Functional Integrity Of Brain Research Articles

Stem Cell Therapy and Thiamine Deficiency-Induced Brain Damage.

Wernicke's encephalopathy (WE) is a major central nervous system disorder resulting from thiamine deficiency (TD) in which a number of brain regions can develop serious damage including the thalamus and inferior colliculus. Despite decades of research into the pathophysiology of TD and potential therapeutic interventions, little progress has been made regarding effective treatment following the development of brain lesions and its associated cognitive issues. Recent developments in our understanding of stem cells suggest they are capable of repairing damage and improving function in different maladys. This article puts forward the case for the potential use of stem cell treatment as a therapeutic strategy in WE by first examining the effects of TD on brain functional integrity and its consequences. The second half of the paper will address the future benefits of treating TD with these cells by focusing on their nature and their potential to effectively treat neurodegenerative diseases that share some overlapping pathophysiological features with TD. At the same time, some of the obstacles these cells will have to overcome in order to become a viable therapeutic strategy for treating this potentially life-threatening illness in humans will be highlighted.

Presynaptic density determined by SV2A PET is closely associated with postsynaptic metabotropic glutamate receptor 5 availability and independent of amyloid pathology in early cognitive impairment.

Metabotropic glutamate receptor 5 (mGluR5) is involved in regulating integrative brain function and synaptic transmission. Aberrant mGluR5 signaling and relevant synaptic failure play a key role in the pathophysiological mechanism of Alzheimer's disease (AD). Ten cognitively impaired (CI) individuals and 10 healthy controls (HCs) underwent [18F]SynVesT-1 and [18F]PSS232 positron emission tomography (PET)/magnetic resonance to assess synaptic density and mGluR5 availability. The associations between mGluR5 availability and synaptic density were examined. A mediation analysis was performed to investigate the possible mediating effects of mGluR5 availability and synaptic loss on the relationship between amyloid deposition and cognition. CI patients exhibited lower mGluR5 availability and synaptic density in the medial temporal lobe than HCs. Regional synaptic density was closely associated with regional mGluR5 availability. mGluR5 availability and synaptic loss partially mediated the relationship between amyloid deposition and cognition. Reductions in mGluR5 availability and synaptic density exhibit similar spatial patterns in AD and are closely linked. Cognitively impaired patients exhibited lower mGluR5 availability and synaptic density in the medial temporal lobe than HCs. Reductions in mGluR5 availability and synaptic density exhibit similar spatial patterns in AD. Regional synaptic density was closely associated with regional mGluR5 availability. mGluR5 availability and synaptic loss partially mediated the relationship between amyloid deposition and global cognition. With further research, modulating mGluR5 availability might be a potential therapeutic strategy for improving synaptic function in AD.

Abundant pleiotropy across neuroimaging modalities identified through a multivariate genome-wide association study

Genetic pleiotropy is abundant across spatially distributed brain characteristics derived from one neuroimaging modality (e.g. structural, functional or diffusion magnetic resonance imaging [MRI]). A better understanding of pleiotropy across modalities could inform us on the integration of brain function, micro- and macrostructure. Here we show extensive genetic overlap across neuroimaging modalities at a locus and gene level in the UK Biobank (N = 34,029) and ABCD Study (N = 8607). When jointly analysing phenotypes derived from structural, functional and diffusion MRI in a genome-wide association study (GWAS) with the Multivariate Omnibus Statistical Test (MOSTest), we boost the discovery of loci and genes beyond previously identified effects for each modality individually. Cross-modality genes are involved in fundamental biological processes and predominantly expressed during prenatal brain development. We additionally boost prediction of psychiatric disorders by conditioning independent GWAS on our multimodal multivariate GWAS. These findings shed light on the shared genetic mechanisms underlying variation in brain morphology, functional connectivity, and tissue composition.

Measures of resting-state brain network segregation and integration vary in relation to data quantity: implications for within and between subject comparisons of functional brain network organization.

Measures of functional brain network segregation and integration vary with an individual's age, cognitive ability, and health status. Based on these relationships, these measures are frequently examined to study and quantify large-scale patterns of network organization in both basic and applied research settings. However, there is limited information on the stability and reliability of the network measures as applied to functional time-series; these measurement properties are critical to understand if the measures are to be used for individualized characterization of brain networks. We examine measurement reliability using several human datasets (Midnight Scan Club and Human Connectome Project [both Young Adult and Aging]). These datasets include participants with multiple scanning sessions, and collectively include individuals spanning a broad age range of the adult lifespan. The measurement and reliability of measures of resting-state network segregation and integration vary in relation to data quantity for a given participant's scan session; notably, both properties asymptote when estimated using adequate amounts of clean data. We demonstrate how this source of variability can systematically bias interpretation of differences and changes in brain network organization if appropriate safeguards are not included. These observations have important implications for cross-sectional, longitudinal, and interventional comparisons of functional brain network organization.

Metabotropic glutamate receptor 5 (mGluR5) is associated with neurodegeneration and amyloid deposition in Alzheimer’s disease: A [18F]PSS232 PET/MRI study

BackgroundMetabotropic glutamate receptor 5 (mGluR5) is involved in regulating integrative brain function and synaptic transmission. Aberrant mGluR5 signaling and relevant synaptic failure play a key role in the initial pathophysiological mechanism of Alzheimer’s disease (AD). The study aims to investigate the association between mGluR5 availability and AD’s biomarkers and cognitive function.MethodsWe examined 35 individuals with mGluR5 tracer [18F]PSS232 to assess mGluR5 availability, and with [18F]Florbetapir PET to assess global amyloid deposition, and [18F]FDG PET to assess glucose metabolism. The plasma neurofilament light (NfL) and p-tau181 levels in a subset of individuals were measured (n = 27). The difference in mGluR5 availability between the AD and normal control (NC) groups was explored. The associations of mGluR5 availability with amyloid deposition, glucose metabolism, gray matter volume (GMV), neuropsychological assessment scores, and plasma biomarkers were analyzed.ResultsThe mGluR5 availability was significantly reduced in AD patients’ hippocampus and parahippocampal gyrus compared to NCs. Global amyloid deposition was positively associated with mGluR5 availability in the AD group and reversely associated in the NC group. The mGluR5 availability was positively correlated with regional glucose metabolism in the overall and stratified analyses. The availability of mGluR5 in the hippocampus and parahippocampal gyrus demonstrated a strong relationship with the GMV of the medial temporal lobe, plasma p-tau181 or NfL levels, and global cognitive performance.Conclusions[18F]PSS232 PET can quantify the changes of mGluR5 availability in the progression of AD. mGluR5 availability correlated not only with neuropathological biomarkers of AD but also with neurodegenerative biomarkers and cognitive performance. mGluR5 may be a novel neurodegenerative biomarker, and whether mGluR5 could be a potential therapeutic target for AD needs to be further studied.

Magnetic resonance imaging and functional constipation

With the rapid development of society, the incidence of functional constipation (FC) is steadily increasing annually. As it poses an elevated risk for various physical and neuropsychiatric illnesses, the occurrence and development mechanisms of FC have garnered escalating attention from researchers. Accumulating evidence from studies using magnetic resonance imaging (MRI) suggests that FC is associated with alternations in brain function and structure, particularly within brain regions and networks involved in emotion regulation, motor control, somatic sensation, and self-reference. Specifically, significant differences in baseline brain activity and functional connectivity integrity exist between patients with FC and healthy controls. Patients with FC exhibit abnormal cortical morphometry, a lower gray/white matter volume, and impaired white matter integrity. These changes correlate with somatic symptoms, such as the difficulty level of defecation and the sensation of incomplete evacuation. Differences between patients with anxiety/depressive disorders (FCAD) and those without such disorders (FCNAD) underscore the pivotal role of psychiatric factors in FC development. In addition, studies have verified that female patients experience decreased emotional regulation, contributing to a higher prevalence of FC and more severe constipation symptoms than their male counterparts. This paper provides a comprehensive literature review, drawing upon existing MRI studies to explore the various brain abnormalities evident in patients with FC. Through the analysis of these studies, our aim is to shed light on the underlying neural mechanisms and offer valuable insights into the development of novel and effective treatments for FC.

Lifestyle activities contribute to cognitive reserve in mid‐life, independently of education, in cognitively healthy middle‐aged individuals at risk for late‐life Alzheimer’s disease

AbstractBackgroundIt is now acknowledged that Alzheimer’s Disease (AD) processes are present decades before the onset of clinical symptoms, but it remains unknown whether lifestyle factors can protect against these early AD processes in mid‐life. Intellectually, physically, and socially stimulating lifestyle activities are associated with maintenance of late‐life cognitive abilities (Chan et al., 2018), and lower cognitive impairment in AD (Livingston et al., 2020). We asked whether such activities contribute to cognitive reserve (CR) from mid‐life, in cognitively healthy individuals who are at risk for late‐life AD.MethodMiddle‐aged individuals (aged 40‐59 years, mean = 52 years) from the PREVENT Dementia study (www.preventdementia.co.uk) were assessed at baseline (N = 210, 62/148 male/female) and two‐year follow‐up (N = 188, 55/133 male/female), with cognitive ability (multidomain battery) and brain health (total grey matter volume, functional brain network segregation) measures. Mid‐life activities were measured using the Lifetime of Experiences Questionnaire, which comprises occupational as well as intellectually, physically, and socially stimulating leisure activities. Dementia risk was assessed with the Cardiovascular Risk Factors, Aging, and Dementia (CAIDE) score.ResultMultivariable linear regression showed that intellectual, physical, and social activities undertaken in mid‐life made a unique contribution to episodic and relational memory in mid‐life, independent of occupation and CAIDE at baseline (β (se) = 0.04 (0.02), p = 0.02, Figure 1a) and follow‐up (β (se) = 0.07 (0.02), p = 0.002, Figure 1b). Furthermore, these activities moderated the relationship between cognitive ability and brain health at follow‐up (β (se) = 3.47 (1.40), p = 0.01), with verbal and visuospatial functions, and short‐term (conjunctive) memory of people with higher activity levels less dependent on their brain functional integrity (Figure 2), consistent with the concept of CR (Brayne et al., 2010). Such a moderation by these mid‐life activities was more prominent in individuals with higher CAIDE scores (β (se) = 4.28 (1.83), p = 0.02, Figure 3).ConclusionThese findings suggest that modifiable lifestyle activities contribute uniquely to CR and may offset cognitive decrements due to AD risk in mid‐life. They support the targeting of modifiable lifestyle activities for the prevention of Alzheimer’s disease.

Deficits in brain default mode network connectivity mediate the relationship between poor sleep quality and anxiety severity.

Chronic insomnia disorder (CID) is a prevalent sleep disorder that frequently cooccurs with anxiety. The association between insomnia and anxiety has been established; however, the neurobiological basis of this relationship remains unclear. This study aimed to investigate the neural markers of CID patients with and without anxiety and to determine whether specific neural connectivity mediates the relationship between insomnia and anxiety. This study included 180 participants, comprising CID patients with anxiety (CID-A), CID patients without anxiety (CID-NA), and good sleep controls. All participants completed self-reported measures of sleep quality and anxiety severity and underwent functional magnetic resonance imaging. Brain functional integration was measured using functional connectivity density (FCD) and resting-state functional connectivity (rsFC). Correlation and mediation analyses were used to examine the relationships among brain connectivity, sleep quality, and anxiety severity. The CID-NA and CID-A groups showed decreased local FCD in the medial prefrontal cortex (mPFC) and disrupted rsFC between the precuneus and other brain regions. Only the CID-A group exhibited altered long-range FCD in the precuneus and the rsFC between the anterior default mode network (DMN, e.g. mPFC) and posterior DMN (e.g. precuneus). Mediation analysis revealed DMN dysconnectivity underlying the association between poor sleep quality and anxiety symptoms. This study identified shared and distinct brain circuit disruptions in the CID-NA and CID-A groups, with deficits in DMN connectivity as a potential neural mechanism through which disrupted sleep augments anxiety. These findings may facilitate the development of personalized therapies for insomnia and associated anxiety problems.

Alterations of dynamic and static brain functional activities and integration in stroke patients

ObjectiveThe study aimed to investigate the comprehensive characteristics of brain functional activity and integration in patients with subcortical stroke using dynamic and static analysis methods and to examine whether alterations in brain functional activity and integration were associated with clinical symptoms of patients.MethodsDynamic amplitude of low-frequency fluctuation (dALFF), static amplitude of low-frequency fluctuation (sALFF), dynamic degree centrality (dDC), and static degree centrality (sDC) were calculated for 19 patients with right subcortical stroke, 16 patients with left subcortical stroke, and 25 healthy controls (HC). Furthermore, correlation analysis was performed to investigate the relationships between changes in brain functional measurements of patients and clinical variables.ResultsGroup comparison results showed that significantly decreased dALFF in the left angular (ANG_L) and right inferior parietal gyrus (IPG_R), decreased sALFF in the left precuneus (PCUN_L), and decreased sDC in the left crus II of cerebellar hemisphere (CERCRU2_L) and IPG_R, while significantly increased sDC in the right lobule X of cerebellar hemisphere (CER10_R) were detected in patients with right subcortical stroke relative to HC. Patients with left subcortical stroke showed significantly decreased sALFF in the left precuneus (PCUN_L) but increased sDC in the right hippocampus (HIP_R) compared with HC. Additionally, the altered sDC values in the CER10_R of patients with right subcortical stroke and in the HIP_R of patients with left subcortical stroke were associated with the severity of stroke and lower extremities motor function. A correlation was also found between the altered sALFF values in the PCUN_L of patients with left subcortical stroke and lower extremities motor function.ConclusionThese findings suggest that time-varying brain activity analysis may supply complementary information for static brain activity analysis. Dynamic and static brain functional activity and integration analysis may contribute to a more comprehensive understanding of the underlying neuropathology of dysfunction in stroke patients.

A neural mechanism of cognitive reserve: The case of bilingualism

Cognitive Reserve (CR) refers to the preservation of cognitive function in the face of age- or disease-related neuroanatomical decline. While bilingualism has been shown to contribute to CR, the extent to which, and what particular aspect of, second language experience contributes to CR are debated, and the underlying neural mechanism(s) unknown. Intrinsic functional connectivity reflects experience-dependent neuroplasticity that occurs across timescales ranging from minutes to decades, and may be a neural mechanism underlying CR. To test this hypothesis, we used voxel-based morphometry and resting-state functional connectivity analyses of MRI data to compare structural and functional brain integrity between monolingual and bilingual older adults, matched on cognitive performance, and across levels of second language proficiency measured as a continuous variable. Bilingualism, and degree of second language proficiency specifically, were associated with lower gray matter integrity in a hub of the default mode network – a region that is particularly vulnerable to decline in aging and dementia – but preserved intrinsic functional network organization. Bilingualism moderated the association between neuroanatomical differences and cognitive decline, such that lower gray matter integrity was associated with lower executive function in monolinguals, but not bilinguals. Intrinsic functional network integrity predicted executive function when controlling for group differences in gray matter integrity and language status. Our findings confirm that lifelong bilingualism is a CR factor, as bilingual older adults performed just as well as their monolingual peers on tasks of executive function, despite showing signs of more advanced neuroanatomical aging, and that this is a consequence of preserved intrinsic functional network organization.

Standardization of structural and functional brain integration in cannabis users

Standardization of structural and functional brain integration in cannabis users

Acupuncture Alters Brain's Dynamic Functional Network Connectivity in Stroke Patients with Motor Dysfunction: A Randomised Controlled Neuroimaging Trial.

Neuroimaging studies have confirmed that acupuncture can promote static functional reorganization in poststroke patients with motor dysfunction. But its effect on dynamic brain networks remains unclear. This study is aimed at investigating how acupuncture affected the brain's dynamic functional network connectivity (dFNC) after ischemic stroke. We conducted a single-center, randomised controlled neuroimaging study in ischemic stroke patients. A total of 53 patients were randomly divided into the true acupoint treatment group (TATG) and the sham acupoint treatment group (SATG) at a ratio of 2 : 1. Clinical assessments and magnetic resonance imaging (MRI) scans were performed on subjects before and after treatment. We used dFNC analysis to estimate distinct dynamic connectivity states. Then, the temporal properties and strength of functional connectivity (FC) matrix were compared within and between the two groups. The correlation analysis between dynamic characteristics and clinical scales was also calculated. All functional network connectivity (FNC) matrices were clustered into 3 connectivity states. After treatment, the TATG group showed a reduced mean dwell time and found attenuated FC between the sensorimotor network (SMN) and the frontoparietal network (FPN) in state 3, which was a sparsely connected state. The FC between the dorsal attention network (DAN) and the default mode network (DMN) was higher after treatment in the TATG group in state 1, which was a relative segregated state. The SATG group preferred to increase the mean dwell time and FC within FPN in state 2, which displayed a local tightly connected state. In addition, we found that the FC value increased between DAN and right frontoparietal network (RFPN) in state 1 in the TATG group after treatment compared to the SATG group. Correlation analyses before treatment showed that the Fugl-Meyer Assessment (FMA) lower score was negatively correlated with the mean dwell time in state 3. FMA score showed positive correlation with FC in RFPN-SMN in state 3. FMA-lower score was positively correlated with FC in DAN-DMN and DAN-RFPN in state 1. Acupuncture has the potential to modulate abnormal temporal properties and promote the balance of separation and integration of brain function. True acupoint stimulation may have a more positive effect on regulating the brain's dynamic function. Clinical Trial Registration. This trial is registered with Chinese Clinical Trials Registry (ChiCTR1800016263).

Cognition’s dependence on functional network integrity with age is conditional on structural network integrity

Maintaining good cognitive function is crucial for well-being across the lifespan. We proposed that the degree of cognitive maintenance is determined by the functional interactions within and between large-scale brain networks. Such connectivity can be represented by the white matter architecture of structural brain networks that shape intrinsic neuronal activity into integrated and distributed functional networks. We explored how the function-structure connectivity convergence, and the divergence of functional connectivity from structural connectivity, contribute to the maintenance of cognitive function across the adult lifespan. Multivariate analyses were used to investigate the relationship between function-structure connectivity convergence and divergence with multivariate cognitive profiles, respectively. Cognitive function was increasingly dependent on function-structure connectivity convergence as age increased. The dependency of cognitive function on connectivity was particularly strong for high-order cortical networks and subcortical networks. The results suggest that brain functional network integrity sustains cognitive functions in old age, as a function of the integrity of the brain’s structural connectivity.

Copper homeostasis and the ubiquitin proteasome system.

Copper is involved in many physiological pathways and important biological processes as a cofactor of several copper-dependent enzymes. Given the requirement for copper and its potential toxicity, intracellular copper levels are tightly controlled. Disturbances of human copper homeostasis are characterized by disorders of copper overload (Wilson's disease) or copper deficiency (Menkes disease). The maintenance of cellular copper levels involves numerous copper transporters and copper chaperones. Recently, accumulating evidence has revealed that components of the ubiquitin proteasome system (UPS) participate in the posttranslational regulation of these proteins, suggesting that they might play a role in maintaining copper homeostasis. Cellular copper levels could also affect the activity of the UPS, indicating that copper homeostasis and the UPS are interdependent. Copper homeostasis and the UPS are essential to the integrity of normal brain function and while separate links between neurodegenerative diseases and UPS inhibition/copper dyshomeostasis have been extensively reported, there is growing evidence that these two networks might contribute synergistically to the occurrence of neurodegenerative diseases. Here, we review the role of copper and the UPS in the development of Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis, and discuss the genetic interactions between copper transporters/chaperones and components of the UPS.

Cognitive and neuroimaging outcomes in individuals with benign and low-grade brain tumours receiving radiotherapy: a protocol for a prospective cohort study

IntroductionRadiation-induced cognitive decline (RICD) occurs in 50%–90% of adult patients 6 months post-treatment. In patients with low-grade and benign tumours with long expected survival, this is of paramount importance. Despite...

A neuroergonomic approach to assessing motor performance in stroke patients using fNIRS and behavioral data

Stroke is characterized by high morbidity and disability, and proposing effective methods for assessing and designing rehabilitation products is an attractive topic in current research. In this study, a hand function rehabilitation aid was developed for stroke patients. Ten stroke patients and 20 healthy older people as a control group were recruited to perform a 600 s task after a 600 s resting by gripping a stick while clicking on a flashing light in an electronic insert in sequence according to a pattern. The functional near-infrared spectroscopy (fNIRS) and behavioral data were collected during their rehabilitation training. Brain function was analyzed using three indicators, namely brain area activation, functional connectivity and effective connectivity, while behavioral performance was analyzed using ten indicators, such as velocity and acceleration, and correlations were made between both. Followed by proposing a quantitative assessment method based on the fusion of multiple data sources. The results showed that the developed rehabilitation tool could effectively stimulate the patient's brain and help recover their cognitive and behavioral capacities. The scientific validity of the proposed assessment approach was further confirmed by contrasting the data results of the stroke group with those of the healthy elderly group. This study has integrated brain function and behavioral data, providing a practical quantitative evaluation method of product ergonomics and data-driven product design concepts for stroke patients.

DUAL-TASK TRAINING FOR IMPROVING COGNITIVE-MOTOR INTERFERENCE

Abstract Dr. Bhatt will discuss the differences in types of cognitive motor interference patterns experienced for different tasks (gaitand volitional versus reactive balance) in cognitively intact versus people with mild cognitive impairment. She will discuss the effectiveness of dual-task training and exergaming on gait, volitional and reactive balance control in older adults with mild cognitive impairment. After 4 weeks of such training, the results showed beneficial effects on improving volitional based performance when performed with a cognitive task (i.e., spatial memory and executive function) and had significant improvement in NIH toolbox (cognitive- increased working memory, episodic memory and executive function, and motor-increased gait speed). However, its positive effects on dual task reactive balance control were limited. Additionally, the speaker will go on to discuss the associations of balance control deficits in mild cognitive impairment with neural correlates (structural and functional brain integrity) to understand the attributing factors to increased fall risk in people with mild cognitive impairment.

C‐reactive protein (CRP) blood concentrations associate with reduced global system segregation in middle‐aged individuals

AbstractBackgroundHigh concentrations of circulating C‐reactive protein (CRP) have been related to poorer cognition in adults (Lewis et al. Age Ageing. 2021;50:2199). Within the Lifebrain consortium (Walhovd et al. Eur Psychiatry. 2018;50:47), we recently reported overall lifespan associations between increased CRP and smaller hippocampal (HPC) volumes, albeit these could not be observed in one subsample of middle‐aged individuals (Wang et al. Brain Behav Immun. 2022;100:243). Here we hypothesized that functional brain integrity measures would be sensitive to predict CRP levels in this group. We focused on global system segregation (SyS) a graph theory‐based metric which quantifies the extent to which major functional networks are segregated from each other.MethodWe included 336 volunteers (mean age 53.8; SD: 7.1; 47.9% women) from the Barcelona Brain Health Initiative (Cattaneo et al. Front Aging Neurosci. 2018;10:321). High‐sensitive CRP (hsCRP) concentrations were determined through dry blood samples and log10 transformed (Wang et al. Brain Behav Immun. 2022;100:243). Adjusted HPC volumes were estimated from T1‐wheigthed 3T MRI acquisitions (Raz et al. Cereb Cortex 2005;15:1676). SyS values were calculated (Ewers et al. Brain. 2021;144:2176) from 100 nodes defined by the Schaefer‐Yeo atlas (Fig 1a). Multiple linear regression investigated the associations between age, gender, cognitive function (MMSE and episodic memory), HPC volumes, APOE status and SyS as predictor variables and hs‐CRP as the dependent measure.ResultIn the adjusted model only SyS (β= ‐0.56, p<0.05) and APOE (β= ‐0.21, p=0.003) predicted hsCRP concentrations. Global SyS was negatively related to hsCRP (Fig 1b). As in Wang et al (2022), APOE E4 carriers (N=71; mean:‐0.43; SD=0.62) exhibited lower CRP circulating levels than non‐E4 bearers (N=265; mean: ‐0.20; SD=0.51; t=3.23, p<0.001), however there were no differences in SyS according to APOE genotypes (t=0.95, p=0.34).Conclusionhs‐CRP blood concentrations were predicted by global segregation of functional networks in absence of HPC volume or cognitive status effects. As such, blood derived hsCRP levels may represent an early indicator of middle‐age individual variations in a measure recently reported to predict future cognitive decline (Chan et al. Nat Aging 2021;1:1053) and represent a cognitive resilience mechanism in the face of AD pathology (Ewers et al. Brain. 2021;144:2176).

Ginkgolides and bilobalide for treatment of Alzheimer's disease and COVID-19: potential mechanisms of action.

Alzheimer's disease (AD) is an irreversible degenerative illness of the central nervous system with characteristic histological alterations, known as amyloid plaques and neurofibrillary tangles (NFT). Aggregation of plaques and tangles in the brain induces neurotoxicity and synaptic dysfunction, eventually contributing to neuronal cell death and neurodegeneration. Recent studies have revealed that COVID-19 has a great impact on the development of AD, directly or indirectly, by facilitating the accumulation of amyloid plaques, causing altered functional brain integrity or increasing the phosphorylation rate of tau protein. As two important bioactive components of Ginkgo biloba extract (GbE), ginkgolides and bilobalide (BB) have been reported to show neuroprotective effects in AD via multiple mechanisms such as anti-excitotoxicity, anti-inflammatory and anti-oxidative activities. Intriguingly, ginkgolides and BB also seem to demonstrate antiviral properties against COVID-19 by inhibiting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) main protease. Herein, we review studies on the neuroprotective and antiviral mechanisms of ginkgolides and bilobalide, as well as their therapeutic potential against AD and COVID-19.

Neural efficiency and proficiency adaptation of effective connectivity corresponding to early and advanced skill levels in athletes of racket sports.

This study explored how the neural efficiency and proficiency worked in athletes with different skill levels from the perspective of effective connectivity brain network in resting state. The deconvolved conditioned Granger causality (GC) analysis was applied to functional magnetic resonance imaging (fMRI) data of 35 elite athletes (EAs) and 42 student-athletes (SAs) of racket sports as well as 39 normal controls (NCs), to obtain the voxel-wised hemodynamic response function (HRF) parameters representing the functional segregation and effective connectivity representing the functional integration. The results showed decreased time-to-peak of HRF in the visual attention brain regions in the two athlete groups compared with NC and decreased response height in the advanced motor control brain regions in EA comparing to the nonelite groups, suggesting the neural efficiency represented by the regional HRF was different in early and advanced skill levels. GC analysis demonstrated that the GC values within the middle occipital gyrus had a linear trend from negative to positive, suggesting a stepwise "neural proficiency" of the effective connectivity from NC to SA then to EA. The GC values of the inter-lobe circuits in EA had the trend to regress to NC levels, in agreement with the neural efficiency of these circuits in EA. Further feature selection approach suggested the important role of the cerebral-brainstem GC circuit for discriminating EA. Our findings gave new insight into the complementary neural mechanisms in brain functional segregation and integration, which was associated with early and advanced skill levels in athletes of racket sports.