scholarly journals BRAIN FUNCTIONAL CONNECTIVITY IN OLDER ADULTS WITH MCI: DO FALLS MATTER?

2019 ◽  
Vol 3 (Supplement_1) ◽  
pp. S420-S420
Author(s):  
Anna R Egbert ◽  
Chun Liang Hsu ◽  
Rachel Crockett ◽  
Teresa Liu-Ambrose
Keyword(s):  
Older Adults ◽  
Functional Connectivity ◽  
Occipital Cortex ◽  
Structural Mri ◽  
Brain Regions ◽  
Cognitive Status ◽  
Metro Vancouver ◽  
Risk Of Falls ◽  
Brain Functional Connectivity

Abstract Older adults with mild cognitive impairment (MCI) are at an elevated risk of falls. We conducted a pilot longitudinal observational study to examine the natural course of brain intrinsic functional connectivity (FC) and cognitive function changes in association to falling history in older adults with MCI. 15 MCI participants (mean age 75.9, range 67-86) included 10 non-fallers and 5 fallers (minimum two falls in the previous 12 months with one in the last 6 months) from Metro Vancouver, BC, Canada. At study entry and 1-year follow-up, participants completed brain scanning session of structural MRI and resting state (RS) functional MRI, the Montreal Cognitive Assessment (MoCA), and the Mini Mental State Examination (MMSE). Results indicated an interaction between time (baseline vs. follow-up) and falls history on RS-FC in individuals with MCI (p<0.001). At 1-year follow-up, MCI non-fallers showed increased FC between frontal, parietal and occipital cortex (from baseline R=0.141 to follow-up R=0.321) and lack of decline on cognitive measures. Meanwhile, MCI fallers showed weakening of FC between those brain regions (from baseline R=0.314 to follow-up R=0.201) with simultaneous cognitive deterioration. Significant relationships between FC strength and cognitive status existed only at follow-up (R=0.525, p<0.05), suggesting that the triggered functional compensatory brain mechanisms in MCI non-fallers are not successfully executed in MCI fallers. Together, our pilot data suggest that older adults with MCI who fall show more advanced brain functional degradation with adjacent cognitive decline as compared to MCI individuals who do not fall.

scholarly journals Effects of amnesia on processing in the hippocampus and default mode network during a naturalistic memory task: a case study

2018 ◽  
Author(s):  
Christiane Oedekoven ◽  
James L. Keidel ◽  
Stuart Anderson ◽  
Angus Nisbet ◽  
Chris Bird
Keyword(s):  
Functional Connectivity ◽  
Episodic Memory ◽  
Memory Performance ◽  
Memory Task ◽  
Structural Mri ◽  
Brain Regions ◽  
Left Hippocampus ◽  
Cortical Regions ◽  
The Right ◽  
Encoding And Retrieval

Despite their severely impaired episodic memory, individuals with amnesia are able to comprehend ongoing events. Online representations of a current event are thought to be supported by a network of regions centred on the posterior midline cortex (PMC). By contrast, episodic memory is widely believed to be supported by interactions between the hippocampus and these cortical regions. In this MRI study, we investigated the encoding and retrieval of lifelike events (video clips) in a patient with severe amnesia likely resulting from a stroke to the right thalamus, and a group of 20 age-matched controls. Structural MRI revealed grey matter reductions in left hippocampus and left thalamus in comparison to controls. We first characterised the regions activated in the controls while they watched and retrieved the videos. There were no differences in activation between the patient and controls in any of the regions. We then identified a widespread network of brain regions, including the hippocampus, that were functionally connected with the PMC in controls. However, in the patient there was a specific reduction in functional connectivity between the PMC and a region of left hippocampus when both watching and attempting to retrieve the videos. A follow up analysis revealed that in controls the functional connectivity between these regions when watching the videos was correlated with memory performance. Taken together, these findings support the view that the interactions between the PMC and the hippocampus enable the encoding and retrieval of multimodal representations of the contents of an event.

Estimation of Cognitive Plasticity in Old Adults Using Dynamic Assessment Techniques

2009 ◽  
Vol 8 (1) ◽  
pp. 38-51 ◽  
Author(s):  
Elena Navarro ◽  
María Dolores Calero
Keyword(s):  
Older Adults ◽  
Cognitive Functioning ◽  
Dynamic Assessment ◽  
Cognitive Status ◽  
Diagnostic Utility ◽  
Old Adults ◽  
Age Related ◽  
Assessment Techniques ◽  
Cognitive Plasticity

In recent years, research has provided extensive data concerning the use, utility, and appropriateness of dynamic assessment techniques as a way of determining cognitive plasticity in old adults. Current research in this area is focused on three principle lines of investigation: (a) determining neurological correlates of cognitive plasticity evaluated through dynamic assessment techniques; (b) establishing the diagnostic utility of such procedures; and (c) analyzing age-related limits with regard to quantity and domains of plasticity. In this context, the present study was undertaken using a sample of 274 older adults, who were evaluated through two dynamic assessment techniques and one cognitive functioning screening test over a period of 3 consecutive years. Results show differences in plasticity related to both age and cognitive status. The study also demonstrates the capacity of plasticity to predict maintenance and decline in a follow-up period of 3 years.

scholarly journals On the role of the corpus callosum in interhemispheric functional connectivity in humans

2017 ◽  
Vol 114 (50) ◽  
pp. 13278-13283 ◽  
Author(s):  
Jarod L. Roland ◽  
Abraham Z. Snyder ◽  
Carl D. Hacker ◽  
Anish Mitra ◽  
Joshua S. Shimony ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Corpus Callosum ◽  
Parietal Lobe ◽  
Brain Regions ◽  
Resting State Functional Connectivity ◽  
Limited Sample ◽  
Temporal Correlations ◽  
Before And After

Resting state functional connectivity is defined in terms of temporal correlations between physiologic signals, most commonly studied using functional magnetic resonance imaging. Major features of functional connectivity correspond to structural (axonal) connectivity. However, this relation is not one-to-one. Interhemispheric functional connectivity in relation to the corpus callosum presents a case in point. Specifically, several reports have documented nearly intact interhemispheric functional connectivity in individuals in whom the corpus callosum (the major commissure between the hemispheres) never develops. To investigate this question, we assessed functional connectivity before and after surgical section of the corpus callosum in 22 patients with medically refractory epilepsy. Section of the corpus callosum markedly reduced interhemispheric functional connectivity. This effect was more profound in multimodal associative areas in the frontal and parietal lobe than primary regions of sensorimotor and visual function. Moreover, no evidence of recovery was observed in a limited sample in which multiyear, longitudinal follow-up was obtained. Comparison of partial vs. complete callosotomy revealed several effects implying the existence of polysynaptic functional connectivity between remote brain regions. Thus, our results demonstrate that callosal as well as extracallosal anatomical connections play a role in the maintenance of interhemispheric functional connectivity.

scholarly journals Functional network integrity presages cognitive decline in preclinical Alzheimer disease

Neurology ◽  
2017 ◽  
Vol 89 (1) ◽  
pp. 29-37 ◽  
Author(s):  
Rachel F. Buckley ◽  
Aaron P. Schultz ◽  
Trey Hedden ◽  
Kathryn V. Papp ◽  
Bernard J. Hanseeuw ◽  
...  
Keyword(s):  
Older Adults ◽  
Functional Connectivity ◽  
Alzheimer Disease ◽  
Cognitive Decline ◽  
Cognitive Networks ◽  
Rate Of Change ◽  
Control Networks ◽  
Clinically Normal ◽  
And Control

Objective:To examine the utility of resting-state functional connectivity MRI (rs-fcMRI) measurements of network integrity as a predictor of future cognitive decline in preclinical Alzheimer disease (AD).Methods:A total of 237 clinically normal older adults (aged 63–90 years, Clinical Dementia Rating 0) underwent baseline β-amyloid (Aβ) imaging with Pittsburgh compound B PET and structural and rs-fcMRI. We identified 7 networks for analysis, including 4 cognitive networks (default, salience, dorsal attention, and frontoparietal control) and 3 noncognitive networks (primary visual, extrastriate visual, motor). Using linear and curvilinear mixed models, we used baseline connectivity in these networks to predict longitudinal changes in preclinical Alzheimer cognitive composite (PACC) performance, both alone and interacting with Aβ burden. Median neuropsychological follow-up was 3 years.Results:Baseline connectivity in the default, salience, and control networks predicted longitudinal PACC decline, unlike connectivity in the dorsal attention and all noncognitive networks. Default, salience, and control network connectivity was also synergistic with Aβ burden in predicting decline, with combined higher Aβ and lower connectivity predicting the steepest curvilinear decline in PACC performance.Conclusions:In clinically normal older adults, lower functional connectivity predicted more rapid decline in PACC scores over time, particularly when coupled with increased Aβ burden. Among examined networks, default, salience, and control networks were the strongest predictors of rate of change in PACC scores, with the inflection point of greatest decline beyond the fourth year of follow-up. These results suggest that rs-fcMRI may be a useful predictor of early, AD-related cognitive decline in clinical research settings.

scholarly journals Reorganization of Brain Functional Connectivity Network and Vision Restoration Following Combined tACS-tDCS Treatment After Occipital Stroke

2021 ◽  
Vol 12 ◽  
Author(s):  
Jiahua Xu ◽  
Zheng Wu ◽  
Andreas Nürnberger ◽  
Bernhard A. Sabel
Keyword(s):  
Visual Field ◽  
Functional Connectivity ◽  
Temporal Lobe ◽  
Brain Stimulation ◽  
Occipital Lobe ◽  
Clustering Coefficient ◽  
Alpha Band ◽  
Delta Band ◽  
Brain Functional Connectivity

Objective: Non-invasive brain stimulation (NIBS) is already known to improve visual field functions in patients with optic nerve damage and partially restores the organization of brain functional connectivity networks (FCNs). However, because little is known if NIBS is effective also following brain damage, we now studied the correlation between visual field recovery and FCN reorganization in patients with stroke of the central visual pathway.Method: In a controlled, exploratory trial, 24 patients with hemianopia were randomly assigned to one of three brain stimulation groups: transcranial direct current stimulation (tDCS)/transcranial alternating current stimulation (tACS) (ACDC); sham tDCS/tACS (AC); sham tDCS/sham tACS (Sham), which were compared to age-matched controls (n = 24). Resting-state electroencephalogram (EEG) was collected at baseline, after 10 days stimulation and at 2 months follow-up. EEG recordings were analyzed for FCN measures using graph theory parameters, and FCN small worldness of the network and long pairwise coherence parameter alterations were then correlated with visual field performance.Result: ACDC enhanced alpha-band FCN strength in the superior occipital lobe of the lesioned hemisphere at follow-up. A negative correlation (r = −0.80) was found between the intact visual field size and characteristic path length (CPL) after ACDC with a trend of decreased alpha-band centrality of the intact middle occipital cortex. ACDC also significantly decreased delta band coherence between the lesion and the intact occipital lobe, and coherence was enhanced between occipital and temporal lobe of the intact hemisphere in the low beta band. Responders showed significantly higher strength in the low alpha band at follow-up in the intact lingual and calcarine cortex and in the superior occipital region of the lesioned hemisphere.Conclusion: While ACDC decreases delta band coherence between intact and damaged occipital brain areas indicating inhibition of low-frequency neural oscillations, ACDC increases FCN connectivity between the occipital and temporal lobe in the intact hemisphere. When taken together with the lower global clustering coefficient in responders, these findings suggest that FCN reorganization (here induced by NIBS) is adaptive in stroke. It leads to greater efficiency of neural processing, where the FCN requires fewer connections for visual processing.

scholarly journals Functional Connectivity of Nucleus Accumbens and Medial Prefrontal Cortex With Other Brain Regions During Early-Abstinence Is Associated With Alcohol Dependence and Relapse: A Resting-Functional Magnetic Resonance Imaging Study

2021 ◽  
Vol 12 ◽  
Author(s):  
Xia Yang ◽  
Ya-jing Meng ◽  
Yu-jie Tao ◽  
Ren-hao Deng ◽  
Hui-yao Wang ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Prefrontal Cortex ◽  
Magnetic Resonance ◽  
Functional Connectivity ◽  
Brain Regions ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Anterior Cortex ◽  
The Right

Background: Alcohol dependence (AD) is a chronic recurrent brain disease that causes a heavy disease burden worldwide, partly due to high relapse rates after detoxification. Verified biomarkers are not available for AD and its relapse, although the nucleus accumbens (NAc) and medial prefrontal cortex (mPFC) may play important roles in the mechanism of addiction. This study investigated AD- and relapse-associated functional connectivity (FC) of the NAc and mPFC with other brain regions during early abstinence.Methods: Sixty-eight hospitalized early-abstinence AD male patients and 68 age- and education-matched healthy controls (HCs) underwent resting-functional magnetic resonance imaging (r-fMRI). Using the NAc and mPFC as seeds, we calculated changes in FC between the seeds and other brain regions. Over a follow-up period of 6 months, patients were measured with the Alcohol Use Disorder Identification Test (AUDIT) scale to identify relapse outcomes (AUDIT ≥ 8).Results: Thirty-five (52.24%) of the AD patients relapsed during the follow-up period. AD displayed lower FC of the left fusiform, bilateral temporal superior and right postcentral regions with the NAc and lower FC of the right temporal inferior, bilateral temporal superior, and left cingulate anterior regions with the mPFC compared to controls. Among these FC changes, lower FC between the NAc and left fusiform, lower FC between the mPFC and left cingulate anterior cortex, and smoking status were independently associated with AD. Subjects in relapse exhibited lower FC of the right cingulate anterior cortex with NAc and of the left calcarine sulcus with mPFC compared to non-relapsed subjects; both of these reductions in FC independently predicted relapse. Additionally, FC between the mPFC and right frontal superior gyrus, as well as years of education, independently predicted relapse severity.Conclusion: This study found that values of FC between selected seeds (i.e., the NAc and the mPFC) and some other reward- and/or impulse-control-related brain regions were associated with AD and relapse; these FC values could be potential biomarkers of AD or for prediction of relapse. These findings may help to guide further research on the neurobiology of AD and other addictive disorders.

scholarly journals Brain Functional Connectivity Changes in Middle-Aged Hong Chuan Tai Chi Players

2021 ◽  
Author(s):  
Zhenguo Shi ◽  
Lei Xu ◽  
Hui Xie ◽  
Xiangliang Zhang ◽  
Qiang He
Keyword(s):  
Prefrontal Cortex ◽  
Functional Connectivity ◽  
Motor Cortex ◽  
Tai Chi ◽  
Cerebral Oxygenation ◽  
Occipital Cortex ◽  
Middle Aged ◽  
Left And Right ◽  
Global Cognition ◽  
Brain Functional Connectivity

Abstract Tai Chi has been shown an effective strategy to improve cognitive function in older populations while the underlying mechanism remains unclear. This cross-sectional study was performed to examine the brain functional connectivity changes in middle-aged Hong Chuan Tai Chi practitioners. The changes in cerebral oxygenation were measured by functional near-infrared spectroscopy. NIRS signals were obtained from left and right prefrontal cortex, motor cortex and occipital cortex in 18 Hong chuan Tai Chi practitioners (age:55.78 ± 2.64y) and 22 demographically matched healthy Tai Chi-naïve controls (age:54.69 ± 3.10y). Global cognition was measured by the Montreal Cognitive Assessment Scale, and spontaneous oscillations in cerebral oxygenation between three cortexes in five frequency intervals (I, 0.6-2Hz; II, 0.145-0.6Hz; III, 0.052-0.145Hz; IV, 0.021-0.052Hz; V, 0.0095-0.021Hz) was analyzed by wavelet phase coherence. Compared with age-matched Tai Chi-naïve controls, Hong Chuan Tai Chi practitioners had better global cognition, showed higher functional connectivity between left and right prefrontal cortex, motor cortex, occipital cortex in intervals I, III, VI and V. These findings showed that middle-aged Hong Chuan Tai Chi practitioners had higher functional connectivity between prefrontal cortex, motor cortex and occipital cortex, as well as the coordination of left and right brain, which maybe the contributing factors to higher global cognition.

Regional Hypoperfusion Predicts Decline in Everyday Functioning at Three-Year Follow-Up in Older Adults without Dementia

2020 ◽  
Vol 77 (3) ◽  
pp. 1291-1304
Author(s):  
Danielle L. Sanchez ◽  
Kelsey R. Thomas ◽  
Emily C. Edmonds ◽  
Mark W. Bondi ◽  
Katherine J. Bangen ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Older Adults ◽  
Alzheimer's Disease ◽  
Cerebral Metabolism ◽  
Functional Decline ◽  
Amyloid Β ◽  
Cognitive Status ◽  
White Matter Hyperintensity ◽  
Everyday Functioning

Background: Increasing evidence indicates that cerebrovascular dysfunction may precede cognitive decline in aging and Alzheimer’s disease (AD). Reduced cerebral blood flow (CBF) is associated with cognitive impairment in older adults. However, less is known regarding the association between CBF and functional decline, and whether CBF predicts functional decline beyond cerebrovascular and metabolic risk factors. Objective: To examine the association between regional CBF and functional decline in nondemented older adults. Method: One hundred sixty-six (N = 166) participants without dementia from the Alzheimer’s Disease Neuroimaging Initiative underwent neuropsychological testing and neuroimaging. Pulsed arterial spin labeling magnetic resonance imaging was acquired to quantify resting CBF. Everyday functioning was measured using the Functional Assessment Questionnaire at baseline and annual follow-up visit across three years. Results: Adjusting for age, education, sex, cognitive status, depression, white matter hyperintensity volume, cerebral metabolism, and reference (precentral) CBF, linear mixed effects models showed that lower resting CBF at baseline in the medial temporal, inferior temporal, and inferior parietal lobe was significantly associated with accelerated decline in everyday functioning. Results were similar after adjusting for conventional AD biomarkers, including cerebrospinal fluid (CSF) amyloid-β (Aβ) and hyperphosphorylated tau (p-tau) and apolipoprotein E (APOE) ɛ4 positivity. Individuals who later converted to dementia had lower resting CBF in the inferior temporal and parietal regions compared to those who did not. Conclusion: Lower resting CBF in AD vulnerable regions including medial temporal, inferior temporal, and inferior parietal lobes predicted faster rates of decline in everyday functioning. CBF has utility as a biomarker in predicting functional declines in everyday life and conversion to dementia.

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