Functional Integrity of Executive Control Network Contributed to Retained Executive Abilities in Mild Cognitive Impairment

Background: Mild cognitive impairment (MCI) is considered to be a transitional state between normal aging and Alzheimer's dementia (AD). Recent studies have indicated that executive function (EF) declines during MCI. However, only a limited number of studies have investigated the neural basis of EF deficits in MCI. Herein, we investigate the changes of regional brain spontaneous activity and functional connectivity (FC) of the executive control network (ECN) between high EF and low EF groups.Methods: According to EF composite score (ADNI-EF) from the Alzheimer's Disease Neuroimaging Initiative (ADNI), we divided MCI into two groups, including the MCI-highEF group and MCI-lowEF group. Resting-state functional MRI was utilized to investigate the fractional amplitude of low-frequency fluctuation (fALFF) and ECN functional connectivity across 23 healthy controls (HC), 11 MCI-highEF, and 14 MCI-lowEF participants. Moreover, a partial correlation analysis was carried out to examine the relationship between altered fALFF or connectivity of the ECN and the ADNI-EF.Results: Compared to HC, the MCI-highEF participants demonstrated increased fALFF in the left superior temporal gyrus (STG), as well as decreased fALFF in the right precentral gyrus, right postcentral gyrus, and left middle frontal gyrus (MFG). The MCI-lowEF participants demonstrated increased fALFF in the cerebellar vermis and decreased fALFF in the left MFG. Additionally, compared to HC, the MCI-highEF participants indicated no significant difference in connectivity of the ECN. Furthermore, the MCI-lowEF participants showed increased ECN FC in the left cuneus and left MFG, as well as decreased ECN functional connectivity in the right parahippocampal gyrus (PHG). Notably, the altered fALFF in the left MFG was positively correlated to ADNI-EF, while the altered fALFF in cerebellar vermis is negatively correlated with ADNI-EF across the two MCI groups and the HC group. Altered ECN functional connectivity in the right PHG is negatively correlated to ADNI-EF, while altered ECN functional connectivity in the left cuneus is negatively correlated to ADNI-EF across the three groups.Conclusions: Our current study demonstrates the presence of different patterns of regional brain spontaneous activity and ECN FC in the MCI-highEF group and MCI-lowEF group. Furthermore, the ECN FC of the MCI-highEF group was not disrupted, which may contribute to retained EF in MCI.

Disrupted dynamic network reconfiguration of the executive and reward networks in internet gaming disorder: Why IGD subjects cannot control their gaming cravings

BackgroundStudies have shown that people with internet gaming disorder (IGD) show impaired executive control over their gaming cravings; however, the neural mechanisms underlying this process remain unknown. In addition, these conclusions were based on the hypothesis that brain networks were temporally stationary and neglected changes in cognitive processes.MethodsResting-state fMRI data were collected from 402 subjects (162 subjects with IGD and 240 recreational game users (RGUs)). The community structure (recruitment and integration) of the executive control network and the basal ganglia network (BGN, representing the reward network) of patients with IGD and healthy controls were analyzed and compared. Mediation effects were analyzed among the different networks.ResultsWhen compared to RGUs, subjects with IGD had a lower recruitment coefficient within the right executive control network (ECN). Further analysis showed that only male subjects had a lower recruitment coefficient. Mediation analysis showed that the integration coefficient of the right ECN mediated the relationship between the recruitment coefficients of both the right ECN and the BGN in RGUs.ConclusionsSubjects with IGD had a lower recruitment coefficient than RGUs, and this feature was only observed in male subjects, making them less efficient at impulse control. The meditation results suggest a top-down control mechanism of the ECN is missing in subjects with IGD. All of these findings could explain why subjects with IGD have impaired executive control over their gaming cravings.

Effects of Mini-Basketball Training Program on Social Communication Impairment and Executive Control Network in Preschool Children with Autism Spectrum Disorder

This study evaluated the effect of a 12-week mini-basketball training program (MBTP) on social communication (SC) and the executive control network (ECN) in preschool children with autism spectrum disorders (ASD). We finally assigned 30 preschool children with ASD to an experiment group (n = 15, 12 males, 3 females) or a control group (n = 15, 13 males, 2 females). The experiment group participated in a 12-week MBTP (40-min sessions per day, 5 days a week), while the control group only received the institutional routine behavioral rehabilitation intervention. The SC of preschool children with ASD was measured using the Social Responsiveness Scale, Second Edition (SRS-2), whereas functional connectivity (FC) of the ECN was assessed using resting-state functional magnetic resonance imaging (rs-fMRI) at pre-and post-test. Our results showed that SC exhibited significant improvement in the intervention group, especially in SRS-2 total score, social cognition, and social communication. We found significantly enhanced functional connectivity between the right cerebellum and left inferior frontal gyrus in the experimental group, while functional connectivity between the left middle temporal gyrus and right cerebellum were decreased in the control group. Furthermore, there were no significant correlations between the change in SC scores and FC of the ECN. Altogether, this study provides valuable insights that a 12-week MBTP improves SC and functional connectivity of the ECN in preschool children with ASD. We further inferred that neural mechanisms might be associated with changing the ECN of preschool ASD children caused by the 12-week MBTP.

Attentional Networks in Co-occurring Generalized Anxiety Disorder and Major Depression Disorder: Towards a Staging Hypothesis of the Executive Control Deficits

Background. Major Depression Disorder (MDD) and Generalized Anxiety Disorder (GAD) often co-occur, but the neurocognitive mechanisms of this co-occurrence remain unknown. Prominent views have pointed to attentional processes as potent mechanisms at play in MDD and GAD, respectively. Yet uncertainty remains regarding the very nature of attentional impairments in patients with co-occurring MDD and GAD. Methods. Inspired by contemporary models of attentional networks, we examined the integrity of the three main attentional networks, namely the alerting, orienting, and executive control networks, in patients with co-occurring MDD and GAD (n = 30), MDD only (n = 30), GAD only (n = 30), or neither MDD or GAD (n = 30).Results. Patients with co-occurring MDD and GAD exhibited more severe impairments in the executive control network than those with only one of the disorders. There were no differences between the executive control networks of patients with solely MDD or solely GAD, but both groups showed significantly more severe impairment than those without either MDD and GAD. Limitations. The cross-sectional study design precludes strong inference regarding the cause-effect relationship between the executive control network and the co-occurrence of MDD and GAD. Conclusions. Our findings align with a longstanding staging approach to comorbidity whereby, via synergistic effects, co-occurring disorders yield greater damage than the sum of each disorder. Here, for the first time, we extended this approach to the executive control network of attention in the context of the co-occurrence between MDD and GAD.

Cingulo-opercular control network and disused motor circuits joined in standby mode

Whole-brain resting-state functional MRI (rs-fMRI) during 2 wk of upper-limb casting revealed that disused motor regions became more strongly connected to the cingulo-opercular network (CON), an executive control network that includes regions of the dorsal anterior cingulate cortex (dACC) and insula. Disuse-driven increases in functional connectivity (FC) were specific to the CON and somatomotor networks and did not involve any other networks, such as the salience, frontoparietal, or default mode networks. Censoring and modeling analyses showed that FC increases during casting were mediated by large, spontaneous activity pulses that appeared in the disused motor regions and CON control regions. During limb constraint, disused motor circuits appear to enter a standby mode characterized by spontaneous activity pulses and strengthened connectivity to CON executive control regions.

Functional connectivity changes and cognitive deficits in Alzheimer’s disease: A review

This review discusses findings on resting-state intra- and internetwork functional connectivity in Alzheimer’s disease (AD) as measured with magnetic resonance imaging (MRI). It discusses the five most often cited networks observed as being altered in AD and attempts to link those to cognitive dysfunctions in AD. The default mode network shows a consistent decrease in intranetwork connectivity and a decreased suppression of specific areas, likely relating to impaired memory performance. Concerning the salience network, there might be a temporary increase in activity in certain regions in early AD, causing a heightened sensitivity to emotionally salient stimuli. However, ultimately, intranetwork connectivity is impaired, likely leading to attentional deficits as the SAL becomes less efficient at (dis)engaging other functional networks. The executive control network shows a trajectory similar to the SAL, with executive functions and language being most affected. The dorsal attention network is likely related to top-down attention orienting and shows a gradual connectivity decrease in AD, as does the sensorimotor network. Finally, the balance between these networks seems to be disturbed. Results suggest that functional connectivity alterations could be used as a biomarker for AD diagnosis.

Neuroimaging Findings in Adolescents and Young Adults with Anorexia Nervosa: A Systematic Review

Background: Anorexia nervosa (AN) is a serious, multifactorial mental disorder affecting predominantly young females. This systematic review examines neuroimaging findings in adolescents and young adults up to 24 years old, in order to explore alterations associated with disease pathophysiology. Methods: Eligible studies on structural and functional brain neuroimaging were sought systematically in PubMed, CENTRAL and EMBASE databases up to 5 October 2020. Results: Thirty-three studies were included, investigating a total of 587 patients with a current diagnosis of AN and 663 healthy controls (HC). Global and regional grey matter (GM) volume reduction as well as white matter (WM) microstructure alterations were detected. The mainly affected regions were the prefrontal, parietal and temporal cortex, hippocampus, amygdala, insula, thalamus and cerebellum as well as various WM tracts such as corona radiata and superior longitudinal fasciculus (SLF). Regarding functional imaging, alterations were pointed out in large-scale brain networks, such as default mode network (DMN), executive control network (ECN) and salience network (SN). Most findings appear to reverse after weight restoration. Specific limitations of neuroimaging studies in still developing individuals are also discussed. Conclusions: Structural and functional alterations are present in the early course of the disease, most of them being partially or totally reversible. Nonetheless, neuroimaging findings have been open to many biological interpretations. Thus, more studies are needed to clarify their clinical significance.

Psilocybin-induced changes in brain network integrity and segregation correlate with plasma psilocin level and psychedelic experience

The emerging novel therapeutic psilocybin produces psychedelic effects via engagement of cerebral serotonergic targets by psilocin (active metabolite). The serotonin 2A receptor critically mediates these effects by altering distributed neural processes that manifest as increased entropy, reduced functional connectivity (FC) within discrete brain networks (i.e., reduced integrity) and increased FC between networks (i.e., reduced segregation). Reduced integrity of the default mode network (DMN) is proposed to play a particularly prominent role in psychedelic phenomenology, including perceived ego-dissolution. Here, we investigate the effects of a psychoactive oral dose of psilocybin (0.2-0.3 mg/kg) on plasma psilocin level (PPL), subjective drug intensity (SDI) and their association in fifteen healthy individuals. We further evaluate associations between these measures and resting-state FC, measured with functional magnetic resonance imaging, acquired over the course of five hours after psilocybin administration. We show that PPL and SDI correlate negatively with measures of network integrity (including DMN) and segregation, both spatially constrained and unconstrained. We also find that the executive control network and dorsal attention network desegregate, increasing connectivity with other networks and throughout the brain as a function of PPL and SDI. These findings provide direct evidence that psilocin critically shapes the time course and magnitude of changes in the cerebral functional architecture and subjective experience following psilocybin administration. Our findings provide novel insight into the neurobiological mechanisms underlying profound perceptual experiences evoked by this emerging transnosological therapeutic and implicate the expression of network integrity and segregation in the psychedelic experience and consciousness.