Search Results (157)

Resting-state functional connectivity (rsFC) provides insight into the intrinsic organization of brain networks and is increasingly recognized as a sensitive marker of age-related neural changes. Functional near-infrared spectroscopy (fNIRS) offers a portable and cost-effective approach to measuring rsFC, including in naturalistic settings. However, its sensitivity to age-related alterations in network topology remains poorly characterized. Here, we applied graph-based analysis to resting-state fNIRS data from 57 healthy participants, including 26 young adults (YA, 18–30 years) and 31 older adults (OA, 50–77 years). We observed that older adults exhibited a marked attenuation of low-frequency oscillation (LFO) power across all hemoglobin contrasts, corresponding to a 5–6-fold reduction in spectral power. In addition, network analysis revealed altered topological organization under matched sparsity conditions, characterized by reduced degree heterogeneity and increased segregation in older adults, with the strongest differences observed in the default mode (DMN), auditory, and frontoparietal control (FPC) networks. Network visualizations further indicated a shift toward more right-lateralized and posterior hub organization in older adults. Together, the coexistence of reduced oscillatory power and increased connectivity suggests that fNIRS-derived rsFC reflects combined neural and non-neural hemodynamic influences, including increased coherence arising from age-related vascular and systemic physiological processes. Overall, our findings demonstrate that fNIRS is sensitive to age-related changes in large-scale hemodynamic network organization. At the same time, sensitivity to non-neural hemodynamics highlights the need for cautious interpretation, but it may provide complementary, clinically relevant signatures of aging-related changes. Full article

Objective: This study aimed to investigate the functional connectivity (FC) of three amygdala subregions—the laterobasal amygdala (LBA), centromedial amygdala (CMA), and superficial amygdala (SFA)—with large-scale brain networks in individuals with schizophrenia (SCZ) compared to healthy controls (HC). Methodology: Resting-state functional magnetic resonance imaging (rs-fMRI) data were obtained from 100 participants (50 SCZ, 50 HC) with balanced age and gender distributions. FC between amygdala subregions and target functional networks was assessed using a region-of-interest (ROI)-to-ROI approach implemented in the CONN toolbox. Result: Connectivity patterns of the LBA, CMA, and SFA differed between SCZ and HC groups. After false discovery rate (FDR) correction (p < 0.05), SCZ patients exhibited significantly increased FC between the left CMA and both the default mode network (DMN) and the visual network (VN). In contrast, decreased FC was observed between the right LBA and the sensorimotor network (SMN) in SCZ compared with HC. Conclusions: These findings reveal novel FC alterations linking amygdala subregions with large-scale networks in schizophrenia. The results underscore the importance of examining the amygdala as distinct functional subregions rather than as a single structure, offering new insights into the neural mechanisms underlying SCZ. Full article

Background: Although smartphone usage is inevitable and convenient in recent days, numerous potential problems due to excessive smartphone use (ESU) have been highlighted. With the rising concern about ESU, the focus on exploring the relationship between ESU and personality traits and their neural correlations also increased; however, studies that explore these factors simultaneously are lacking. Objective: This study investigated whether altered resting state functional connectivity (rsFC) is related to personality traits in adolescents exhibiting ESU compared to healthy controls (HCs). Methods: Thirty-one adolescents exhibiting ESU and 31 HCs (62 adolescents) aged 12–18 years were included in this study. Seed-to-voxel connectivity analysis was used to examine group differences in rsFC in the middle cingulate cortex (MCC) and insula, key parts of the salience network, in relation to personality traits. Results: Adolescents exhibiting ESU showed trends toward low persistence and high harm avoidance in terms of personality traits. Additionally, they exhibited enhanced rsFC between the MCC and insula but reduced rsFC between the precentral and postcentral gyri compared with HCs. Notably, increased rsFC between the MCC and insula in the ESU group was negatively correlated with low persistence. Conclusions: ESU was associated with low persistence at the uncorrected threshold in terms of personality traits and involved in neuro-functional alterations between the key hubs of the salience network, MCC, insula, and several other brain regions. These findings may provide a neurobiological basis for intervention targeting behavioral addiction in youth. Accordingly, adolescents with low persistence may need tailored education on appropriate and controlled use of smartphones and internet-based technologies. Full article

The correct course of DNA replication is crucial to maintaining the integrity of the genome. Any abnormality in this process inevitably leads to replication stress (RS). Hydroxyurea (HU) is a replication stressor widely used to inhibit DNA biosynthesis by depleting the deoxyribonucleoside triphosphate (dNTP) pool. The aim of the study was to examine how the 24-, 48-, and 72 h exposures to 0.75 mM HU affect the localization of fibrillarin (FBL; a highly conserved nucleolar protein and the component of Cajal bodies) and the amount of rRNA transcripts (detected using 5-ethynyl uridine; 5-EU), in root meristem cells of Allium cepa. The consequence of prolonged RS was initially (after 24 h of incubation in HU) a 2-fold increase in 5-EU incorporation into the nucleolus, then (after 48- and 72 h incubations) followed by a gradual decrease in rRNA transcription to a level similar to that of the control. In interphase and in early prophase, both in the control material and during successive periods of incubation of root meristems in HU, the immunofluorescence of FBL accumulated in the fibrillar centers (FCs) of the nucleoli, in the dense fibrillar components (DFC), and in the granular components (GC). In some HU-treated metaphase cells, FBL was localized around the telomeres of the chromosomes, while in telophase, it was found in the fragmented chromosomes. In addition, an increase in the number of Cajal bodies (CBs) was observed during subsequent incubation periods with HU. After 48 and 72 h of treatment with HU, the number of CBs was found to be almost twice that observed in the control series. CBs disappeared in prophase and reappeared in interphase. These results suggest that depending on the duration of RS, changes in the level of rRNA transcription and in the abundance of CBs may correlate with the production of RNP and ribosome biogenesis. Full article

Antibodies are produced by cells of the adaptive immune response and recognize epitopes of microbial structures with high affinity and specificity. Antibodies are recognized by Fc fragment receptors (FcRs) found on the surface of phagocytic cells (neutrophils, monocytes, macrophages) and NK cells, among others. Hence, antibodies link the adaptive immune response with the innate immune response. The functions of antibodies are related to the N-glycosylation profile of these proteins. In this review, we describe how N-glycosylation of the Fc fragment of the different antibody classes is carried out, and which oligosaccharides are most commonly found in these antibodies. Subsequently, we summarize the biological effects of N-glycosylation of antibodies: on the binding of antibodies to FcRs (which affects various functions, such as antibody-dependent cellular cytotoxicity, antibody-dependent phagocytosis, and the production of pro- or anti-inflammatory chemokines and cytokines), on the ability of antibodies to activate complement and on the ability of some antibodies to directly neutralize the adhesion of bacteria and viruses to host cells (independently of Fab recognition). We describe how the N-glycosylation profile of antibodies is modified during certain infections (such as tuberculosis, COVID-19, influenza and dengue) and in response to vaccination, and the potential use of this profile to identify the stage and severity of an infection. Finally, we review the importance of N-glycosylation for the pharmacokinetic, pharmacodynamic and safety profiles of therapeutic monoclonal antibodies. Full article

Objectives. Identity disturbance and instability in Borderline Personality Disorder (BPD) are associated with impairments in the integration of emotional autobiographical memory (EAM). At the neurophysiological level, it has been suggested that EAM dysfunction may be linked with functional connectivity (FC) alterations of the salience network (SN). Despite this, evidence in adolescents with BPD remains scarce, especially under task-related conditions. Therefore, we investigated SN electroencephalography (EEG) FC in adolescents with BPD during the resting-state condition (RS) and during two EAM tasks (i.e., happiness- and fear-related). Methods. A total of 24 female adolescents with BPD and 15 healthy controls underwent RS and task-related EEG recording. All participants were also assessed for BPD and related clinical dimensions. EEG FC analyses in the SN were performed using exact Low-Resolution Brain Electromagnetic Tomography (eLORETA) software. Results. Compared to controls, BPD patients exhibited reduced theta SN connectivity during RS. This hypo-connectivity pattern was positively correlated with all BPD-related dimensions (i.e., emotional dysregulation, impulsiveness, dissociative symptoms, and childhood trauma). Furthermore, compared to the RS, during the listening of fear-related memories, BPD patients showed an increase in delta SN connectivity. This hyper-connectivity pattern was negatively correlated with the self-reported vividness of recall. Conclusions. While decreased SN theta connectivity may be a common neural marker of traumatic disintegration, increased SN delta connectivity may indicate a neural correlate of suppression/avoidance of negative memories. Full article

Background: Resting-state functional connectivity (RSFC) is widely used to identify abnormal brain function associated with depression. Resting-state functional magnetic resonance imaging (fMRI) scans have many potential confounds, and task-based FC might provide complementary information leading to better insight on brain function. Methods: We used MATLAB’s (version 2024b) CONN toolbox (version 22a) to evaluate FC in 40 adults with and without major depressive disorder (MDD) (n_MDD = 23, n_HC = 17). fMRI acquisition was performed while participants were at rest and while performing the Selves Task, an individualized goal priming task. Seed-based analyses were performed using two seeds: medial prefrontal cortex (mPFC) and left hippocampus. Results: Both groups showed strong positive RSFC between the mPFC and other DMN regions, including the anterior cingulate cortex and precuneus, which had more focal positive FC to the mPFC during the task in both groups. Additionally, the MDD group had significantly lower RSFC between the mPFC and several regions, including the right inferior temporal gyrus. The left hippocampus seed-based analysis revealed a pattern of hypoconnectivity to multiple brain regions in MDD, including the cerebellum, which was present at rest and during the task. Conclusions: Our results indicated multiple FC differences between adults with and without MDD, as well as distinct FC patterns and contrast results in resting state and task-based analyses, including differential FC between mPFC–cerebellum and hippocampus–cerebellum. These results emphasize that resting-state and task-based fMRI capture distinct patterns of brain connectivity. Further investigation into combining resting-state and task-based FC could inform future neuroimaging research. Full article

Insights into motor cortex remodeling may enable the development of more effective rehabilitation strategies during the acute phase. We aim to assess the affected and unaffected motor/premotor/somatosensory cortex resting state functional connectivity (RSFC) and reactivity with continuous wave functional near-infrared spectroscopy (cw-fNIRS) in patients with ICH compared to age, sex, and comorbidity-matched subjects. We enrolled patients with acute–subacute hemispheric ICH (n = 37; two were excluded due to artifacts) and grouped them according to the side (right and left) of the stroke. Matched participants or patients with recent transient ischemic attack were enrolled as control subjects for the study (n = 44; five were excluded due to artifacts). RSFC was assessed in both affected and unaffected hemispheres by group-level seed-based (primary motor cortex, priMC) correlation analysis. FT-associated relative oxyhemoglobin (ΔHbO) changes were analyzed in affected and unaffected hemispheres with generalized linear model regression. In left hemispheric ICH, the resting state coherence between the affected priMC and the affected premotor cortex (preMC) increased (β = 0.83, 95% CI = 0.19, 1.47, p = 0.01). In contrast, in right hemispheric ICH, the coherence between the unaffected priMC and the affected preMC decreased (β = −0.6, 95% CI = −1.12, −0.09, p = 0.02). In the left hemispheric ICH, the left-hand FT was associated with increased ΔHbO over the affected preMC (β = 0.01, 95% CI = 0.003, 0.02, p = 0.01). In contrast, in right hemispheric ICH, the left-hand FT was associated with increased ΔHbO over the unaffected preMC (β = 0.02, 95% CI = 0.006, 0.04, p = 0.01). Left hemispheric preMC may be involved in motor cortex reorganization in acute ICH in either hemisphere. Further studies may be required to assess longitudinal changes in motor cortex reorganization to inform acute motor rehabilitation. Full article

Antibodies are a cornerstone of the adaptive immune response, serving as key defenders against viral infections; however, they can also act as a double-edged sword, contributing to immune-mediated pathologies. This review advances a “Yin-Yang” framework to integrate the dual activities of antibodies. The protective ‘Yin’ functions are driven by high-affinity antibodies generated through processes like somatic hypermutation and class-switch recombination. These antibodies execute viral neutralization, activate the complement system, and engage Fc receptors (FcRs) to drive antibody-dependent cellular cytotoxicity (ADCC) and phagocytosis. These mechanisms form the immunological basis of effective vaccines, which aim to elicit durable and functionally specialized antibody isotypes like IgG and mucosal IgA. Conversely, the pathogenic ‘Yang’ of the response can be detrimental. This includes antibody-dependent enhancement (ADE) of infection, notably observed with flaviviruses, and the development of autoimmunity through mechanisms like molecular mimicry and bystander activation, which can lead to conditions such as multiple sclerosis and Guillain-Barré Syndrome. The balance between protection and pathology is tipped by a confluence of factors. These include viral evasion strategies like antigenic mutation and glycan shielding, as well as host-based determinants such as genetic polymorphisms in FcRs, immune history, and the gut microbiome. Understanding these molecular determinants informs the rational design of next-generation interventions. Promising strategies, such as Fc-region glyco-engineering and the design of tolerogenic vaccines, aim to selectively promote protective functions while minimizing pathological risks, offering a clear path forward in combating viral threats. Full article

Background/Objectives: Neural compensation, in which healthy brain regions take over functions lost due to lesions, is a potential biomarker for functional recovery after stroke. However, previous neuroimaging studies often speculated on neural compensation simply based on greater measures in patients (compared to healthy controls) without demonstrating a more direct link between these measures and the functional recovery. Because taking over the function of a lesion region means taking on a similar role as that lesion region in its functional network, the present study attempted to explore neural compensation based on the similarity of functional connectivity (FC) patterns between a healthy regions and lesion regions. Methods: Seventeen stroke patients (13M4F, 63.2 ± 9.1 y.o.) underwent three resting-state functional MRI (rs-fMRI) sessions during rehabilitation. FC patterns of their lesion regions were derived by lesion network analysis; and these patterns were correlated with healthy FC patterns derived from each brain voxel of 51 healthy subjects (32M19F, 61.0 ± 14.3 y.o.) for the assessment of pattern similarity. Results: We identified five healthy regions showing decreasing FC similarity (29–54%, all corrected p < 0.05, effect size η²: 0.10–0.20) to the lesion network over time. These decreasing similarities were associated with increasing behavioral scores on activities of daily living (ADL, p < 0.001, η² = 0.90), suggesting greater neural compensation at early-stage post-stroke and reduced compensation toward the end of effective rehabilitation. Conclusions: Besides direct FC measures, the present results propose an alternative biomarker of neural compensation in functional recovery from stroke. For sensorimotor recoveries like ADL, this biomarker could be more sensitive than direct measures of lesion connectivity in the motor network. Full article

Olfactory impairment was assessed in akinetic-rigid (PD_AR) and tremor-predominant (PD_T) subtypes of Parkinson’s disease (PD), classified based on motor symptoms. Seventeen PD_AR, fifteen PD_T, and twenty-four cognitively normal (CN) participants completed the University of Pennsylvania Smell Identification Test (UPSIT). Groups were well-matched for age and demographic variables, with cognitive performance statistically controlled. Resting-state fMRI (rs-fMRI) and seed-based functional connectivity (FC) analyses were conducted to characterize olfactory network (ON) connectivity across groups. UPSIT scores were significantly lower in PD_AR compared to PD_T. Consistently, ON FC values were reduced in PD_AR relative to both PD_T and CN. FC of the primary olfactory cortex (POC) significantly differed between CN and the PD subtypes. Furthermore, connectivity in the orbitofrontal cortex and insula showed significant differences between PD_AR and PD_T, as well as between PD_AR and CN. Notably, ON FC between the left hippocampus and the posterior cingulate cortex (PCC) also differed significantly between PD_AR and PD_T. These findings reveal distinct ON FC patterns across PD_AR and PD_T subtypes. Variations in UPSIT scores suggest that motor symptom subtype is associated with olfactory performance. Moreover, ON connectivity closely paralleled the UPSIT scores, reinforcing a neural basis for olfactory deficits in PD. Given the accelerated motor and cognitive decline often observed in the PD_AR, these results support the potential of olfactory impairment as a clinical marker for disease severity. Full article

Background/Objectives: Schizophrenia exhibits symptoms linked to the hippocampus and parahippocampal gyrus. This includes the entorhinal cortex (ERC) and perirhinal cortex (PRC) as anterior parts, along with the posterior segment known as the parahippocampal cortex (PHC). However, recent research has detailed atlases based on cytoarchitectural characteristics and the hippocampus divided into four subregions: cornu ammonis (CA), dentate gyrus (DG), subiculum (SUB), and hippocampal–amygdaloid transition (HATA). This study aimed to explore the functional connectivity (FC) changes between these hippocampal subregions and the parahippocampal gyrus structures (ERC, PRC, and PHC) as well as between hippocampal subregions and various functional brain networks in schizophrenia. Methods: In total, 50 individuals with schizophrenia and 50 matched healthy subjects were examined using resting state functional magnetic resonance imaging (rs-fMRI). Results: The results showed alterations characterized by increases and decreases in the strength of the positive connectivity between the parahippocampal gyrus structures and the four hippocampal subregions when comparing patients with schizophrenia with healthy subjects. Alterations were observed among the hippocampal subregions and functional brain networks, as well as the formation of new connections and absence of connections. Conclusions: There is strong evidence that the different subregions of the hippocampus have unique functions and their connectivity with the parahippocampal cortices and brain networks are affected by schizophrenia. Full article

Fc gamma receptors (FcγRs) control humoral and cellular immune responses and maintain the immune system balance. Functional polymorphisms of FcγRs, whose prevalence was dependent on ethnic origin, were found to be associated with systemic lupus erythematosus (SLE) or kidney injuries in several ethnic groups. We aimed at investigating the association between the functional single-nucleotide polymorphisms (SNPs) of FcγRIIa-H131R (rs1801274), FcγRIIb-I232T (rs1050501), FcγRIIIa-V158F (rs396991) and FcγRIIIb variants (NA1 and NA2) and lupus erythematosus systemic in an indigenous African Caribbean population. We compared the frequencies of the functional SNPs of FCGR2A (FcγRIIa-H131R, rs1801274), FCGR2B (FcγRIIb-I232T, rs1050501), FCGR3A (FcγRIIIa-V158F, rs396991) and FCGR3B variants (FcγRIIIb NA1 and NA2) between lupus and healthy controls in an indigenous African Caribbean population. We highlighted an association between the FCGR3B-NA1/NA1 and FCGR3A-158F alleles and systemic lupus erythematosus, in addition to an association between FCGR2A-131R and lupus nephritis. Furthermore, an increase in the 131R-158V haplotype in lupus nephritis (30.4%) vs. lupus non-nephritis (15.8%) was noticed. Surprisingly, in spite of the high frequency of the FCGR2B-232T allele in our population, our study did not highlight any association of this allele either with SLE or lupus nephritis (a severe and frequent form of SLE). CD72-Hap1, which has been shown to confer resistance to SLE against T232 allele, was not enhanced in the control group. Our results emphasize an association between FCGR2A-131R and lupus nephritis with a distinctive FCGR polymorphism distribution in an indigenous African Caribbean population, confirming the important variation in the FCGR locus depending on ethnic origin. Full article

The hippocampus is one of the brain’s most vulnerable structures to hypoxia, playing a crucial role in memory and spatial navigation. This sensitivity makes it a key region for understanding the effects of hypoxia on brain connectivity. This review examines the effects of both acute and chronic hypoxia on resting-state networks (RSNs) that contribute to hippocampal functional connectivity (FC). Hypoxia, characterized by a reduced oxygen supply to the brain, can result from environmental factors (such as high-altitude exposure) or hypoxia-induced pathological conditions (including obstructive sleep apnea and hypoxic–ischemic encephalopathy). The hippocampus’s susceptibility to hypoxic damage significantly impairs brain connectivity. This review examines through rs-fMRI studies how hypoxia alters hippocampal FC, focusing on its effects on RSNs involved in hippocampal functions, and compares acute and chronic hypoxic states. We seek to determine whether distinct or shared patterns of FC changes exist between acute and chronic hypoxia, and how hypoxia indirectly changes hippocampal FC, given the challenges of studying it in isolation. By addressing these questions, this review aims to deepen our understanding of hypoxia-induced changes in hippocampal FC and provide insights into potential therapeutic strategies to mitigate its effects on cognitive functions. Full article

The biology literature addresses two puzzles: (i) the increase in specific metabolic rate of organs (SOrMR, W/kg of organ) with a decrease in body mass (M_B) of biological species (BS), and (ii) how the organs recognize they are in a smaller or larger body and adjust metabolic rates of the body (${\dot{q}}_B$) accordingly. These puzzles were answered in the author’s earlier work by linking the field of oxygen-deficient combustion (ODC) of fuel particle clouds (FC) in engineering to the field of oxygen-deficient metabolism (ODM) of cell clouds (CC) in biology. The current work extends the ODM hypothesis to predict the whole-body metabolic rates of 114 BS and demonstrates Kleiber’s power law {${\dot{q}}_B = a {M_B}^b$}. The methodology is based on the postulate of Lindstedt and Schaeffer that “150 ton blue whale. and the 2 g Etruscan shrew.. share the same.. biochemical pathways” and involve the following steps: (i) extension of the effectiveness factor relation, expressed in terms of the dimensionless group number G (=Thiele Modulus²), from engineering to the organs of BS, (ii) modification of G as G_OD for the biology literature as a measure of oxygen deficiency (OD), (iii) collection of data on organ and body masses of 116 species and prediction of SOrMR_k of organ k of 114 BS (from 0.0076 kg Shrew to 6650 kg elephant) using only the SOrMR_k and organ masses of two reference species (Shrew, 0.0076 kg: RS-1; Rat Wistar, 0.390 kg: RS-2), (iv) estimation of ${\dot{q}}_B$ for 114 species versus M_B and demonstration of Kleiber’s law with a = 2.962, b = 0.747, and (v) extension of ODM to predict the allometric law for maximal metabolic rate (under exercise, {${\dot{q}}_{B,MMR} = a_{MMR} {M_B}^{b_{MMR}}$}) and validate the approach for MMR by comparing b_MMR with the literature data. A method of detecting hypoxic condition of an organ as a precursor to cancer is suggested for use by medical personnel Full article