•One of the first integrative methods in literature to jointly estimate a collection of unknown dynamic networks for a group of individuals, guided by covariate information, which involves ...significant methodological and computational novelty. We develop the approach for both dynamic pairwise correlations and partial correlations.•The proposed method is able to systematically borrow information across heterogeneous samples in an unsupervised manner in order to compute individual-specific dynamic networks. This results in considerable gains in estimation accuracy by leveraging common connectivity patterns•In addition to estimating individual level networks, the method is able to identify subgroups of individuals with similar dynamic connectivity patterns and report subgroup level network characteristics that are more robust to noise and heterogeneity in the samples.•Extensive numerical studies illustrate significant gains due to incorporation of covariate information, and also relative to existing single-subject and multi-subject dynamic connectivity approaches, in terms of recovering the true dynamic network structure.•Our analysis of fMRI block task data illustrated the considerable advantages of systematically borrowing information across samples under the proposed approach compared to existing dynamic connectivity methods. Alternate single-subject analyses fail to detect connectivity change points that is biologically impractical in a block task experiment.
Although there is a rapidly growing literature on dynamic connectivity methods, the primary focus has been on separate network estimation for each individual, which fails to leverage common patterns of information. We propose novel graph-theoretic approaches for estimating a population of dynamic networks that are able to borrow information across multiple heterogeneous samples in an unsupervised manner and guided by covariate information. Specifically, we develop a Bayesian product mixture model that imposes independent mixture priors at each time scan and uses covariates to model the mixture weights, which results in time-varying clusters of samples designed to pool information. The computation is carried out using an efficient Expectation-Maximization algorithm. Extensive simulation studies illustrate sharp gains in recovering the true dynamic network over existing dynamic connectivity methods. An analysis of fMRI block task data with behavioral interventions reveal sub-groups of individuals having similar dynamic connectivity, and identifies intervention-related dynamic network changes that are concentrated in biologically interpretable brain regions. In contrast, existing dynamic connectivity approaches are able to detect minimal or no changes in connectivity over time, which seems biologically unrealistic and highlights the challenges resulting from the inability to systematically borrow information across samples.
Changes in regional levels of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) may indicate the potential for favorable responses to the treatment of stroke affecting the upper ...extremity. By selectively altering GABA levels during training, we may induce long-term potentiation and adjust excitatory/inhibitory balance (E/I balance). However, the impact of this alteration may be limited by neural damage or aging. Aerobic exercise has been shown to increase GABA levels in the sensorimotor cortex and improve motor learning by widening the dynamic range of E/I balance. The cross-sectional project, Effects of Acute Exercise on Functional Magnetic Resonance Spectroscopy Measures of GABA in Aging and Chronic Stroke (EASE), is designed to assess the functional relevance of changes in GABA concentration within the sensorimotor cortex before and after an acute aerobic exercise session. EASE will enroll 30 participants comprised of healthy younger adults (18-35 years; n = 10), older adults (60+ years; n = 10), and persons with chronic stroke (n = 10) affecting distal upper extremity function. We will use resting magnetic resonance spectroscopy to measure all participants' GABA levels at rest before and after aerobic exercise. In addition, we will employ functional magnetic resonance spectroscopy using motor skill acquisition and recall tasks in healthy adults. We hypothesize that acute aerobic exercise will increase resting sensorimotor GABA concentration and that higher GABA resting levels will predict better motor learning performance on measures taken both inside and outside the magnet. We also hypothesize that a higher dynamic range of GABA during task-based spectroscopy in healthy adults will predict better motor skill acquisition and recall. The EASE project will evaluate the effect of acute exercise on GABA levels as a biomarker of upper extremity motor skill learning with two populations (aging adults and those with chronic stroke). We predict that acute exercise, higher sensorimotor GABA levels, and broader dynamic range will be related to better motor skill acquisition.
Despite over 140years of research on Broca's area, the connections of this region to medial frontal cortex remain unclear. The current study investigates this structural connectivity using ...diffusion-weighted MRI tractography in living humans. Our results show connections between Broca's area and Brodmann's areas (BA) 9, 8, and 6 (both supplementary motor area (SMA) in caudal BA 6, and Pre-SMA in rostral BA 6). Trajectories follow an anterior-to-posterior gradient, wherein the most anterior portions of Broca's area connect to BA 9 and 8 while posterior Broca's area connects to Pre-SMA and SMA. This anterior–posterior connectivity gradient is also present when connectivity-based parcellation of Broca's area is performed. Previous studies of language organization suggest involvement of anterior Broca's area in semantics and posterior Broca's area in syntax/phonology. Given corresponding patterns of functional and structural organization of Broca's area, it seems well warranted to investigate carefully how anterior vs. posterior medial frontal cortex differentially affect semantics, syntax and phonology.
Rehabilitation approaches for individuals with neurologic conditions have increasingly shifted toward promoting neuroplasticity for enhanced recovery and restoration of function. This review focuses ...on exercise strategies and non-invasive neuromodulation techniques that target neuroplasticity, including transcranial magnetic stimulation (TMS), vagus nerve stimulation (VNS), and peripheral nerve stimulation (PNS). We have chosen to focus on non-invasive neuromodulation techniques due to their greater potential for integration into routine clinical practice. We explore and discuss the application of these interventional strategies in four neurological conditions that are frequently encountered in rehabilitation settings: Parkinson's Disease (PD), Traumatic Brain Injury (TBI), stroke, and Spinal Cord Injury (SCI). Additionally, we discuss the potential benefits of combining non-invasive neuromodulation with rehabilitation, which has shown promise in accelerating recovery. Our review identifies studies that demonstrate enhanced recovery through combined exercise and non-invasive neuromodulation in the selected patient populations. We primarily focus on the motor aspects of rehabilitation, but also briefly address non-motor impacts of these conditions. Additionally, we identify the gaps in current literature and barriers to implementation of combined approaches into clinical practice. We highlight areas needing further research and suggest avenues for future investigation, aiming to enhance the personalization of the unique neuroplastic responses associated with each condition. This review serves as a resource for rehabilitation professionals and researchers seeking a comprehensive understanding of neuroplastic exercise interventions and non-invasive neuromodulation techniques tailored for specific diseases and diagnoses.
We have previously demonstrated that aerobic exercise improves upper extremity motor function concurrent with changes in motor cortical activity using task-based functional magnetic resonance imaging ...(fMRI). However, it is currently unknown how a 12-week aerobic exercise intervention affects resting-state functional connectivity (rsFC) in motor networks. Previous work has shown that over a 6-month or 1-year exercise intervention, older individuals show increased resting state connectivity of the default mode network and the sensorimotor network (Voss et al., 2010b; Flodin et al., 2017). However, the effects of shorter-term 12-week exercise interventions on functional connectivity have received less attention.
Thirty-seven sedentary right-handed older adults were randomized to either a 12-week aerobic, spin cycling exercise group or a 12-week balance-toning exercise group. Resting state functional magnetic resonance images were acquired in sessions PRE/POST interventions. We applied seed-based correlation analysis to left and right primary motor cortices (L-M1 and R-M1) and anterior default mode network (aDMN) to test changes in rsFC between groups after the intervention. In addition, we performed a regression analysis predicting connectivity changes PRE/POST intervention across all participants as a function of time spent in aerobic training zone regardless of group assignment.
Seeding from L-M1, we found that participants in the cycling group had a greater PRE/POST change in rsFC in aDMN as compared to the balance group. When accounting for time in aerobic HR zone, we found increased heart rate workload was positively associated with increased change of rsFC between motor networks and aDMN. Interestingly, L-M1 to aDMN connectivity changes were also related to motor behavior changes in both groups. Respective of M1 laterality, comparisons of all participants from PRE to POST showed a reduction in the extent of bilateral M1 connectivity after the interventions with increased connectivity in dominant M1.
A 12-week physical activity intervention can change rsFC between primary motor regions and default mode network areas, which may be associated with improved motor performance. The decrease in connectivity between L-M1 and R-M1 post-intervention may represent a functional consolidation to the dominant M1.
Neuroimaging, Aging.
Previous work has shown that older adults who evidence increased right inferior frontal gyrus (IFG) activity during language tasks show decreased sematic verbal fluency performance. The current study ...sought to evaluate if an aerobic exercise intervention can alter patterns of brain activity during a semantic verbal fluency task assessed by functional magnetic resonance imaging (fMRI). Thirty-two community-dwelling, sedentary older adults were enrolled to a 12-week aerobic “Spin” exercise group or a 12-week nonaerobic exercise control condition (Balance). Thirty participants completed their assigned intervention (16 Spin; 14 Balance) with pre- and postintervention assessments of a semantic verbal fluency task during fMRI and estimated VO2max testing. There was a significant increase in the change scores for estimated VO2max of the Spin group when compared to the Balance group. Semantic verbal fluency output within the scanner was also improved in the Spin group as compared to controls at postassessment. Group fMRI comparisons of IFG activity showed lower activity in the right IFG following the intervention in the aerobic Spin group when compared to the Balance group. Regression analysis of imaging data with change in both estimated VO2max and semantic verbal fluency was negatively correlated with activity in right IFG. The current work is registered as clinical trial with NCT01787292 and NCT02787655.
264 Building Empowerment through FITness (BeFIT) McCall, Kimberly; McGregor, Keith; Layne, Shellie ...
Journal of clinical and translational science,
04/2024, Letnik:
8, Številka:
s1
Journal Article
Recenzirano
Odprti dostop
OBJECTIVES/GOALS: Improving physical activity of African American women experiencing disproportionate health risks from sedentarism, educational and socio-environmental barriers. BeFit: Building ...Empowerment through Fitness is based on “What I Learned At Home” project, run by Women Under Construction Network, for residents of the Birmingham Housing Authority. METHODS/STUDY POPULATION: A qualitative study design to understand unique cultural context and challenges faced by African American women residing in the Birmingham Housing Authority, regarding physical activity engagement, including sedentarism. A needs assessment approach will help determine barriers, support systems, and social networks. Semi-structured, pre, mid, and post program focus groups will identify challenges and opportunities for health, such as diet and exercise, and will be analyzed by hand with a thematic analysis. The project framework uses exercise and home repair tools with a life-building/life repair curriculum to influence health, self-efficacy, and program engagement. The Study enrollment will include 50 women over two cohorts in a 12-week project. RESULTS/ANTICIPATED RESULTS: This research addresses the urgent health needs of African American women in low-income communities. These women face heightened health risks due to sedentary lifestyles, educational gaps, and socio-environmental barriers. This project targets the pronounced prevalence of allostatic burden in this population by applying a culturally sensitive, bottom-up approach. Our goal of incorporating healthy lifestyles to improve health in at-risk women and their families requires multiple projects. This project is a necessary first step in engaging with a community to identify local environmental circumstances and barriers to increasing the relevance of physical activity within the home. These barriers can then be addressed by adapting an exercise promotion program to the needs of this community. DISCUSSION/SIGNIFICANCE: Black women in under-resourced communities are more likely to be sedentary and have poor health. Exercise programs can be a powerful tool to address disparities and help prioritize health. The circumstances of women in public housing in Birmingham, AL, need community partners to adapt exercise engagement programs to meet environmental challenges.
Stroke-related tissue damage within lesioned brain areas is topologically non-uniform and has underlying tissue composition changes that may have important implications for rehabilitation. However, ...we know of no uniformly accepted, objective non-invasive methodology to identify pericavitational areas within the chronic stroke lesion. To fill this gap, we propose a novel magnetic resonance imaging (MRI) methodology to objectively quantify the lesion core and surrounding pericavitational perimeter, which we call tissue integrity gradation
T2w T1w ratio (TIGR). TIGR uses standard T1-weighted (T1w) and T2-weighted (T2w) anatomical images routinely collected in the clinical setting. TIGR maps are analyzed with relation to subject-specific gray matter and cerebrospinal fluid thresholds and binned to create a false colormap of tissue damage within the stroke lesion, and these are further categorized into low-, medium-, and high-damage areas. We validate TIGR by showing that the cerebral blood flow within the lesion reduces with greater tissue damage (
= 0.005). We further show that a significant task activity can be detected in pericavitational areas and that medium-damage areas contain a significantly lower magnitude of hemodynamic response function than the adjacent damaged areas (
< 0.0001). We also demonstrate the feasibility of using TIGR maps to extract multivariate brain-behavior relationships (
< 0.05) and show general agreement in location compared to binary lesion, T1w-only, and T2w-only maps but that the extent of brain behavior maps may depend on signal sensitivity as denoted by the sparseness coefficient (
< 0.0001). Finally, we show the feasibility of quantifying TIGR in early and late subacute stroke phases, where higher-damage areas were smaller in size (
= 0.002) and that lesioned voxels transition from lower to higher damage with increasing time post-stroke (
= 0.004). We conclude that TIGR is able to (1) identify tissue damage gradient within the stroke lesion across different post-stroke timepoints and (2) more objectively delineate lesion core from pericavitational areas wherein such areas demonstrate reasonable and expected physiological and functional impairments. Importantly, because T1w and T2w scans are routinely collected in the clinic, TIGR maps can be readily incorporated in clinical settings without additional imaging costs or patient burden to facilitate decision processes related to rehabilitation planning.
Cardiovascular disease (CVD) in the United States disproportionally affects people who are homeless. This disparity is a critical concern that needs to be addressed to improve the health of ...individuals who are homeless. The connections between a history of homelessness, i.e., its duration and frequency, and CVD risk are not well understood. The present study sought to investigate how a history of homelessness is correlated with CVD risk factors in a sample of homeless persons in the Deep South. This study recruited participants who were homeless from two local adult homeless shelters in Birmingham, AL. Participants (
= 61) underwent interviews, physical measurements, and a capillary blood draw. Their mean age was 47 years, and 82% were men. Results showed the duration of homelessness was positively associated with several CVD risk factors (diabetes mellitus, total cholesterol, and low-density lipoprotein). However, there was no significant association between frequency of homelessness and any CVD risk factors. To get the more accurate estimate of CVD risk in this population, future research should incorporate additional risk factors related to homelessness and seek to develop a robust strategy to collect an accurate history of homelessness.
► We compare ipsilateral motor activity across age groupings using fMRI and TMS. ► Groups consist of young adults, physically active elderly adults, and sedentary elderly adults. ► Physically active ...older adults show ipsilateral motor patterns similar to younger adults. ► Ipsilateral silent period inversely correlates with fMRI activity in ipsilateral motor cortex.
Aerobic exercise has been suggested to ameliorate aging-related decline in humans. Recently, evidence has indicated chronological aging is associated with decreases in measures of interhemispheric inhibition during unimanual movements, but that such decreases may be mitigated by long-term physical fitness. The present study investigated measures of ipsilateral (right) primary motor cortex activity during right-hand movements using functional magnetic resonance imaging and transcranial magnetic stimulation (TMS). Healthy, right-handed participant groups were comprised of 12 sedentary older adults, 12 physically active older adults, and 12 young adults. Active older adults and younger adults evidenced longer ipsilateral silent periods (iSP) and less positive BOLD of ipsilateral motor cortex (iM1) as compared to sedentary older adults. Across groups, duration of iSP from TMS was inversely correlated with BOLD activity in iM1 during unimanual movement. These findings suggest that increased physical activity may have a role in decreasing aging-related losses of interhemispheric inhibition.
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