhancement. Transfer to both tasks at a posttest one day after training was not significant. Behavioral improvements were not accompanied by changes in FM theta activity, indicating no training-induced modulation of EEG characteristics. Together, these findings suggest that NFT supports transfer to cognitive control that manifests late after training but that other training-unspecific factors may also contribute to performance enhancement

EEG, MEG and neuromodulatory approaches to explore cognition: Current status and future directions

Neural oscillations and their association with brain states and cognitive functions have been object of extensive investigation over the last decades. Several electroencephalography (EEG) and magnetoencephalography (MEG) analysis approaches have been explored and oscillatory properties have been identified, in parallel with the technical and computational advancement. This review provides an up-to-date account of how EEG/MEG oscillations have contributed to the understanding of cognition. Methodological challenges, recent developments and translational potential, along with future research avenues, are discussed. Keywords: Cognition; Electrophysiology; Event-related-potentials; Neural oscillations; Neural synchronisation; Neuromodulatio

Oscillatory Control over Representational States in Working Memory

In the visual world, attention is guided by perceptual goals activated in visual working memory (VWM). However, planning multiple-task sequences also requires VWM to store representations for future goals. These future goals need to be prevented from interfering with the current perceptual task. Recent findings have implicated neural oscillations as a control mechanism serving the implementation and switching of different states of prioritization of VWM representations. We review recent evidence that posterior alpha-band oscillations underlie the flexible activation and deactivation of VWM representations and that frontal delta-to-theta-band oscillations play a role in the executive control of this process. That is, frontal delta-to-theta appears to orchestrate posterior alpha through long-range oscillatory networks to flexibly set up and change VWM states during multitask sequences

Frontal cortex differentiates between free and imposed target selection in multiple-target search

Cognitive control can involve proactive (preparatory) and reactive (corrective) mechanisms. Using a gaze-contingent eye tracking paradigm combined with fMRI, we investigated the involvement of these different modes of control and their underlying neural networks, when switching between different targets in multiple-target search. Participants simultaneously searched for two possible targets presented among distractors, and selected one of them. In one condition, only one of the targets was available in each display, so that the choice was imposed, and reactive control would be required. In the other condition, both targets were present, giving observers free choice over target selection, and allowing for proactive control. Switch costs emerged only when targets were imposed and not when target selection was free. We found differential levels of activity in the frontoparietal control network depending on whether target switches were free or imposed. Furthermore, we observed core regions of the default mode network to be active during target repetitions, indicating reduced control on these trials. Free and imposed switches jointly activated parietal and posterior frontal cortices, while free switches additionally activated anterior frontal cortices. These findings highlight unique contributions of proactive and reactive control during visual search

Adaptiveness in proactive control engagement in children and adults

Age-related progress in cognitive control reflects more frequent engagement of proactive control during childhood. As proactive preparation for an upcoming task is adaptive only when the task can be reliably predicted, progress in proactive control engagement may rely on more efficient use of contextual cue reliability. Developmental progress may also reflect increasing efficiency in how proactive control is engaged, making this control mode more advantageous with age. To address these possibilities, 6-year-olds, 9-year-olds, and adults completed three versions of a cued task-switching paradigm in which contextual cue reliability was manipulated. When contextual cues were reliable (but not unreliable or uninformative), all age groups showed greater pupil dilation and a more pronounced (pre)cue-locked posterior positivity associated with faster response times, suggesting adaptive engagement of proactive task selection. However, adults additionally showed a larger contingent negative variation (CNV) predicting a further reduction in response times with reliable cues, suggesting motor preparation in adults but not children. Thus, early developing use of contextual cue reliability promotes adaptiveness in proactive control engagement from early childhood; yet, less efficient motor preparation in children makes this control mode overall less advantageous in childhood than adulthood