Functional Connectivity Of Brain Regions Research Articles

Enhancing local representation learning through global–local integration with functional connectivity for EEG-based emotion recognition

Emotion recognition based on electroencephalogram (EEG) signals is crucial in understanding human affective states. Current research has limitations in extracting local features. The representation capabilities of local features are limited, making it difficult to comprehensively capture emotional information. In this study, a novel approach is proposed to enhance local representation learning through global–local integration with functional connectivity for EEG-based emotion recognition. By leveraging the functional connectivity of brain regions, EEG signals are divided into global embeddings that represent comprehensive brain connectivity patterns throughout the entire process and local embeddings that reflect dynamic interactions within specific brain functional networks at particular moments. Firstly, a convolutional feature extraction branch based on the residual network is designed to extract local features from the global embedding. To further improve the representation ability and accuracy of local features, a multidimensional collaborative attention (MCA) module is introduced. Secondly, the local features and patch embedded local embeddings are integrated into the feature coupling module (FCM), which utilizes hierarchical connections and enhanced cross-attention to couple region-level features, thereby enhancing local representation learning. Experimental results on three public datasets show that compared with other methods, this method improves accuracy by 4.92% on the DEAP, by 1.11% on the SEED, and by 7.76% on the SEED-IV, demonstrating its superior performance in emotion recognition tasks.

Aberrant cerebral blood flow and functional connectivity in patients with vestibular migraine: a resting-state ASL and fMRI study

BackgroundPrior neuroimaging studies on vestibular migraine (VM) have extensively certified the functional and structural alterations in multiple brain regions and networks. However, few studies have assessed the cerebral blood flow (CBF) in VM patients using arterial spin labeling (ASL). The present study aimed to investigate CBF and functional connectivity (FC) alterations in VM patients during interictal periods.MethodsWe evaluated 52 VM patients and 46 healthy controls (HC) who received resting-state pseudo-continuous ASL and functional magnetic resonance imaging (fMRI) scanning. Comparisons of voxel-based CBF and seed-based FC were performed between the two groups. Brain regions showed significant group differences in CBF analyses were chosen as seeds in FC analyses. Additionally, the associations between abnormal imaging results and clinical features were explored.ResultsCompared with HC, VM patients showed higher normalized CBF in the right precentral gyrus (PreCG), left postcentral gyrus (PostCG), left superior frontal gyrus and bilateral insular (p < 0.05, FDR corrected). Furthermore, VM patients exhibited increased FC between the right PreCG and areas of the left PostCG, left cuneus and right lingual gyrus (p < 0.05, FDR corrected). In addition, we observed decreased FC between the left insular and regions of the left thalamus and right anterior cingulate cortex, as well as increased FC between the left insular and right fusiform gyrus in VM patients (p < 0.05, FDR corrected). Moreover, these variations in brain perfusion and FC were significantly correlated with multiple clinical features including frequency of migraine symptoms, frequency of vestibular symptoms and disease duration of VM (all p < 0.05).ConclusionsPatients with VM during interictal period showed hyperperfusion and abnormal resting-state FC in brain regions potentially contributed to disrupted multi-sensory and autonomic processing, as well as impaired ocular motor control, pain modulation and emotional regulation. Our study provided novel insights into the complex neuropathology of VM from a CBF perspective.

Effectiveness and mechanism of action of rTMS combined with quadriceps strength training in individuals with knee osteoarthritis: study protocol for a randomized controlled trial

BackgroundQuadriceps training is necessary in function and activity of daily living for patients with knee osteoarthritis (KOA). However, it did not reduce the rate of surgical treatment for end-stage KOA in the long term. This may be related to brain structure changes and maladaptive plasticity in KOA patients. Transcranial Magnetic Stimulation (TMS) could enhance the functional connectivity of brain regions and improves maladaptive plasticity. However, the synergistic effect of the combination of the two for treat KOA is still unclear. Therefore, the purpose of this study is to investigate whether the High-Frequency rTMS combined with quadriceps strength training can improve the pain and function in KOA more effectively than quadriceps training alone and explore the mechanism of action.MethodsThis study is an assessor-blind, sham-controlled, randomized controlled trial involving 12 weeks of intervention and 6 months follow-up. 148 participants with KOA will receive usual care management and be randomized into four subgroups equally, including quadriceps strength training, high-frequency rTMS training, sham rTMS and quadriceps strength training, high-frequency rTMS and quadriceps strength training. The rehabilitation interventions will be carried out 5 days per week for a total of 12 weeks. All outcomes will be measured at baseline, 4 weeks, 8 weeks, and 12 weeks during the intervention and 1 month, 3 months and 6 months during the follow-up period. The effectiveness outcomes will be included visual analog scale, isokinetic knee muscle strength, Knee Injury and Osteoarthritis Outcome score and 36-Item Short-Form Health Survey score; The act mechanism outcomes will be included motor evoked potential, grey matter density, white matter, subcortical nuclei volumes, cortical thickness and functional connectivity by MRI. Two-way of variance with repeated measures will be used to test the group and time effect for outcome measures.DiscussionThe study will be the first protocol to examine whether there are synergistic effects following high-frequency rTMS combined with quadriceps strength training for treat KOA and clarify the mechanism of action. High-frequency rTMS can be added into the training program for KOA patients if it is proven effective.Trial registrationChinese Clinical Trial Registry ChiCTR2300067617. Registered on Jan.13,2023.

Resting state functional connectivity associated with impaired proprioception post-stroke.

Deficits in proprioception, the knowledge of limb position and movement in the absence of vision, occur in ~50% of all strokes; however, our lack of knowledge of the neurological mechanisms of these deficits diminishes the effectiveness of rehabilitation and prolongs recovery. We performed resting-state functional magnetic resonance imaging (fMRI) on stroke patients to determine functional brain networks that exhibited changes in connectivity in association with proprioception deficits determined by a Kinarm robotic exoskeleton assessment. Thirty stroke participants were assessed for proprioceptive impairments using a Kinarm robot and underwent resting-state fMRI at 1 month post-stroke. Age-matched healthy control (n = 30) fMRI data were also examined and compared to stroke data in terms of the functional connectivity of brain regions associated with proprioception. Stroke patients exhibited reduced connectivity of the supplementary motor area and the supramarginal gyrus, relative to controls. Functional connectivity of these regions plus primary somatosensory cortex and parietal opercular area was significantly associated with proprioceptive function. The parietal lobe of the lesioned hemisphere is a significant node for proprioception after stroke. Assessment of functional connectivity of this region after stroke may assist with prognostication of recovery. This study also provides potential targets for therapeutic neurostimulation to aid in stroke recovery.

Differences in the distribution of triggers among resting state networks in patients with juvenile myoclonic epilepsy explained by network analysis.

Juvenile myoclonus epilepsy (JME) is an idiopathic generalized epilepsy syndrome. Functional connectivity studies based on graph theory have demonstrated changes in functional connectivity among different brain regions in patients with JME and healthy controls. However, previous studies have not been able to clarify why visual stimulation or increased cognitive load induces epilepsy symptoms in only some patients with JME. This study constructed a small-world network for the visualization of functional connectivity of brain regions in patients with JME, based on system mapping. We used the node reduction method repeatedly to identify the core nodes of the resting brain network of patients with JME. Thereafter, a functional connectivity network of the core brain regions in patients with JME was established, and it was analyzed manually with white matter tracks restriction to explain the differences in symptom distribution in patients with JME. Patients with JME had 21 different functional connections in their resting state, and no significant differences in their distribution were noted. The thalamus, cerebellum, basal ganglia, supplementary motor area, visual cortex, and prefrontal lobe were the core brain regions that comprised the functional connectivity network in patients with JME during their resting state. The betweenness centrality of the prefrontal lobe and the visual cortex in the core functional connectivity network of patients with JME was lower than that of the other brain regions. The functional connectivity and node importance of brain regions of patients with JME changed dynamically in the resting state. Abnormal discharges originating from the thalamus, cerebellum, basal ganglia, supplementary motor area, visual cortex, and prefrontal cortex are most likely to lead to seizures in patients with JME. Further, the low average value of betweenness centrality of the prefrontal and visual cortices explains why visual stimulation or increased cognitive load can induce epileptic symptoms in only some patients with JME.

Intrinsic Dynamics of Brain Functional Connectivity in Relation to Women’s Menstrual Cyclic Phases and its Impact on Their Stress, Life Satisfaction, and Social Distress

Research has reported that the fluctuations of sex hormones like estrogen and progesterone lead to neurological changes in the different brain regions across the menstrual cycle and its phases: menses, follicular, and luteal. Although some psychological changes have also been reported for women across their menstrual cycle, not enough studies have approached this topic from a neuropsychological perspective. For this reason, I am investigating brain connectivity fluctuations across a 32-day menstruation cycle and its impact on women’s life satisfaction (LS), perceived stress (PS), and emotional support (ES). For this study, I am using the data (n=406) that has been collected by the Human Connectome Project. I am using an experimental research methodology looking at correlations (connectivity) between brain regions and associated variables of menstrual cycle phases (menses, follicular, and luteal) across a 32-day menstrual cycle, and what this tells us about the participants’ LS, PS, and ES total scores. In neuroscience, artificial intelligence (AI) techniques are applied to understand complex brain functions, brain and behaviour relationships, and shows potential to diagnose neurological disorders and interventions. AI, and elastic net regression, which is a type of statistical technique for neuroimaging data, will be used to analyse the brain activity relationships that I am investigating. In my presentation, I aim to discuss whether functional connectivity in brain regions is linked to women’s LS, PS, and ES, and the implications of this for menstrual health. This pilot study, by using a big data set of relatively healthy participants to further our understanding of this topic, will help to open doors for future research with similar investigating aims for more impactful menstrual related health conditions like Premenstrual Syndrome and Premenstrual Dysphoric Disorder.

Longitudinal Functional Connectome in Pediatric Concussion: An Advancing Concussion Assessment in Pediatrics Study.

Advanced magnetic resonance imaging (MRI) techniques indicate that concussion (i.e., mild traumatic brain injury) disrupts brain structure and function in children. However, the functional connectivity of brain regions within global and local networks (i.e., functional connectome) is poorly understood in pediatric concussion. This prospective, longitudinal study addressed this gap using data from the largest neuroimaging study of pediatric concussion to date to study the functional connectome longitudinally after concussion as compared with mild orthopedic injury (OI). Children and adolescents (n = 967) 8-16.99 years with concussion or mild OI were recruited from pediatric emergency departments within 48 h post-injury. Pre-injury and 1-month post-injury symptom ratings were used to classify concussion with or without persistent symptoms based on reliable change. Subjects completed a post-acute (2-33 days) and chronic (3 or 6 months via random assignment) MRI scan. Graph theory metrics were derived from 918 resting-state functional MRI scans in 585 children (386 concussion/199 OI). Linear mixed-effects modeling was performed to assess group differences over time, correcting for multiple comparisons. Relative to OI, the global clustering coefficient was reduced at 3 months post-injury in older children with concussion and in females with concussion and persistent symptoms. Time post-injury and sex moderated group differences in local (regional) network metrics of several brain regions, including degree centrality, efficiency, and clustering coefficient of the angular gyrus, calcarine fissure, cuneus, and inferior occipital, lingual, middle occipital, post-central, and superior occipital gyrus. Relative to OI, degree centrality and nodal efficiency were reduced post-acutely, and nodal efficiency and clustering coefficient were reduced chronically after concussion (i.e., at 3 and 6 months post-injury in females; at 6 months post-injury in males). Functional network alterations were more robust and widespread chronically as opposed to post-acutely after concussion, and varied by sex, age, and symptom recovery at 1-month post-injury. Local network segregation reductions emerged globally (across the whole brain network) in older children and in females with poor recovery chronically after concussion. Reduced functioning between neighboring regions could negatively disrupt specialized information processing. Local network metric alterations were demonstrated in several posterior regions that are involved in vision and attention after concussion relative to OI. This indicates that functioning of superior parietal and occipital regions could be particularly susceptibile to the effects of concussion. Moreover, those regional alterations were especially apparent at later time periods post-injury, emerging after post-concussive symptoms resolved in most and persisted up to 6 months post-injury, and differed by biological sex. This indicates that neurobiological changes continue to occur up to 6 months after pediatric concussion, although changes emerge earlier in females than in males. Changes could reflect neural compensation mechanisms.

Daily Cannabidiol Administration for 10 Weeks Modulates Hippocampal and Amygdalar Resting-State Functional Connectivity in Cannabis Users: A Functional Magnetic Resonance Imaging Open-Label Clinical Trial.

Introduction: Cannabis use is associated with brain functional changes in regions implicated in prominent neuroscientific theories of addiction. Emerging evidence suggests that cannabidiol (CBD) is neuroprotective and may reverse structural brain changes associated with prolonged heavy cannabis use. In this study, we examine how an ∼10-week exposure of CBD in cannabis users affected resting-state functional connectivity in brain regions functionally altered by cannabis use. Materials and Methods: Eighteen people who use cannabis took part in a ∼10 weeks open-label pragmatic trial of self-administered daily 200 mg CBD in capsules. They were not required to change their cannabis exposure patterns. Participants were assessed at baseline and post-CBD exposure with structural magnetic resonance imaging (MRI) and a functional MRI resting-state task (eyes closed). Seed-based connectivity analyses were run to examine changes in the functional connectivity of a priori regions-the hippocampus and the amygdala. We explored if connectivity changes were associated with cannabinoid exposure (i.e., cumulative cannabis dosage over trial, and plasma CBD concentrations and Δ9-tetrahydrocannabinol (THC) plasma metabolites postexposure), and mental health (i.e., severity of anxiety, depression, and positive psychotic symptom scores), accounting for cigarette exposure in the past month, alcohol standard drinks in the past month and cumulative CBD dose during the trial. Results: Functional connectivity significantly decreased pre-to-post the CBD trial between the anterior hippocampus and precentral gyrus, with a strong effect size (d=1.73). Functional connectivity increased between the amygdala and the lingual gyrus pre-to-post the CBD trial, with a strong effect size (d=1.19). There were no correlations with cannabinoids or mental health symptom scores. Discussion: Prolonged CBD exposure may restore/reduce functional connectivity differences reported in cannabis users. These new findings warrant replication in a larger sample, using robust methodologies-double-blind and placebo-controlled-and in the most vulnerable people who use cannabis, including those with more severe forms of Cannabis Use Disorder and experiencing worse mental health outcomes (e.g., psychosis, depression).

Resting-state functional magnetic resonance imaging in bipolar affective disorder. A systematized umbrella review

Bipolar affective disorder (BD) is a complex mental illness that presents diagnostic challenges due to its heterogeneous nature. As a result, identifying potential markers for the disorder is crucial for effective diagnosis and treatment. Resting-state functional magnetic resonance imaging (rs-fMRI) is a promising non-invasive technique that provides a window into the pathophysiological characteristics of psychiatric and neurological diseases in vivo. The amount of data accumulated in the scientific community regarding changes in spontaneous activity and functional connectivity of brain regions in BD necessitates a comprehensive synthesis to determine the spectrum of disorders. Accordingly, a systematic review of reviews was conducted to summarize the changes characteristic of patients with BD as measured by fMRI. Qualitative synthesis of results of nine systematic reviews and six meta-analyses has allowed the definition of changes in spontaneous activity and functional connectivity most characteristic for BD, confirming the unity of functional disturbances of this nosological unit. The findings of the review indicate that the manic state in BD is often associated with increased activity of the amygdala and decreased functional connectivity between the amygdala and frontal regions. Conversely, the depressive phase is characterized by abnormalities of functional connectivity within the default mode network, particularly in relation to the posterior cingulate cortex. Changes in functional connectivity during periods of euthymia may reflect residual manifestations of one of the exacerbation phases or may be associated with a history of a psychotic episode. Furthermore, a comparative analysis of possible methods of quantitative fMRI data synthesis has been conducted for the first time in Russia, which is a valuable contribution to the field.

Dissociation of energy connectivity and functional connectivity in Alzheimer's disease is associated with maintenance of cognitive performance

The correlation between functional connectivity (FC) network segregation, glucose metabolism and cognitive decline has been recently identified. The coupling relationship between glucose metabolism and the intensity of neuronal activity obtained using hybrid PET/MRI techniques can provide additional information on the physiological state of the brain in patients with AD and mild cognitive impairment (MCI). It is a valuable task to use the above rules for constructing biomarkers that are closely related to the cognitive ability of individuals to monitor the pathological status of patients. This study proposed the concept of the energy connectivity (EC) network and its construction method. We hypothesized that the dissociation between energy connectivity and functional connectivity of brain regions is a valid indicator of cognitive ability in patients with dementia. The number of EC-attenuated brain regions (EC-AR) and the number of FC-attenuated brain regions (FC-AR) are obtained by comparison with the normal group, and the dissociation between functional connectivity and energy connectivity is indicated using the ratio of FC-AR to EC-AR for individuals in the disease group. The findings suggest that FC-AR/EC-AR values are accurate predictors of cognitive performance, while taking into account the cognitive recovery due to compensatory effects of the brain. The cognitive ability of some patients with cognitive recovery can also be predicted more accurately. This also indicates that lower functional connectivity and higher energy connectivity between network modules may be one of the important features that maintain cognitive performance. The concept of energy connectivity also has potential to help explore the pathological state of AD.

Functional hyperconnectivity is associated with higher levels of sPDGFRβ, a marker of blood brain barrier breakdown, in older adults

AbstractBackgroundApolipoprotein E4 (APOE4) has toxic effects on the cerebrovascular system, neuronal function, and functional connectivity of brain networks (e.g., default‐mode, frontal‐attention, and salience networks). The thalamus, a vital structure that acts as a relay station between many networks, has become of interest in AD research with studies showing atrophy among those with early AD and diminished cortical‐thalamic connections among those with vascular impairment. Additionally, CSF soluble platelet‐derived growth factor receptor‐β (sPDGFRβ), a marker of blood‐brain barrier breakdown, has been associated with AD risk, especially in APOE4 carriers. The present study investigated the relationship between CSF sPDGFRβ and functional connectivity in APOE4 carriers and non‐carriers.MethodOne hundred sixty‐six older adults from the Los Angeles area were selected from a larger cohort (96 females, mean age±SD = 67.4±10.7, 68 APOE4 carriers) based on availability of rsfMRI data. Image data was processed using CONN‐toolbox v19c. Grey matter was parcellated using Harvard/Oxford brain atlas, excluding cerebellum. ROI‐to‐ROI analyses were conducted selecting the thalamus as seed region averaging mean connectivity between the left and right structure of other parcellated brain regions. Linear regression models evaluated significant associations between blood oxygen level‐dependent (BOLD) and network connectivity among seed‐target regions and CSF sPDGFRβvalues, while covarying for age and sex. Comparison of averaged functional connectivity values between seed and all target regions among APOE4 carriers and non‐carriers was also examined.ResultHigher functional connectivity between the thalamus and resting state network hub regions were associated with higher CSF sPDGFRβ (Fig 1A, 1C). Cortical regions within the networks included posterior cingulate gyrus, anterior cingulate gyrus, and frontal eye field. Averaged functional connectivity between these areas was significantly higher in APOE4 carriers compared to non‐carriers (Fig 1B).ConclusionThe thalamus is a key subcortical structure for relaying signals across the brain for memory, attention and sleep/wakefulness cycles, and more recently with relevance to AD. These findings suggest a link between early BBB breakdown and elevated functional connectivity in brain regions known to have high synaptic activity and early pathology among non‐demented older adults at risk for AD.

The impact of wearing a KN95 face mask on human brain function: evidence from resting state functional magnetic resonance imaging.

Face masks are widely used in daily life because of the COVID-19 pandemic. The objective of this study was to explore the impact of wearing face masks on brain functions by using resting-state functional MRI (RS-fMRI). Scanning data from 15 healthy subjects (46.20 ± 6.67 years) were collected in this study. Each subject underwent RS-fMRI scans under two comparative conditions, wearing a KN95 mask and natural breathing (no mask). The amplitude of low frequency fluctuation (ALFF) and functional connectivity under the two conditions were analyzed and then compared using the paired t-test. Compared with those of the no-mask condition, the ALFF activities when wearing masks were increased significantly in the right middle frontal gyrus, bilateral precuneus, right superior marginal gyrus, left inferior parietal gyrus, and left supplementary motor area and decreased significantly in the anterior cingulate gyrus, right fusiform gyrus, left superior temporal gyrus, bilateral lingual gyrus, and bilateral calcarine cortex (p < 0.05). Taking the posterior cingulate cortex area as a seed point, the correlations with the occipital cortex, prefrontal lobe, and motor sensory cortex were sensitive to wearing masks compared with not wearing masks (p < 0.05). Taking the medial prefrontal cortex region as a seed point, the functional connectivity with the bilateral temporal lobe, bilateral motor sensory cortex, and occipital lobe was influenced by wearing a KN95 mask (p < 0.05). This study demonstrated that wearing a KN95 face mask can cause short-term changes in human resting brain function. Both local neural activities and functional connectivity in brain regions were sensitive to mask wearing. However, the neural mechanism causing these changes and its impact on cognitive function still need further investigation.

Impact of childhood trauma on the abnormal functional connectivity of brain regions in the fear network model of panic disorder

BackgroundPeople who have suffered childhood trauma may be more susceptible to panic disorder (PD). Existing evidence indicates that childhood trauma can significantly impact brain function. Meanwhile, the brain regions involved in the fear network model (FNM) of PD highly overlap with the brain regions affected by childhood trauma. However, it remains unclear whether functional connections between brain regions associated with the FNM in patients with PD are affected by childhood trauma. This study aimed to investigate the effects of childhood trauma on the functional connectivity (FC) of brain regions associated with the FNM in patients with PD. MethodThis study recruited 62 patients with PD, including 21 with a high level of childhood trauma (PD_HCT), 41 with a low level of childhood trauma (PD_LCT), and 40 healthy controls (HCs). The patients underwent magnetic resonance imaging resting-state scanning. The amygdala, anterior cingulate, thalamus, and hippocampus were chosen as regions of interest (ROIs) to examine group differences in ROIs and whole-brain resting-state FC (rsFC). ResultsCompared with PD_HCT patients, PD_LCT patients exhibited significantly increased rsFC in the right thalamus, right temporo-occipital middle temporal gyrus, left thalamus, and right temporo-occipital middle temporal gyrus. Compared with HCs, PD_LCT patients had increased rsFC between the right thalamus and the right temporo-occipital middle temporal gyrus. ConclusionPatients with PD who had suffered high and low levels of childhood trauma were found to exhibit different pathological rsFC alterations in the FNM, suggesting that childhood trauma may be an important risk factor for the development of PD symptoms.

Lifestyle risks associated with brain functional connectivity and structure.

Some lifestyle factors are related to health and brain function and structure, but the brain systems involved are incompletely understood. A general linear model was used to test the associations of the combined and separate lifestyle risk measures of alcohol use, smoking, diet, amounts of physical activity, leisure activity, and mobile phone use, with brain functional connectivity with the high resolution Human Connectome Project (HCP) atlas in 19,415 participants aged 45-78 from the UK Biobank, with replication with HCP data. Higher combined lifestyle risk scores were associated with lower functional connectivity across the whole brain, but especially of three brain systems. Low physical, and leisure and social, activity were associated with low connectivities of the somatosensory/motor cortical regions and of hippocampal memory-related regions. Low mobile phone use, perhaps indicative of poor social communication channels, was associated with low functional connectivity of brain regions in and related to the superior temporal sulcus that are involved in social behavior and face processing. Smoking was associated with lower functional connectivity of especially frontal regions involved in attention. Lower cortical thickness in some of these regions, and also lower subcortical volume of the hippocampus, amygdala, and globus pallidus, were also associated with the sum of the poor lifestyle scores. This very large scale analysis emphasizes how the lifestyle of humans relates to their brain structure and function, and provides a foundation for understanding the causalities that relate to the differences found here in the brains of different individuals.

Geography education improves spatial ability: evidence from fMRI and behavioral experiments

ABSTRACT Previous behavior experimental studies indicate that geography education facilitates the development of students’ spatial ability. However, it is unclear how geography education shapes student brain activity and promotes spatial ability. In this article, we proposed a neuroscience-based method to explore the relationship between geography education and spatial ability. We conducted a behavioral experiment with 63 participants and an fMRI experiment with 49 participants. All the participants were divided into groups according to their undergraduate years and majors completed four spatial ability tasks. The fMRI and behavioral results revealed that after four years of geography education, students had greater mental rotation, spatial visualization and spatial relation reasoning abilities than non-geography students. The activation and functional connectivity of brain regions further indicated that geography education improved students’ spatial reference, spatial memory, visual attention and spatial decision-making. Our findings offer new neuroscience evidence that geography education can improve the spatial ability of undergraduate students, and provide new neuroimaging approach for geographic talent cultivation and curriculum assessment.

Neutrophil-to-Lymphocyte Ratio Amplifies the Effects of Aging on Decrements in Grip Strength and Its Functional Neural Underpinnings.

The neutrophil-to-lymphocyte ratio (NLR) is a trans-prognostic biomarker of physiologic stress and inflammation linked to muscle weakness in older adults. Generation of grip force coincides with sustained activity in the primary sensorimotor cortex (SM1). The current study investigates whether whole-brain functional connectivity, that is, degree centrality (CD) of SM1 relates to grip strength and whether both functional measures are predicted by advancing age as a function of the NLR. Astructural regression model investigated the main and interactive effects of age and NLR on grip strength and CD of SM1 in 589 adults aged 21-85years (M=45.87, SD=18.06). The model including the entire sample had a good fit (χ 2(4)=1.63, p=.804). In individuals aged 50years and older, age predicted lower grip strength and SM1 CD as a function of increasing NLR. In a model stratified by sex, the effect of age, NLR, and their interaction on grip strength are significant for older men but not older women. Analyses support CD of SM1 at rest as a neural biomarker of grip strength. Grip and its neural underpinnings decrease with advancing age and increasing NLR in mid to late life. Age-related decrements in grip strength and functional connectivity of brain regions involved in the generation of dynamic grip appear to be accelerated as a function of systemic physiological stress and inflammation, particularly in older men.

The mechanism and effect of repetitive transcranial magnetic stimulation for post-stroke pain.

Post-stroke pain (PSP) is a common complication after stroke and affects patients' quality of life. Currently, drug therapy and non-invasive brain stimulation are common treatments for PSP. Given the poor efficacy of drug therapy and various side effects, non-invasive brain stimulation, such as repetitive transcranial magnetic stimulation (rTMS), has been accepted by many patients and attracted the attention of many researchers because of its non-invasive and painless nature. This article reviews the therapeutic effect of rTMS on PSP and discusses the possible mechanisms. In general, rTMS has a good therapeutic effect on PSP. Possible mechanisms of its analgesia include altering cortical excitability and synaptic plasticity, modulating the release of related neurotransmitters, and affecting the structural and functional connectivity of brain regions involved in pain processing and modulation. At present, studies on the mechanism of rTMS in the treatment of PSP are lacking, so we hope this review can provide a theoretical basis for future mechanism studies.

Altered regional homogeneity and its association with cognitive function in adolescents with borderline personality disorder.

Adolescents with borderline personality disorder often have cognitive impairment, but the underlying mechanism for this is not clear. This study was aimed at assessing alterations in regional homogeneity using resting-state functional MRI (fMRI) in adolescents with borderline personality disorder, and evaluating the associations between regional homogeneity and cognitive testing scores. We enrolled 50 adolescents with borderline personality disorder (age 12-17 years) and 21 age- and sex-matched healthy controls. We performed regional homogeneity and seed-based functional connectivity analysis for both groups. We also performed correlative analysis for regional homogeneity and cognitive testing scores. Compared with healthy controls, adolescents with borderline personality disorder had reduced regional homogeneity values in the frontal cortex (including the left inferior orbitofrontal cortex and the bilateral superior frontal cortex) as well as in the left precuneus in the default mode network. Adolescents with borderline personality disorder also had higher regional homogeneity values in several cortical regions: the right middle temporal gyrus, the right cuneus, the right precentral gyrus and the left middle occipital gyrus. Regional homogeneity values in the left middle occipital gyrus, left inferior orbitofrontal cortex and right superior frontal gyrus were associated with cognitive testing scores in adolescents with borderline personality disorder. We also found increased functional connectivity between the left middle occipital gyrus and right superior frontal gyrus in adolescents with borderline personality disorder. This study had a modest sample size, with a possible case selection bias for patients with more severe illness. This cohort also included patients with comorbidities or taking psychotropic medications, which may have confounded study results. Alterations in regional homogeneity and functional connectivity in brain regions that involve the limbic-cortical circuit could be neural correlates for cognitive impairment in adolescents with borderline personality disorder.

Alterations in Functional Connectivity of Thalamus and Primary Somatosensory Cortex in Painful and Painless Diabetic Peripheral Neuropathy.

In this study we aimed to investigate the functional connectivity of brain regions involved in sensory processing in diabetes with and without painful and painless diabetic peripheral neuropathy (DPN) and the association with peripheral nerve function and pain intensity. In this cross-sectional study we used resting-state functional MRI (fMRI) to investigate functional brain connectivity of 19 individuals with type 1 diabetes and painful DPN, 19 with type 1 diabetes and painless DPN, 18 with type 1 diabetes without DPN, and 20 healthy control subjects. Seed-based connectivity analyses were performed for thalamus, postcentral gyrus, and insula, and the connectivity z scores were correlated with peripheral nerve function measurements and pain scores. Overall, compared with those with painful DPN and healthy control subjects, subjects with type 1 diabetes without DPN showed hyperconnectivity between thalamus and motor areas and between postcentral gyrus and motor areas (all P ≤ 0.029). Poorer peripheral nerve functions and higher pain scores were associated with lower connectivity of the thalamus and postcentral gyrus (all P ≤ 0.043). No connectivity differences were found in insula (all P ≥ 0.071). Higher functional connectivity of thalamus and postcentral gyrus appeared only in diabetes without neuropathic complications. Thalamic/postcentral gyral connectivity measures demonstrated an association with peripheral nerve functions. Based on thalamic connectivity, it was possible to group the phenotypes of type 1 diabetes with painful/painless DPN and type 1 diabetes without DPN. The results of the current study support that fMRI can be used for phenotyping, and with validation, it may contribute to early detection and prevention of neuropathic complications.

The Effects of 3D Custom Foot Orthotics with Mechanical Plantar Stimulation in Older Individuals with Cognitive Impairment: A Pilot Study.

Recent scientific evidence supports the idea that foot plantar stimulation increases the functional connectivity of brain regions involved in visuo-spatial and sensory-motor integration. In this before-after, non-randomised intervention study we assessed the change in several gait and postural parameters using inertial sensor measurements after acute plantar stimulation using custom 3D-printed insoles. The pilot study was performed on 22 institutionalised, older individuals with a high comorbidity burden who either walked autonomously or with the help of a cane. The intensity of the effects in the first mechanical plantar stimulation session (at one week) strongly predicted a change in the 180° turn duration (p &lt; 0.05) and the standard deviation of the step duration (p &lt; 0.05) during the timed up-and-go test. Based on these effects, researchers also predicted decreases in some postural parameters such as the root mean square of displacement on the anterior-posterior axis (p &lt; 0.01). Thus, these preliminary findings provide a strong rationale for performing controlled clinical trials with larger samples to investigate the efficacy and mechanisms of mechanical plantar stimulation in frail elderly individuals.