Executive Brain Networks Research Articles

Prefrontal activation when suppressing an automatic balance recovery step

BackgroundThe present study investigated neural mechanisms for suppressing a highly automatic balance recovery step. Response inhibition has typically been researched using focal hand reaction tasks performed by seated participants, and this has revealed a neural stopping network including the Inferior Frontal Gyrus (IFG). It is unclear if the same neural networks contribute to suppressing an unwanted balance reaction. Research questionIs there greater IFG activation when suppressing an automatic balance recovery step? MethodsFunctional near-infrared spectroscopy (fNIRS) was used to measure brain activity in 21 young adults as they performed a balance recovery task that demanded rapid step suppression following postural perturbation. The hypothesis was that the IFG would show heightened activity when suppressing an automatic balance recovery step. A lean and-release system was used to impose temporally unpredictable forward perturbations by releasing participants from a supported forward lean. For most trials (80%), participants were told to recover balance by quickly stepping forward (STEP). However, on 20% of trials at random, a high-pitch tone was played immediately after postural perturbation signaling participants to suppress a step and fully relax into a catch harness (STOP). This allowed us to target the ability to cancel an already initiated step in a balance recovery context. Average oxygenated hemoglobin changes were contrasted between STEP and STOP trials, 1–6 s post perturbation. ResultsThe results showed a greater bilateral prefrontal response during STOP trials, supporting the idea that executive brain networks are active when suppressing a balance recovery step. SignificanceOur study demonstrates one way in which higher brain processes may help us prevent falls in complex environments where behavioral flexibility is necessary. This study also presents a novel method for assessing response inhibition in an upright postural context where rapid stepping reactions are required.

Moderate Exercise Improves Brain Efficiency for Executive Functions in Young Adults

This study investigates how moderate and addictive exercise influence the executive function network of the brain using fMRI. Sixty-five healthy participants performed the Wisconsin Card Sorting Test (WCST) during a functional magnetic resonance imaging (fMRI) scan. Participants were divided into three groups, according to the Korean exercise addiction scale (K-EAS): addictive exercise (AE), moderate exercise (ME), and no exercise (NE). We compared the extracted volumes of activity from the fMRI data between groups and analyzed the correlation between the volumes and the behavioral data. The activated area in the executive function network was significantly smaller in the AE and ME groups than in the NE group. In contrast, there was no difference between the AE and the ME group in the size of the activated area of the executive function network. The groups did not differ in behavioral performance. There was no significant correlation between the behavioral measurements and the activation volumes. A focused reorganization of the executive brain network through exercise may suggest improved neural efficiency for executive functions, and exercise may be helpful in maintaining executive functions and behavioral performance levels. Addictive exercise did not show an added benefit for the efficiency of executive functions.

Reduced dynamic functional connectivity between salience and executive brain networks in insomnia disorder.

SummaryResearch into insomnia disorder has pointed to large‐scale brain network dysfunctions. Dynamic functional connectivity is instrumental to cognitive functions but has not been investigated in insomnia disorder. This study assessed between‐network functional connectivity strength and variability in patients with insomnia disorder as compared with matched controls without sleep complaints. Twelve‐minute resting‐state functional magnetic resonance images and T1‐weighed images were acquired in 65 people diagnosed with insomnia disorder (21–69 years, 48 female) and 65 matched controls without sleep complaints (22–70 years, 42 female). Pairwise correlations between the activity time series of 14 resting‐state networks and temporal variability of the correlations were compared between cases and controls. After false discovery rate correction for multiple comparisons, people with insomnia disorder and controls did not differ significantly in terms of mean between‐network functional connectivity strength; people with insomnia disorder did, however, show less functional connectivity variability between the anterior salience network and the left executive‐control network. The finding suggests less flexible interactions between the networks during the resting state in people with insomnia disorder.

I am Me: Brain systems integrate and segregate to establish a multidimensional sense of self

Humans experience a sense of self, which is proposed to emerge from the integration of intrinsic and extrinsic self-processing through the propagation of information across brain systems. Using a novel functional magnetic resonance imaging (fMRI) paradigm, we tested this hypothesis in a non-clinical sample by modulating the intrinsic and extrinsic self-relatedness of auditory action consequences in terms of identity and agency, respectively. In addition, the relevance of individual traits associated with altered self-experiences (e.g., psychosis-like experiences) was examined. The task-evoked fMRI results showed distinctive associations between the neural coding of identity and negative affect traits, and between agency and psychosis-like experiences. Most importantly, regarding the functional connectivity analysis, graph theoretical measures demonstrated that the simultaneous processing of identity and agency relies on the functional integration and segregation of default mode, sensorimotor, language, and executive brain networks. Finally, cross-network interactions mediated by executive and sensorimotor regions were negatively associated with psychosis-like experiences when the intrinsic and extrinsic self-relatedness of action consequences conflicted. These findings provide evidence that the self is a multidimensional phenomenon rooted in the functional interactions between large-scale neuronal networks. Such interactions may have particular relevance for self-experience alterations.

Age group differences in executive network functional connectivity and relationships with social behavior in men with autism spectrum disorder

BackgroundResearch suggests adults with autism spectrum disorder (ASD) may use executive functions to compensate for social difficulties. Given hallmark age-related declines in executive functioning and the executive brain network in normal aging, there is concern that older adults with ASD may experience further declines in social functioning as they age. In a male-only sample, we hypothesized: 1) older adults with ASD would demonstrate greater ASD-related social behavior than young adults with ASD, 2) adults with ASD would demonstrate a greater age group reduction in connectivity of the executive brain network than neurotypical (NT) adults, and 3) that behavioral and neural mechanisms of executive functioning would predict ASD-related social difficulties in adults with ASD. MethodsParticipants were a cross-sectional sample of non-intellectually disabled young (ages 18–25) and middle-aged (ages 40-70) adult men with ASD and NT development (young adult ASD: n = 24; middle-age ASD: n = 25; young adult NT: n = 15; middle-age NT: n = 21). We assessed ASD-related social behavior via the self-report Social Responsiveness Scale-2 (SRS-2) Total Score, with exploratory analyses of the Social Cognition Subscale. We assessed neural executive function via connectivity of the resting-state executive network (EN) as measured by independent component analysis. Correlations were investigated between SRS-2 Total Scores (with exploratory analyses of the Social Cognition Subscale), EN functional connectivity of the dorsolateral prefrontal cortex (dlPFC), and a behavioral measure of executive function, Tower of London (ToL) Total Moves. ResultsWe did not confirm a significant age group difference for adults with ASD on the SRS-2 Total Score; however, exploratory analysis revealed middle-age men with ASD had higher scores on the SRS-2 Social Cognition Subscale than young adult men with ASD. Exacerbated age group reductions in EN functional connectivity were confirmed (left dlPFC) in men with ASD compared to NT, such that older adults with ASD demonstrated the greatest levels of hypoconnectivity. A significant correlation was confirmed between dlPFC connectivity and the SRS-2 Total Score in middle-age men with ASD, but not young adult men with ASD. Furthermore, exploratory analysis revealed a significant correlation with the SRS-2 Social Cognition Subscale for young and middle-aged ASD groups and ToL Total Moves. ConclusionOur findings suggest that ASD-related difficulties in social cognition and EN hypoconnectivity may get worse with age in men with ASD and is related to executive functioning. Further, exacerbated EN hypoconnectivity associated with older age in ASD may be a mechanism of increased ASD-related social cognition difficulties in older adults with ASD. Given the cross-sectional nature of this sample, longitudinal replication is needed.

Pre-scan cortisol is differentially associated with enhanced connectivity to the cognitive control network in young adults with a history of depression

BackgroundWe have previously demonstrated that pre-scan salivary cortisol is associated with attentuated frontal-subcortical brain activation during emotion processesing and semantic list-learning paradigms in depressed subjects. Additionally, altered functional connectivity is observed after remission of acute depression symptoms (rMDD). It is unknown whether cortisol also predicts altered functional connectivity during remission. MethodsParticipants were 47 healthy controls (HC) and 73 rMDD, 18–30 years old who provided salivary cortisol samples before and after undergoing resting-state fMRI. We tested whether salivary cortisol by diagnosis interactions were associated with seed-based resting connectivity of the default mode (DMN) and salience and emotion (SN) networks using whole-brain, cluster-level corrected (p < .01) regression in SPM8. ResultsPre-scan cortisol predicted decreased (HC) and increased (rMDD) cross-network connectivity to the dorsal anterior cingulate, dorso-medial and lateral- prefrontal cortex, brain stem and cerebellum (all seeds) and precuneus (DMN seeds). By and large, pre/post-scan cortisol change predicted the same pattern of findings. In network analyses, cortisol predominantly predicted enhanced cross-network connectivity to cognitive control network regions in rMDD. ConclusionsThe association of cortisol with connections of default and salience networks to executive brain networks differs between individuals with and without a history of depression. Further investigation is needed to better understand the role of cortisol and related stress hormones as a potential primary and interactive driver of network coherence in depression.

Abnormal medial prefrontal cortex functional connectivity and its association with clinical symptoms in chronic low back pain.

Accumulating evidence has shown that complicated brain systems are involved in the development and maintenance of chronic low back pain (cLBP), but the association between brain functional changes and clinical outcomes remains unclear. Here, we used resting-state functional magnetic resonance imaging (fMRI) and multivariate pattern analysis to identify abnormal functional connectivity (FC) between the default mode, sensorimotor, salience, and central executive brain networks in cLBP and tested whether abnormal FCs are related to pain and comorbid symptoms. Fifty cLBP patients and 44 matched healthy controls (HCs) underwent an fMRI scan, from which brain networks were identified by independent component analysis. Multivariate pattern analysis, graph theory approaches, and correlation analyses were applied to find abnormal FCs that were associated with clinical symptoms. Findings were validated on a second cohort of 30 cLBP patients and 30 matched HCs. Results showed that the medial prefrontal cortex/rostral anterior cingulate cortex had abnormal FCs with brain regions within the default mode network and with other brain networks in cLBP patients. These altered FCs were also correlated with pain duration, pain severity, and pain interference. Finally, we found that resting-state FC could discriminate cLBP patients from HCs with 91% accuracy in the first cohort and 78% accuracy in the validation cohort. Our findings suggest that the medial prefrontal cortex/rostral anterior cingulate cortex may be an important hub for linking the default mode network with the other 3 networks in cLBP patients. Elucidating the altered FCs and their association with clinical outcomes will enhance our understanding of the pathophysiology of cLBP and may facilitate the development of pain management approaches.

Functional Connectivity of Frontoparietal and Salience/Ventral Attention Networks Have Independent Associations With Co-occurring Attention-Deficit/Hyperactivity Disorder Symptoms in Children With Autism

BackgroundChildren with autism spectrum disorder (ASD) and co-occurring attention-deficit/hyperactivity disorder (ADHD) symptoms have worse functional outcomes and treatment response than those without ADHD symptoms. There is limited knowledge of the neurobiology of ADHD symptoms in ASD. Here, we test the hypothesis that aberrant functional connectivity of two large-scale executive brain networks implicated in ADHD—the frontoparietal and salience/ventral attention networks—also play a role in ADHD symptoms in ASD. MethodsWe compared resting-state functional connectivity of the two executive brain networks in children with ASD (n = 77) and typically developing control children (n = 82). These two executive brain networks comprise five subnetworks (three frontoparietal, two salience/ventral attention). After identifying aberrant functional connections among subnetworks, we examined dimensional associations with parent-reported ADHD symptoms. ResultsWeaker functional connectivity in ASD was present within and between the frontoparietal and salience/ventral attention subnetworks. Decreased functional connectivity within a single salience/ventral attention subnetwork, as well as between two frontoparietal subnetworks, significantly correlated with ADHD symptoms. Furthermore, follow-up linear regressions demonstrated that the salience/ventral attention and frontoparietal subnetworks explain unique variance in ADHD symptoms. These executive brain network–ADHD symptom relationships remained significant after controlling for ASD symptoms. Finally, specificity was also demonstrated through the use of a control brain network (visual) and a control co-occurring symptom domain (anxiety). ConclusionsThe present findings provide novel evidence that both frontoparietal and salience/ventral attention networks’ weaker connectivities are linked to ADHD symptoms in ASD. Moreover, co-occurring ADHD in the context of ASD is a source of meaningful neural heterogeneity in ASD.

Biopsychosocial Influences That Promote and Impede Social Brain Maturation

ABSTRACTSocial, emotional, and executive function systems of the brain change greatly during adolescence as the result of biopsychosocial influences. These factors alter the course of adolescent behavior through effects on the component processes of social behavior. Specifically, the influences of chronic stress, social and economic adversity, alcohol and drugs, and brain injury as well as parental buffering and support, increased neural connectivity and mentalizing resources, and enriched environments can impede or promote maturation of the social and executive brain networks that regulate social adjustment and emotional expression. Hence, there are many early “windows of opportunity” to affect the biological and neurocognitive foundations of adolescent social executive functions such as empathy, theory of mind, self-monitoring, and social emotions.

A case of somatopsychic depersonalization in schizotypal disorder: A multimodal approach

Background In the general concept of self-disturbances in schizophrenia and schizophrenia spectrum disorders, somatopsychic depersonalization (SPD) occupies a special place, as it constitutes a syndrome that comprises feelings of detachment from one's own body and mental processes. However, apart from clinical descriptions, to date the pathophysiology of SPD is not fully understood due to the rareness of the syndrome and a lack of experimental studies. Methods In a case study of one patient with schizotypal disorder (M.M., male, 29 y.o.), we applied a multimodal evaluation (phenomenological, neuropsychological, behavioural, application of fMRI paradigm) in order to understand the SPD phenomena. Results The patient's clinical profile was identified as disruption of implicit bodily function, accompanied by depressive symptoms. On a neuropsychological level, the patient exhibited impairment in executive functioning, intact tactile perception and kinesthetic praxis. Behavioral tests revealed an altered sense of time but unimpaired self-agency. Furthermore, the patient exhibited a lack of empathy and he had autistic traits, although with a sufficient ability to verbalize his feelings. On the neurobiological level using an active and passive touch paradigm during functional magnetic resonance imaging (fMRI), we found a hyperconnectivity of the default-mode network and salience network and a hypoconnectivity of the central executive brain networks in the performance of the touch task as well as intact perceptual touch processing emerging from the direct comparisons of the touch conditions. Conclusions Our data provide evidence for the important role of altered large-brain network functioning in SPD that corresponds to the specific behavioral and neurocognitive phenomena.

Neurocognitive and Neuroplastic Mechanisms of Novel Clinical Signs in CRPS.

Complex regional pain syndrome (CRPS) is a chronic, debilitating pain condition that usually arises after trauma to a limb, but its precise etiology remains elusive. Novel clinical signs based on body perceptual disturbances have been reported, but their pathophysiological mechanisms remain poorly understood. Investigators have used functional neuroimaging techniques (including MEG, EEG, fMRI, and PET) to study changes mainly within the somatosensory and motor cortices. Here, we provide a focused review of the neuroimaging research findings that have generated insights into the potential neurocognitive and neuroplastic mechanisms underlying perceptual disturbances in CRPS. Neuroimaging findings, particularly with regard to somatosensory processing, have been promising but limited by a number of technique-specific factors (such as the complexity of neuroimaging investigations, poor spatial resolution of EEG/MEG, and use of modeling procedures that do not draw causal inferences) and more general factors including small samples sizes and poorly characterized patients. These factors have led to an underappreciation of the potential heterogeneity of pathophysiology that may underlie variable clinical presentation in CRPS. Also, until now, neurological deficits have been predominantly investigated separately from perceptual and cognitive disturbances. Here, we highlight the need to identify neurocognitive phenotypes of patients with CRPS that are underpinned by causal explanations for perceptual disturbances. We suggest that a combination of larger cohorts, patient phenotyping, the use of both high temporal, and spatial resolution neuroimaging methods, and the identification of simplified biomarkers is likely to be the most fruitful approach to identifying neurocognitive phenotypes in CRPS. Based on our review, we explain how such phenotypes could be characterized in terms of hierarchical models of perception and corresponding disturbances in recurrent processing involving the somatosensory, salience and executive brain networks. We also draw attention to complementary neurological factors that may explain some CRPS symptoms, including the possibility of central neuroinflammation and neuronal atrophy, and how these phenomena may overlap but be partially separable from neurocognitive deficits.

Differential patterns of functional and structural plasticity within and between inferior frontal gyri support training-induced improvements in inhibitory control proficiency.

Ample evidence indicates that inhibitory control (IC), a key executive component referring to the ability to suppress cognitive or motor processes, relies on a right-lateralized fronto-basal brain network. However, whether and how IC can be improved with training and the underlying neuroplastic mechanisms remains largely unresolved. We used functional and structural magnetic resonance imaging to measure the effects of 2 weeks of training with a Go/NoGo task specifically designed to improve frontal top-down IC mechanisms. The training-induced behavioral improvements were accompanied by a decrease in neural activity to inhibition trials within the right pars opercularis and triangularis, and in the left pars orbitalis of the inferior frontal gyri. Analyses of changes in brain anatomy induced by the IC training revealed increases in grey matter volume in the right pars orbitalis and modulations of white matter microstructure in the right pars triangularis. The task-specificity of the effects of training was confirmed by an absence of change in neural activity to a control working memory task. Our combined anatomical and functional findings indicate that differential patterns of functional and structural plasticity between and within inferior frontal gyri enhanced the speed of top-down inhibition processes and in turn IC proficiency. The results suggest that training-based interventions might help overcoming the anatomic and functional deficits of inferior frontal gyri manifesting in inhibition-related clinical conditions. More generally, we demonstrate how multimodal neuroimaging investigations of training-induced neuroplasticity enable revealing novel anatomo-functional dissociations within frontal executive brain networks.

Acupuncture de qi in stable somatosensory stroke patients: relations with effective brain network for motor recovery.

Acupuncture has been widely used for treating stroke and De Qi may play an important role. In spite of its acceptance, the neural mechanism underlying acupuncture for motor recovery is still elusive. Particularly, by what extent De Qi sensations can reliably predict the therapeutical acupuncture effect on the mediating recovery from stroke is urgent to investigate. Nine stroke patients were assessed by De Qi, neurological examination, and scanned with acupuncture stimuli across two time points at an interval of two weeks. And we adopted multivariate Granger causality analysis to explore the interregional influences within motor executive brain network during post-acupuncture resting state. Our findings indicated that acupuncture at GB34 can enhance the recovery of stroke mainly by strengthening causal influences between the ipsilesional and contralesional motor cortex. Moreover, centrality of some motor-related regions correlated with clinical variables and thus served as a predictor of stroke recovery. Along the same line, the centrality of these motor-related regions has also high relations with the De Qi sensation. Our findings suggest that De Qi having relatively stable reliability may be essential and used as a predictor to the therapeutic effectiveness of acupuncture for stroke recovery.

In Vivo Structural and Functional Imaging of the Human Rubral and Inferior Olivary Nuclei: A Mini-review

Few imaging studies have been devoted to the structural and functional connectivity of the red and inferior olivary nuclei although these two nuclei represent two main targets of the cerebellum within the brainstem. However, the RN is anatomically and functionally related to a widespread sensorimotor, limbic, and executive brain network. It projects massively onto the principal olive with which it contributes to a cerebello-rubro-olivo-cerebellar loop modulated by cortical and subcortical afferents. Despite a minor role in planning and execution of rhythmic movements, the red nucleus in conjunction with the inferior olive, more specifically involved in the detection of "unexpected" events, contributes to sensorimotor, sensory and, likely, cognitive higher functions.