Changes In Brain Functional Connectivity Research Articles

Alterations in brain network connectivity and subjective experience induced by psychedelics: a scoping review.

Intense interest surrounds current research on psychedelics, particularly regarding their potential in treating mental health disorders. Various studies suggest a link between the subjective effects produced by psychedelics and their therapeutic efficacy. Neuroimaging evidence indicates an association of changes in brain functional connectivity with the subjective effects of psychedelics. We conducted a review focusing on psychedelics and brain functional connectivity. The review focused on four psychedelic drugs: ayahuasca, psilocybin and LSD, and the entactogen MDMA. We conducted searches in databases of MEDLINE, Embase, APA PsycInfo and Scopus from inception to Jun 2023 by keywords related to functional connectivity and psychedelics. Using the PRISMA framework, we selected 24 articles from an initial pool of 492 for analysis. This scoping review and analysis investigated the effects of psychedelics on subjective experiences and brain functional connectivity in healthy individuals. The studies quantified subjective effects through psychometric scales, revealing significant experiences of altered consciousness, mood elevation, and mystical experiences induced by psychedelics. Neuroimaging results indicated alterations in the functional connectivity of psychedelics, with consistent findings across substances of decreased connectivity within the default mode network and increased sensory and thalamocortical connectivity. Correlations between these neurophysiological changes and subjective experiences were noted, suggesting a brain network basis of the psychedelics' neuropsychological impact. While the result of the review provides a potential neural mechanism of the subjective effects of psychedelics, direct clinical evidence is needed to advance their clinical outcomes. Our research serves as a foundation for further exploration of the therapeutic potential of psychedelics.

Plasma Neurofilament Light Relates to Divergent Default and Salience Network Connectivity in Alzheimer's Disease and Behavioral Variant Frontotemporal Dementia.

Alzheimer's disease (AD) and behavioral variant frontotemporal dementia (bvFTD) show differential vulnerability to large-scale brain functional networks. Plasma neurofilament light (NfL), a promising biomarker of neurodegeneration, has been linked in AD patients to glucose metabolism changes in AD-related regions. However, it is unknown whether plasma NfL would be similarly associated with disease-specific functional connectivity changes in AD and bvFTD. Our study examined the associations between plasma NfL and functional connectivity of the default mode and salience networks in patients with AD and bvFTD. Plasma NfL and neuroimaging data from patients with bvFTD (n = 16) and AD or mild cognitive impairment (n = 38; AD + MCI) were analyzed. Seed-based functional connectivity maps of key regions within the default mode and salience networks were obtained and associated with plasma NfL in these patients. We demonstrated divergent associations between NfL and functional connectivity in AD + MCI and bvFTD patients. Specifically, AD + MCI patients showed lower default mode network functional connectivity with higher plasma NfL, while bvFTD patients showed lower salience network functional connectivity with higher plasma NfL. Further, lower NfL-related default mode network connectivity in AD + MCI patients was associated with lower Montreal Cognitive Assessment scores and higher Clinical Dementia Rating sum-of-boxes scores, although NfL-related salience network connectivity in bvFTD patients was not associated with Neuropsychiatric Inventory Questionnaire scores. Our findings indicate that plasma NfL is differentially associated with brain functional connectivity changes in AD and bvFTD.

Beta Spectral Power During Passive Listening in Preschool Children with Specific Language Impairment

Introduction. Children with Specific Language Impairment (SLI) have difficulties in different speech and language domains. Electrophysiological studies have documented that auditory processing in children with SLI is atypical and probably caused by delayed and abnormal auditory maturation. During the resting state, or different auditory tasks children with SLI show low or high beta spectral power, which could be a clinical correlate for investigating brain rhythms. Methods. The aim of this study was to examine the electrophysiological cortical activity of the beta rhythm while listening to words and nonwords in children with SLI in comparison to typical developing (TD) children. The participants were 50 children with SLI, aged 4 and 5 years old, and 50 age-matched TD children. The children were divided into two subgroups according to age: 1) children 4 years of age; 2) children 5 years of age. Results. The older group differed from the younger group in beta auditory processing, with increased values of beta spectral power in the right frontal, temporal, and parietal regions. In addition, children with SLI have higher beta spectral power than TD children in the bilateral temporal regions. Conclusion. Complex beta auditory activation in TD and SLI children indicate the presence of early changes in functional brain connectivity.

Alterations in spatiotemporal characteristics of dynamic networks in juvenile myoclonic epilepsy.

Juvenile myoclonic epilepsy (JME) is characterized by altered patterns of brain functional connectivity (FC). However, the nature and extent of alterations in the spatiotemporal characteristics of dynamic FC in JME patients remain elusive. Dynamic networks effectively encapsulate temporal variations in brain imaging data, offering insights into brain network abnormalities and contributing to our understanding of the seizure mechanisms and origins. Resting-state functional magnetic resonance imaging (rs-fMRI) data were procured from 37 JME patients and 37 healthy counterparts. Forty-seven network nodes were identified by group-independent component analysis (ICA) to construct the dynamic network. Ultimately, patients' and controls' spatiotemporal characteristics, encompassing temporal clustering and variability, were contrasted at the whole-brain, large-scale network, and regional levels. Our findings reveal a marked reduction in temporal clustering and an elevation in temporal variability in JME patients at the whole-brain echelon. Perturbations were notably pronounced in the default mode network (DMN) and visual network (VN) at the large-scale level. Nodes exhibiting anomalous were predominantly situated within the DMN and VN. Additionally, there was a significant correlation between the severity of JME symptoms and the temporal clustering of the VN. Our findings suggest that excessive temporal changes in brain FC may affect the temporal structure of dynamic brain networks, leading to disturbances in brain function in patients with JME. The DMN and VN play an important role in the dynamics of brain networks in patients, and their abnormal spatiotemporal properties may underlie abnormal brain function in patients with JME in the early stages of the disease.

Altered regional brain activity and functional connectivity in primary intravaginal anejaculation patients revealed by resting-state fMRI.

Ejaculation is regulated by the central nervous system. However, the central pathophysiology of primary intravaginal anejaculation (PIAJ) is unclear. The present study aimed to examine the changes in regional brain activity and functional connectivity underlying PIAJ. A total of 20 PIAJ patients and 16 healthy controls (HCs) were enrolled from September 2020 to September 2022 in the Department of Andrology, Nanjing Drum Tower Hospital (Nanjing, China). Magnetic resonance imaging data were acquired from all participants and then were preprocessed. The measures of fractional amplitude of low-frequency fluctuation (fALFF), regional homogeneity (ReHo), and functional connectivity (FC) were calculated and compared between the groups. PIAJ patients showed increased fALFF values in the left precuneus compared with HCs. Additionally, PIAJ patients showed increased ReHo values in the left precuneus, left postcentral gyrus, left superior occipital gyrus, left calcarine fissure, right precuneus, and right middle temporal gyrus, and decreased ReHo values in the left inferior parietal gyrus, compared with HCs. Finally, brain regions with altered fALFF and ReHo values in PIAJ patients showed increased FC with widespread cortical regions, which included the frontal, parietal, temporal, and occipital regions, compared with HCs. In conclusion, increased regional brain activity in the parietal, temporal, and occipital regions, and increased FC between these brain regions, may be associated with PIAJ occurrence.

Brain functional connectivity correlates of anomalous interaction between sensorily isolated monozygotic twins.

This study examined brain functional connectivity (FC) changes associated with possible anomalous interactions between sensorily isolated monozygotic (MZ) twins. Brain FC was estimated using the Steady State Visual Evoked Potential-Event Related Partial Coherence (SSVEP-ERPC) methodology. Five twin pairs served twice as participants, with an average interval between sessions of 67 days. In each recording session, one twin, the Sender, viewed a randomized set of 50 general images and 50 personally relevant images, while the other twin, the Receiver, viewed a static personally relevant image for the entire duration of the session. Images appeared on the Sender screen for 1.0 s, with the interval between successive images varied randomly between 4.0 and 8.0 s. Receiver FC changes were calculated based on the appearance times of the images as viewed by the Sender. It was hypothesized that anomalous interactions would be indicated by statistically significant Receiver FC changes when those changes are determined using the Sender image appearance times. For each twin serving as Receiver, FC components were separately analyzed for the 50 general and the 50 personal images, yielding 38 observations (19 twin pairs by 2 conditions). The hypothesis was confirmed in that 11 of the 38 observations yielded statistically significant Receiver FC increases or decreases at the p < 0.01 level only when trials were synchronized to the Sender image appearance times. Overall, this effect was significant at the p = 4 × 10-8 Df = 175. To the best of our knowledge, this is the first study reporting statistically significant FC changes indicative of anomalous interactions between two sensorily isolated individuals.

Brain Functional Connectivity Changes in Rapid Eye Movement Sleep Behavior Disorder

The idiopathic rapid eye movement sleep behavior disorder (iRBD) has been reported as prodromal biomarker for neurodegenerative synucleinopathies. To early detect neurodegeneration in preclinical stage, pathophysiological changes of iRBD have been studied in many ways including structural magnetic resonance imaging (MRI), functional MRI (fMRI), and connectivity analyses. This review summarizes functional connectivity studies using resting-state fMRI in iRBD patients focused on motor-related network, compensatory mechanism of synucleinopathies, cognitive dysfunction, and non-motor symptoms.

Resting-state Functional Connectivity of the Motor and Cognitive Areas is Preserved in Masters Athletes

Aging is characterized by a decline in physical and cognitive functions, often resulting in decreased quality of life. Physical activity has been suggested to potentially slow down various aspects of the aging process, a theory that has been supported by studies of Masters Athletes (MA). For example, MA usually have better cognitive and physical functions than age-matched sedentary and healthy older adults (OA), making them a valuable model to gain insights into mechanisms that promote physical and cognitive function with aging. The purpose of this study was to identify differences in resting-state functional connectivity (rs-FC) of motor and cognitive regions between MA and OA and determine if these differences in the resting brain are associated with differences in cognitive and physical performance between groups. Fifteen MA (9 males) and 12 age-matched OA (six males) were included. rs-FC images were compared to identify significant between-groups differences in brain connectivity. There was higher connectivity between the cognitive and motor networks for the OA group, whereas the MA group had stronger connectivity between different regions within the same network, both for the cognitive and the motor networks. These results are in line with the literature suggesting that aging reduces the segregation between functional networks and causes regions within the same network to be less strongly connected. High-level physical activity practiced by the MA most likely contributes to attenuating aging-related changes in brain functional connectivity, preserving clearer boundaries between different functional networks, which may ultimately favor maintenance of efficient cognitive and sensorimotor processing.

Age-related changes in human brain functional connectivity using graph theory and machine learning techniques in resting-state fMRI data.

Aging is the basis of neurodegeneration and dementia that affects each endemic in the body.Normal aging in the brain is associated with progressive slowdown and disruptions in various abilities such as motor ability, cognitive impairment, decreasing information processing speed, attention, and memory. With the aggravation of global aging, more research focuses on brain changes in the elderly adult. The graph theory, in combination with functional magnetic resonance imaging (fMRI), makes it possible to evaluate the brain network functional connectivity patterns in different conditions with brain modeling. We have evaluated the brain network communication model changes in three different age groups (including 8 to 15years, 25 to 35years, and 45 to 75years) in lifespan pilot data from the human connectome project (HCP). Initially, Pearson correlation-based connectivity networks were calculated and thresholded. Then, network characteristics were compared between the three age groups by calculating the global and local graph measures. In the resting state brain network, we observed decreasing global efficiency and increasing transitivity with age. Also, brain regions, including the amygdala, putamen, hippocampus, precuneus, inferior temporal gyrus, anterior cingulate gyrus, and middle temporal gyrus, were selected as the most affected brain areas with age through statistical tests and machine learning methods. Using feature selection methods, including Fisher score and Kruskal-Wallis, we were able to classify three age groups using SVM, KNN, and decision-tree classifier. The best classification accuracy is in the combination of Fisher score and decision tree classifier obtained, which was 82.2%. Thus, by examining the measures of functional connectivity using graph theory, we will be able to explore normal age-related changes in the human brain, which can be used as a tool to monitor health with age.

Molecular basis underlying changes of brain entropy and functional connectivity in major depressive disorders after electroconvulsive therapy.

Electroconvulsive therapy (ECT) is widely used for treatment-resistant depression. However, it is unclear whether/how ECT can be targeted to affect brain regions and circuits in the brain to dynamically regulate mood and cognition. This study used brain entropy (BEN) to measure the irregular levels of brain systems in 46 major depressive disorder (MDD) patients before and after ECT treatment. Functional connectivity (FC) was further adopted to reveal changes of functional couplings. Moreover, transcriptomic and neurotransmitter receptor data were used to reveal genetic and molecular basis of the changes of BEN and functional connectivities. Compared to pretreatment, the BEN in the posterior cerebellar lobe (PCL) significantly decreased and FC between the PCL and the right temporal pole (TP) significantly increased in MDD patients after treatment. Moreover, we found that these changes of BEN and FC were closely associated with genes' expression profiles involved in MAPK signaling pathway, GABAergic synapse, and dopaminergic synapse and were significantly correlated with the receptor/transporter density of 5-HT, norepinephrine, glutamate, etc. CONCLUSION: These findings suggest that loops in the cerebellum and TP are crucial for ECT regulation of mood and cognition, which provides new evidence for the antidepressant effects of ECT and the potential molecular mechanism leading to cognitive impairment.

Effect of the closed-loop hippocampal low-frequency stimulation on seizure severity, learning, and memory in pilocarpine epilepsy rat model.

In this study, the anticonvulsant action of closed-loop, low-frequency deep brain stimulation (DBS) was investigated. In addition, the changes in brain rhythms and functional connectivity of the hippocampus and prefrontal cortex were evaluated. Epilepsy was induced by pilocarpine in male Wistar rats. After the chronic phase, a tripolar electrode was implanted in the right ventral hippocampus and a monopolar electrode in medial prefrontal cortex (mPFC). Subjects' spontaneous seizure behaviors were observed in continuous video recording, while the local field potentials (LFPs) were recorded simultaneously. In addition, spatial memory was evaluated by the Barnes maze test. Applying hippocampal DBS, immediately after seizure detection in epileptic animals, reduced their seizure severity and duration, and improved their performance in Barnes maze test. DBS reduced the increment in power of delta, theta, and gamma waves in pre-ictal, ictal, and post-ictal periods. Meanwhile, DBS increased the post-ictal-to-pre-ictal ratio of theta band. DBS decreased delta and increased theta coherences, and also increased the post-ictal-to-pre-ictal ratio of coherence. In addition, DBS increased the hippocampal-mPFC coupling in pre-ictal period and decreased the coupling in the ictal and post-ictal periods. Applying closed-loop, low-frequency DBS at seizure onset reduced seizure severity and improved memory. In addition, the changes in power, coherence, and coupling of the LFP oscillations in the hippocampus and mPFC demonstrate low-frequency DBS efficacy as an antiepileptic treatment, returning LFPs to a seemingly non-seizure state in subjects that received DBS.

Human brain activity and functional connectivity associated with verbal long-term memory consolidation across 1 month.

Declarative memories are initially dependent on the hippocampus and become stabilized through the neural reorganization of connections between the medial temporal lobe and neocortex. The exact time-course of these neural changes is not well established, although time-dependent changes in retrieval-related brain function can be detected across relatively short time periods in humans (e.g., hours to months). In a study involving older adults with normal cognition (N = 24), we investigated changes in brain activity and functional connectivity associated with the long-term memory consolidation of verbal material over one month. Participants studied fact-like, three-word sentences at 1-month, 1-week, 1-day, and 1-hour intervals before a recognition memory test inside an MRI scanner. Old/new recognition with confidence ratings and response times were recorded. We examined whole-brain changes in retrieval-related brain activity, as well as functional connectivity of the hippocampus and ventromedial prefrontal cortex (vmPFC), as memories aged from 1 hour to 1 month. Secondary analyses minimized the effect of confounding factors affected by memory age (i.e., changes in confidence and response time or re-encoding of targets). Memory accuracy, confidence ratings, and response times changed with memory age. A memory age network was identified where retrieval-related brain activity in cortical regions increased or decreased as a function of memory age. Hippocampal brain activity in an anatomical region of interest decreased with memory age. Importantly, these changes in retrieval-related activity were not confounded with changes in activity related to concomitant changes in behavior or encoding. Exploratory analyses of vmPFC functional connectivity as a function of memory age revealed increased connectivity with the posterior parietal cortex, as well as with the vmPFC itself. In contrast, hippocampal functional connectivity with the vmPFC and orbitofrontal cortex decreased with memory age. The observed changes in retrieval-related brain activity and functional connectivity align with the predictions of standard systems consolidation theory. These results suggest that processes consistent with long-term memory consolidation can be identified over short time periods using fMRI, particularly for verbal material.

How does the electric field induced by tDCS influence motor-related connectivity? Model-guided perspectives

Over the last decade, transcranial direct current stimulation (tDCS) has been applied not only to modulate local cortical activation, but also to address communication between functionally-related brain areas. Stimulation protocols based on simple two-electrode placements are being replaced by multi-electrode montages to target intra- and inter-hemispheric neural networks using multichannel/high definition paradigms. Objective. This study aims to investigate the characteristics of electric field (EF) patterns originated by tDCS experiments addressing changes in functional brain connectivity. Methods. A previous selection of tDCS experimental studies aiming to modulate motor-related connectivity in health and disease was conducted. Simulations of the EF induced in the cortex were then performed for each protocol selected. The EF magnitude and orientation are determined and analysed in motor-related cortical regions for five different head models to account for inter-subject variability. Functional connectivity outcomes obtained are qualitatively analysed at the light of the simulated EF and protocol characteristics, such as electrode position, number and stimulation dosing. Main findings. The EF magnitude and orientation predicted by computational models can be related with the ability of tDCS to modulate brain functional connectivity. Regional differences in EF distributions across subjects can inform electrode placements more susceptible to inter-subject variability in terms of brain connectivity-related outcomes. Significance. Neuronal facilitation/inhibition induced by tDCS fields may indirectly influence intra and inter-hemispheric connectivity by modulating neural components of motor-related networks. Optimization of tDCS using computational models is essential for adequate dosing delivery in specific networks related to clinically relevant connectivity outcomes.

Graph neural network and machine learning analysis of functional neuroimaging for understanding schizophrenia.

Graph representational learning can detect topological patterns by leveraging both the network structure as well as nodal features. The basis of our exploration involves the application of graph neural network architectures and machine learning to resting-state functional Magnetic Resonance Imaging (rs-fMRI) data for the purpose of detecting schizophrenia. Our study uses single-site data to avoid the shortcomings in generalizability of neuroimaging data obtained from multiple sites. The performance of our graph neural network models is on par with that of our machine learning models, each of which is trained using 69 graph-theoretical measures computed from functional correlations between various regions of interest (ROI) in a brain graph. Our deep graph convolutional neural network (DGCNN) demonstrates a promising average accuracy score of 0.82 and a sensitivity score of 0.84. This study provides insights into the role of advanced graph theoretical methods and machine learning on fMRI data to detect schizophrenia by harnessing changes in brain functional connectivity. The results of this study demonstrate the capabilities of using both traditional ML techniques as well as graph neural network-based methods to detect schizophrenia using features extracted from fMRI data. The study also proposes two methods to obtain potential biomarkers for the disease, many of which are corroborated by research in this area and can further help in the understanding of schizophrenia as a mental disorder.

The functional role of the pulvinar in discriminating between objective and subjective cognitive impairment in major depressive disorder.

Emotionally driven cognitive complaints represent a major diagnostic challenge for clinicians and indicate the importance of objective confirmation of the accuracy of depressive patients' descriptions of their cognitive symptoms. We compared cognitive status and structural and functional brain connectivity changes in the pulvinar and hippocampus between patients with total depression and healthy controls. The depressive group was also classified as "amnestic" or "nonamnestic," based on the members' subjective reports concerning their forgetfulness. We then sought to determine whether these patients would differ in terms of objective neuroimaging and cognitive findings. The right pulvinar exhibited altered connectivity in individuals with depression with objective cognitive impairment, a finding which was not apparent in depressive patients with subjective cognitive impairment. The pulvinar may play a role in depression-related cognitive impairments. Connectivity network changes may differ between objective and subjective cognitive impairment in depression and may play a role in the increased risk of dementia in patients with depression.

Neuropsychological, plasma marker, and functional connectivity changes in Alzheimer's disease patients infected with COVID-19.

Patients with COVID-19 may experience various neurological conditions, including cognitive impairment, encephalitis, and stroke. This is particularly significant in individuals who already have Alzheimer's disease (AD), as the cognitive impairments can be more pronounced in these cases. However, the extent and underlying mechanisms of cognitive impairments in COVID-19-infected AD patients have yet to be fully investigated through clinical and neurophysiological approaches. This study included a total of 77 AD patients. Cognitive functions were assessed using neuropsychiatric scales for all participants, and plasma biomarkers of amyloid protein and tau protein were measured in a subset of 25 participants. To investigate the changes in functional brain connectivity induced by COVID-19 infection, a cross-sectional neuroimaging design was conducted involving a subset of 37 AD patients, including a control group of 18 AD participants without COVID-19 infection and a COVID-19 group consisting of 19 AD participants. For the 77 AD patients between the stages of pre and post COVID-19 infection, there were significant differences in cognitive function and psychobehavioral symptoms on the Montreal Scale (MoCA), the neuropsychiatric inventory (NPI), the clinician's global impression of change (CIBIC-Plus), and the activity of daily living scale (ADL). The COVID-19 infection significantly decreased the plasma biomarker level of Aβ42 and increased the plasma p-tau181 level in AD patients. The COVID-19-infected AD patients show decreased local coherence (LCOR) in the anterior middle temporal gyrus and decreased global correlation (GCOR) in the precuneus and the medial prefrontal cortex. The findings suggest clinical, cognitive, and neural alterations following COVID-19 infection in AD patients and emphasize the need for close monitoring of symptoms in AD patients who have had COVID-19 and further exploration of the underlying mechanisms.

Altered brain connectivity, neuroinflammation and AD‐related markers following 7 days after repetitive mild traumatic brain injury in young wild‐type mice

AbstractBackgroundTraumatic brain injuries (TBI) substantially increase the risk for neurodegenerative disorders including tauopathies and synucleinopathies. Repetitive mild TBI (rmTBI) exacerbate damage in brain impacting cognitive and emotional processes through lifetime. Therefore, there is a critical need to identify the molecular mechanisms underlying TBI‐mediated brain dysfunction. In doing so, we can develop effective therapies as the etiology for dementia remain poorly understood. Our goal is to identify early, unbiased, and novel biomarkers of brain dysfunction following rmTBI. These include defects in the brain connectome and protein expression in the areas most functionally susceptible to damage following rmTBI.MethodTo do this, we exposed young male and female C57BL/6J wild‐type mice to two rmTBI (2 × 0.6 J impacts/24 h apart) using the closed head injury model of engineered rotational acceleration (CHIMERA) or sham procedures. We measured changes in brain functional connectivity (FC) using resting state functional MRI (rsfMRI) and graph theory, examined microstructural differences in white and grey matter regions through diffusion tensor imaging (DTI) analyses, surveyed neuropathological proteins using NanoString‐GeoMx Digital spatial protein profiling spatial profiling (DSP).ResultThe rsfMRI data revealed that rmTBI induces aberrant changes in the graph metrics such as node clustering coefficient, global and local efficiency, participation coefficient, eigenvector centrality, and betweenness centrality in brain regions processing visual, auditory, and somatosensory information. The optic tract and thalamus were the most affected regions showing significant differences in phospho‐tau (S199), neuroinflammatory markers (GFAP, Iba‐1, GPNMB), and other proteolytic (cathepsin‐D) and proliferation (ki‐67) cell markers. We identified extensive white matter damage, defects in brain FC, and exacerbated anatomically distinct protein profiles.ConclusionThese findings align with results reported in individuals with TBI such as diffuse axonal damage, glial activation, and functional network disruption in the visual tract and specific thalamic regions. Upcoming studies will evaluate the potential use of using brain imaging along with molecular markers to predict longitudinal damage after rmTBI.

Stress system dysfunction and changes in brain volume and functional connectivity in older adults with subclinical depressive symptoms

AbstractBackgroundSubclinical depressive symptoms are associated with increased risk of Alzheimer’s disease (AD). This link could be related to stress system dysfunction, known to occur in both depression and AD, and to depend notably on the hippocampus which is particularly sensitive to AD. We aimed at investigating the links between levels of blood stress markers and changes in brain regions involved in the stress response in older adults with subclinical depressive symptoms.MethodCognitively unimpaired older adults with (DepS; n = 73) or without (NoDepS; n = 58) subclinical depressive symptoms (defined using the 15‐item version of the Geriatric Depression Scale), from the baseline data of the Age‐Well trial (NCT02977819) were included. For each participant, levels of cortisol, epinephrine and norepinephrine were obtained from blood sampling. Moreover, the functional connectivity (FC) between, and the gray matter (GM) volume of, the hypothalamus, hippocampus and hippocampal subfields were extracted from resting‐state functional, and structural T1‐weighted, MRI. Levels of blood stress markers and neuroimaging measures were compared between groups. Regression analyses were then conducted between levels of blood markers and brain measures. Analyses were corrected for age, sex, education and anxiety symptoms with statistical significance set to p&lt;0.05.ResultHigher blood epinephrine level (p&lt;0.024), and FC between the hypothalamus and the CA1 hippocampal subfield (p&lt;0.040), was found in DepS compared to NoDepS (Fig.1). This higher epinephrine level was associated with greater FC between the hypothalamus and the CA1 (p&lt;0.007) and Subiculum (p&lt;0.013) subfields (Fig.2). Lower GM volume in the CA1 (p&lt;0.008) and DG/CA2‐3‐4 (p&lt;0.013) subfields was also found in the DepS group (Fig.3), but was not associated with epinephrine level. No significant between‐group difference in blood cortisol and norepinephrine levels was observed.ConclusionSubclinical depressive symptoms in aging are associated with higher blood epinephrine level related to greater FC between the hypothalamus and hippocampal subfields (CA1 and Subiculum) – suggesting an increased sympathetic nervous system activity. They are also associated with GM atrophy in specific hippocampal subfields, including the CA1 that is sensitive to AD. These two distinct mechanisms at this preclinical stage of depression may at least partly explain that depression is a risk factor for AD.

Association between gene expression and altered resting-state functional networks in type 2 diabetes

BackgroundType 2 diabetes (T2DM) is a polygenic metabolic disorder that accelerates brain aging and harms cognitive function. The underlying mechanism of T2DM-related brain functional changes has not been clarified.MethodsResting-fMRI data were obtained from 99 T2DM and 109 healthy controls (HCs). Resting-state functional connectivity networks (RSNs) were separated using the Independent Component Analysis (ICA) method, and functional connectivity (FC) differences between T2DM patients and HCs within the RSNs were detected. A partial least squares (PLS) regression was used to test the relation between gene expression from Allen Human Brain Atlas (AHBA) and intergroup FC differences within RSNs. Then the FC differences-related gene sets were enriched to determine the biological processes and pathways related to T2DM brain FC changes.ResultThe T2DM patients showed significantly increased FC in the left middle occipital gyrus (MOG) of the precuneus network (PCUN) and the right MOG / right precuneus of the dorsal attention network (DAN). FC differences within the PCUN were linked with the expression of genes enriched in the potassium channel and TrkB-Rac1 signaling pathways and biological processes related to synaptic function.ConclusionThis study linked FC and molecular alterations related to T2DM and suggested that the T2DM-related brain FC changes may have a genetic basis. This study hoped to provide a unique perspective to understand the biological substrates of T2DM-related brain changes.

Brain responses and connectivity to visual meal compositions: An EEG investigation into food liking

Understanding food liking, which shapes individual preferences for certain foods, is important for enhancing consumer satisfaction, encouraging healthier eating habits, and developing effective nutritional interventions. In this study, we aimed to investigate the neural underpinnings of food liking. We used electroencephalography (EEG) as a neuroscientific approach and visual food stimuli comprising various compositions of Korean meals. Our focus was to examine changes in brain responses and functional connectivity resulting from variations in visual meal compositions. The behavioral results showed that participants exhibited increased liking for meals with increased compositions. EEG source analysis demonstrated increased activity in the anterior insula, fusiform gyrus, precuneus, ventromedial prefrontal cortex, and medial orbitofrontal cortex (mOFC) and decreased activity in the dorsolateral prefrontal cortex (dlPFC) with increased meal liking. Furthermore, functional connectivity analysis revealed reduced connectivity between the dlPFC and both the mOFC and the anterior insula with increased meal liking. Notably, lower dlPFC-mOFC connectivity was associated with a greater preference for visual meal stimuli. Together, these results suggest that a decrease in neural communication between the brain regions responsible for subjective reward value processing and cognitive control, indicating a shift in attention towards the rewarding aspects of food, plays a significant role in food-liking decisions. Our study also emphasizes the integral role of various brain regions in determining food preference, thereby providing evidence for further neuroscientific investigations into dietary decision-making processes.