Neural synchrony indexes impaired motor slowing after errors and novelty following white matter damage

Error-related brain activity: A time-domain and time-frequency investigation in pediatric obsessive-compulsive disorder

Increased error-related negativity (ERN), a measure of error monitoring, has been suggested as a biomarker of obsessive-compulsive disorder (OCD). Additional insight into error monitoring is possible using time-frequency decomposition of electroencephalographic (EEG) data, as it allows disentangling the brain's parallel processing of information. Greater error-related theta is thought to reflect an error detection signal, while delta activity may reflect more elaborative post-detection processes (i.e., strategic adjustments). Recent investigations show that decreased error-related alpha may index attentional engagement following errors; additionally, increases and decreases in error-related beta could reflect motor inhibition and motor preparation, respectively. However, time-frequency dynamics of error monitoring in OCD are largely unknown. The present study examined time-frequency theta, delta, alpha and beta power in early adolescents with OCD using a data-driven, cluster-based approach. The aim was to explore electrocortical measures of error monitoring in early adolescents with (n = 27, 15 females) and without OCD (n = 27, 14 females) during an arrowhead version of the flanker task while EEG activity was recorded. Results indicated that the OCD group was characterized by increased ERN and error-related theta, as well as reduced error-related beta power decrease (i.e., greater power) compared to participants without OCD. Greater error-related beta explained variance in OCD over and above the ERN and error-related theta. By examining separate time-frequency measures, the present study provides novel insights into the dynamics of error monitoring, suggesting that pediatric OCD may be characterized by enhanced error monitoring (i.e., greater theta power) and post-error inhibition (i.e., reduced beta power decrease).

Error-related brain activity in pediatric major depressive disorder: An ERP and time-frequency investigation

BACKGROUND

The error-related negativity (ERN) reflects individual differences in error monitoring. However, findings on the ERN in adult and adolescent depression have been inconsistent. Analyzing electroencephalographic (EEG) data in both the time- and time-frequency domain can be useful to better quantify neural response to errors. The present study aimed at examining electrocortical measures of error monitoring in early adolescents with and without depression.

METHOD

EEG activity was collected during an arrowhead version of the flanker task in 29 (25 females) early adolescents with depression and 34 without MDD (29 females).

RESULTS

The depression group showed reduced ERN amplitude, reduced error-related theta power and increased error-related beta power compared to the control group. When all variables that related to MDD diagnosis were considered simultaneously, both theta and beta power, but not the ERN, were independently related to an increased likelihood of being diagnosed with depression.

CONCLUSIONS

By examining both time-domain and separate time-frequency measures, the present study provided novel evidence on error monitoring alterations in youth depression, suggesting that depression during adolescence may be characterized by reduced error monitoring (i.e., reduced ERN and error-related theta) and post-error inhibition (i.e., greater error-related beta power). These results support that time-frequency measures might be better suited for examining error-related neural activity in MDD relative to time-domain measures.

M/EEG Dynamics Underlying Reserve, Resilience, and Maintenance in Aging: A Review

Cognitive reserve and resilience refer to the set of processes allowing the preservation of cognitive performance in the presence of structural and functional brain changes. Investigations of these concepts have provided unique insights into the heterogeneity of cognitive and brain changes associated with aging. Previous work mainly relied on methods benefiting from a high spatial precision but a low temporal resolution, and thus the temporal brain dynamics underlying these concepts remains poorly known. Moreover, while spontaneous fluctuations of neural activity have long been considered as noise, recent work highlights its critical contribution to brain functions. In this study, we synthesized the current state of knowledge from magnetoencephalography (MEG) and electroencephalography (EEG) studies that investigated the contribution of maintenance of neural synchrony, and variability of brain dynamics, to cognitive changes associated with healthy aging and the progression of neurodegenerative disease (such as Alzheimer's disease). The reviewed findings highlight that compensations could be associated with increased synchrony of higher (>10 Hz) frequency bands. Maintenance of young-like synchrony patterns was also observed in healthy older individuals. Both maintenance and compensation appear to be highly related to preserved structural integrity (brain reserve). However, increased synchrony was also found to be deleterious in some cases and reflects neurodegenerative processes. These results provide major elements on the stability or variability of functional networks as well as maintenance of neural synchrony over time, and their association with individual cognitive changes with aging. These findings could provide new and interesting considerations about cognitive reserve, maintenance, and resilience of brain functions and cognition.

Doing it Wrong: A Systematic Review on Electrocortical and Behavioral Correlates of Error Monitoring in Patients with Neurological Disorders

Detecting errors in one's own and other's actions is a crucial ability for learning and adapting behavior to everchanging, highly volatile environments. Studies in healthy people demonstrate that monitoring errors in one's own and others' actions are underpinned by specific neural systems that are dysfunctional in a variety of neurological disorders. In this review, we first briefly discuss the main findings concerning error detection and error awareness in healthy subjects, the current theoretical models, and the tasks usually applied to investigate these processes. Then, we report a systematic search for evidence of dysfunctional error monitoring among neurological populations (basal ganglia, neurodegenerative, white-matter diseases and acquired brain injury). In particular, we examine electrophysiological and behavioral evidence for specific alterations of error processing in neurological disorders. Error-related negativity (ERN) amplitude were reduced in most (although not all) neurological patient groups, whereas Positivity Error (Pe) amplitude appeared not to be affected in most patient groups. Also theta activity was reduced in some neurological groups, but consistent evidence on the oscillatory activity has not been provided thus far. Behaviorally, we did not observe relevant patterns of pronounced dysfunctional (post-) error processing. Finally, we discuss limitations of the existing literature, conclusive points, open questions and new possible methodological approaches for clinical studies.

Executive function in children with sickle cell anemia on transfusion: NIH toolbox utility in the clinical context

OBJECTIVE

The aim of this study was to establish the utility of the NIH Toolbox as a cognitive screener of executive functions in the clinical context. Additionally, we aimed to investigate whether age and time on transfusion were related to executive function performance. Method: Twenty-eight children and adolescents with sickle cell anemia (SCA) between 8 and 18 years (M = 13.28, SD = 3.05) on transfusion treatment were included. Participants completed five NIH Toolbox tasks (three executive function tasks and two non-executive function control tasks). Results: Mean scores on one of the three executive function measures (inhibitory control) fell below the average range (M = 81.36, SD = 14.01) with approximately 70% of children from both groups below the average range. Scores for processing speed (M = 86.82, SD = 22.01) and cognitive flexibility (M = 85.75, SD = 12.67) were low averages. As expected, scores on non-executive measures (language and memory) fell within the average range. No significant differences were observed between children with silent stroke and no stroke on executive function measures. Older age (p < .01) and length of time on transfusion (p < .05) predicted lower inhibitory control scores. Conclusions: Findings provide evidence for poor development of inhibitory control with age in this patient population. As the NIH Toolbox successfully highlighted expected deficits in this patient population, this study supports the use of this tool as a brief screening measure for children with SCD. The clinical and theoretical implications of the findings are discussed.

Theta-Band Functional Connectivity and Single-Trial Cognitive Control in Sports-Related Concussion: Demonstration of Proof-of-Concept for a Potential Biomarker of Concussion

OBJECTIVES

This report examined theta-band neurodynamics for potential biomarkers of brain health in athletes with concussion.

METHODS

Participants included college-age contact/collision athletes with (N=24) and without a history of concussion (N=16) in Study 1. Study 2 (N=10) examined changes over time in contact/collision athletes. There were two primary dependent variables: (1) theta-band phase-synchronization (e.g., functional connectivity) between medial and right-lateral electrodes; and (2) the within-subject correlation between synchronization strength on error trials and post-error reaction time (i.e., operationalization of cognitive control).

RESULTS

Head injury history was inversely related with medial-lateral connectivity. Head injury was also related to declines in a neurobehavioral measure of cognitive control (i.e., the single-trial relationship between connectivity and post-error slowing).

CONCLUSIONS

Results align with a theory of connectivity-mediated cognitive control. Mild injuries undetectable by behavioral measures may still be apparent on direct measures of neural functioning. This report demonstrates that connectivity and cognitive control measures may be useful for tracking recovery from concussion. Theoretically relevant neuroscientific findings in healthy adults may have applications in patient populations, especially with regard to monitoring brain health. (JINS 2019, 25, 314-323).

Ready for change: Oscillatory mechanisms of proactive motor control

Proactive motor control is a preparatory mechanism facilitating upcoming action inhibition or adaptation. Previous studies investigating proactive motor control mostly focused on response inhibition, as in the classical go-nogo or stop-signal tasks. However, everyday life rarely calls for the complete suppression of actions without subsequent behavioral adjustment. Therefore, we conducted a modified cued go-nogo-change task, in which cues indicated whether participants might have to change to an alternative action or inhibit the response to an upcoming target. Based on the dual-mechanisms of control framework and using electroencephalography (EEG), we investigated the role of the sensorimotor cortex and of prefrontal regions in preparing to change and cancel motor responses. We focused on mu and beta power over sensorimotor cortex ipsi- and contralateral to an automatic motor response and on prefrontal beta power. Over ipsilateral sensorimotor cortex, mu and beta power was relatively decreased when anticipating to change or inhibit the automatic motor behavior. Moreover, alpha phase coupling between ipsilateral motor cortex and prefrontal areas decreased when preparing to change, suggesting a decoupling of sensorimotor regions from prefrontal control. When the standard motor action actually had to be changed, prefrontal beta power increased, reflecting enhanced cognitive control. Our data highlight the role of the ipsilateral motor cortex in preparing to inhibit and change upcoming motor actions. Here, especially mu power and phase coupling seem to be critical to guide upcoming behavior.

An adaptive orienting theory of error processing

The ability to detect and correct action errors is paramount to safe and efficient goal-directed behaviors. Existing work on the neural underpinnings of error processing and post-error behavioral adaptations has led to the development of several mechanistic theories of error processing. These theories can be roughly grouped into adaptive and maladaptive theories. While adaptive theories propose that errors trigger a cascade of processes that will result in improved behavior after error commission, maladaptive theories hold that error commission momentarily impairs behavior. Neither group of theories can account for all available data, as different empirical studies find both impaired and improved post-error behavior. This article attempts a synthesis between the predictions made by prominent adaptive and maladaptive theories. Specifically, it is proposed that errors invoke a nonspecific cascade of processing that will rapidly interrupt and inhibit ongoing behavior and cognition, as well as orient attention toward the source of the error. It is proposed that this cascade follows all unexpected action outcomes, not just errors. In the case of errors, this cascade is followed by error-specific, controlled processing, which is specifically aimed at (re)tuning the existing task set. This theory combines existing predictions from maladaptive orienting and bottleneck theories with specific neural mechanisms from the wider field of cognitive control, including from error-specific theories of adaptive post-error processing. The article aims to describe the proposed framework and its implications for post-error slowing and post-error accuracy, propose mechanistic neural circuitry for post-error processing, and derive specific hypotheses for future empirical investigations.

Proactive Control: Neural Oscillatory Correlates of Conflict Anticipation and Response Slowing

Proactive control allows us to anticipate environmental changes and adjust behavioral strategy. In the laboratory, investigators have used a number of different behavioral paradigms, including the stop-signal task (SST), to examine the neural processes of proactive control. Previous functional MRI studies of the SST have demonstrated regional responses to conflict anticipation-the likelihood of a stop signal or P(stop) as estimated by a Bayesian model-and reaction time (RT) slowing and how these responses are interrelated. Here, in an electrophysiological study, we investigated the time-frequency domain substrates of proactive control. The results showed that conflict anticipation as indexed by P(stop) was positively correlated with the power in low-theta band (3-5 Hz) in the fixation (trial onset)-locked interval, and go-RT was negatively correlated with the power in delta-theta band (2-8 Hz) in the go-locked interval. Stimulus prediction error was positively correlated with the power in the low-beta band (12-22 Hz) in the stop-locked interval. Further, the power of the P(stop) and go-RT clusters was negatively correlated, providing a mechanism relating conflict anticipation to RT slowing in the SST. Source reconstruction with beamformer localized these time-frequency activities close to brain regions as revealed by functional MRI in earlier work. These are the novel results to show oscillatory electrophysiological substrates in support of trial-by-trial behavioral adjustment for proactive control.

Temporal Dynamics of Proactive and Reactive Motor Inhibition

Proactive motor inhibition refers to endogenous preparatory mechanisms facilitating action inhibition, whereas reactive motor inhibition is considered to be a sudden stopping process triggered by external signals. Previous studies were inconclusive about the temporal dynamics of involved neurocognitive processes during proactive and reactive motor control. Using electroencephalography (EEG), we investigated the time-course of proactive and reactive inhibition, measuring event-related oscillations and event-related potentials (ERPs). Participants performed in a cued go/nogo paradigm with cues indicating whether the motor response might or might not have to be inhibited. Based on the dual mechanisms of control (DMC) framework by Braver, we investigated the role of attentional effects, motor preparation in the sensorimotor cortex and prefrontal cognitive control mechanisms, separating effects before and after target onset. In the cue-target interval, proactive motor inhibition was associated with increased attention, reflected in reduced visual alpha power and an increased contingent negative variation (CNV). At the same time, motor inhibition was modulated by reduced sensorimotor beta power. After target onset, proactive inhibition resulted in an increased N1, indicating allocation of attention towards relevant stimuli, increased prefrontal beta power and a modulation of sensorimotor mu activity. As in previous studies, reactive stopping of motor actions was associated with increased prefrontal beta power and increased sensorimotor beta activity. The results stress the relevance of attentional mechanisms for proactive inhibition and speak for different neurocognitive mechanisms being involved in the early preparation for and in later implementation of motor inhibition.

Mutant Tau knock-in mice display frontotemporal dementia relevant behaviour and histopathology

Models of Tau pathology related to frontotemporal dementia (FTD) are essential to determine underlying neurodegenerative pathologies and resulting tauopathy relevant behavioural changes. However, existing models are often limited in their translational value due to Tau overexpression, and the frequent occurrence of motor deficits which prevent comprehensive behavioural assessments. In order to address these limitations, a forebrain-specific (CaMKIIα promoter), human mutated Tau (hTauP301L+R406W) knock-in mouse was generated out of the previously characterised PLB1Triple mouse, and named PLB2Tau. After confirmation of an additional hTau species (~60kDa) in forebrain samples, we identified age-dependent progressive Tau phosphorylation which coincided with the emergence of FTD relevant behavioural traits. In line with the non-cognitive symptomatology of FTD, PLB2Tau mice demonstrated early emerging (~6months) phenotypes of heightened anxiety in the elevated plus maze, depressive/apathetic behaviour in a sucrose preference test and generally reduced exploratory activity in the absence of motor impairments. Investigations of cognitive performance indicated prominent dysfunctions in semantic memory, as assessed by social transmission of food preference, and in behavioural flexibility during spatial reversal learning in a home cage corner-learning task. Spatial learning was only mildly affected and task-specific, with impairments at 12months of age in the corner learning but not in the water maze task. Electroencephalographic (EEG) investigations indicated a vigilance-stage specific loss of alpha power during wakefulness at both parietal and prefrontal recording sites, and site-specific EEG changes during non-rapid eye movement sleep (prefrontal) and rapid eye movement sleep (parietal). Further investigation of hippocampal electrophysiology conducted in slice preparations indicated a modest reduction in efficacy of synaptic transmission in the absence of altered synaptic plasticity. Together, our data demonstrate that the transgenic PLB2Tau mouse model presents with a striking behavioural and physiological face validity relevant for FTD, driven by the low level expression of mutant FTD hTau.