Amplitude Of Low-frequency Fluctuation Changes Research Articles

Intervention-induced enhancement in intrinsic brain activity in healthy older adults

This study examined the effects of a multimodal intervention on spontaneous brain activity in healthy older adults. Seventeen older adults received a six-week intervention that consisted of cognitive training, Tai Chi exercise, and group counseling, while 17 older adults in a control group attended health knowledge lectures. The intervention group demonstrated enhanced memory and social support compared to the control group. The amplitude of low frequency fluctuations (ALFF) in the middle frontal gyrus, superior frontal gyrus, and anterior cerebellum lobe was enhanced for the intervention group, while the control group showed reduced ALFF in these three regions. Moreover, changes in trail-making performance and well-being could be predicted by the intervention-induced changes in ALFF. Additionally, individual differences in the baseline ALFF were correlated with intervention-related changes in behavioral performance. These findings suggest that a multimodal intervention is effective in improving cognitive functions and well-being and can induce functional changes in the aging brain. The study extended previous training studies by suggesting resting-state ALFF as a marker of intervention-induced plasticity in older adults.

Aggravated Cognitive and Brain Functional Impairment in Mild Cognitive Impairment Patients with Type 2 Diabetes: A Resting-State Functional MRI Study

Type 2 diabetes mellitus is a metabolic disorder and a risk factor for dementia and mild cognitive impairment (MCI), which could also increase the risk of progression from MCI to dementia. The present study evaluated the spontaneous neuronal activity of 31 patients with MCI using resting-state functional MRI. The patients were divided into two groups (17 MCI patients without diabetes, and 14 patients with type 2 diabetes who were considered as the MCI-DM group) and 17 well-matched healthy controls were also recruited. The amplitude of low-frequency fluctuations (ALFF) of spontaneous blood oxygen level dependent signals was then applied to assess neuroimaging changes. To further investigate the impact of type 2 diabetes on cognition, the correlation of ALFF and the neuropsychological tests for the MCI-DM and MCI group were calculated. MCI-DM patients showed diffused ALFF changes in a variety of brain regions that were significantly related to cognitive performance, including the frontal lobe, the temporal lobe, the hippocampus, the amygdala, and the precuneus during a resting state; whereas, the alterations were much less pronounced in the MCI patients without diabetes. These findings provide new insights into understanding essential of diabetes mellitus and may help to clarify the relationship between diabetes mellitus and dementia.

Altered Amplitude of Low-frequency Fluctuations in Early and Late Mild Cognitive Impairment and Alzheimer's Disease

Previous studies have shown that the strength of the low frequency fluctuation in the medial-line brain areas are abnormally reduced in mild cognitive impairment (MCI) and Alzheimer's disease (AD) patients. The purpose of this study was to explore the functional brain changes in early MCI (EMCI) and late MCI (LMCI) patients by measuring the amplitude of the blood oxygenation level dependent (BOLD) functional MRI (fMRI) signals at rest. 35 elderly normal controls (NC), 24 EMCI, 29 LMCI, and 14 AD patients from the Alzheimer's Disease Neuroimaging Initiative (ADNI2) were included in this study. Resting state fMRI and 3D structural MRI data were acquired. The spatial patterns of spontaneous brain activity were measured by examining the amplitude of low-frequency fluctuations (ALFF) of BOLD signal during rest. A one-way analysis of variance (ANOVA) was then performed on ALFF maps, with age, sex and regional atrophy as covariates. There were widespread ALFF differences among the four groups. As compared with controls, AD, LMCI and EMCI patients showed decreased ALFF mainly in the posterior cingulate cortex, precuneus, right lingual gyrus and thalamus (with a linear trend: NC>EMCI>LMCI>AD), while there was increased activity in the right parahippocampal gyrus (with a linear trend: NC<EMCI<LMCI<AD). Additionally, we also showed that many regions with ALFF changes had significant correlations with the cognitive performance as measured by mini-mental state examination scores (MMSE) and the emotion states as measured by Geriatric Depression Scale (GD scale) for EMCI, LMCI and AD patients, but not for controls. Our results indicated that the significantly altered ALFF activities can be detected at EMCI stage, independent of age, sex and regional atrophy. The present study thus suggests ALFF abnormalities as a potential biomarker for the early diagnosis of AD and further provides insights into biological mechanisms of the diseases.

Structural and Functional Brain Changes in the Default Mode Network in Subtypes of Amnestic Mild Cognitive Impairment

Various amnestic mild cognitive impairment (aMCI) subtypes have been identified as single domain (SD) or multiple domain (MD), with differential probabilities of progression to Alzheimer disease (AD). Detecting the differences in the alterations in gray matter (GM) and intrinsic brain activity between the subtypes of aMCI help to understand their pathophysiological mechanisms and was conducive to construct such potential biomarkers to monitor the progression of aMCI. In all, 22 normal controls (NCs), 18 patients with SD-aMCI, and 17 patients with MD-aMCI participated in the study. The amplitude of low-frequency fluctuations (ALFFs) during rest represented intrinsic brain activity. Voxel-based morphometry analysis was used to measure the GM volume. The MD-aMCI showed reduced GM in hippocampus (Hip), parahippocampal gyrus (PHG), and other regions than SD-aMCI. The SD-aMCI had reduced GM only in Hip and PHG than in NC. The MD-aMCI showed decreased ALFF in posterior cingulate cortex (PCC) and precuneus and increased ALFF in anterior cingulate cortex (ACC), PHG, and Hip compared with both SD-aMCI and NC. However, no ALFF difference was found between SD-aMCI and NC. Neuropsychological measures were correlated with ALFF in PCC and ACC only in the MD-aMCI. Patients with MD-aMCI displayed more severe GM atrophy and ALFF changes than patients with SD-aMCI. The results suggested that aMCI is heterogeneous and that MD-aMCI may be a prodromal stage which is more close to AD.

Fractional amplitude of low-frequency fluctuation changes in monkeys with spinal cord injury: A resting-state fMRI study

PurposeAlthough functional magnetic resonance imaging (fMRI) has revealed that spinal cord injury (SCI) causes anomalous changes in task-induced brain activation, its effect during the resting state remains unclear. The aim of this study is to explore the changes of the brain resting-state function in non-human primates with unilateral SCI. Materials and methodsEleven adult female rhesus monkeys were subjected to resting-state fMRI: five with unilateral thoracic SCI and six healthy monkeys, to obtain the fractional amplitude of low-frequency fluctuations (fALFF) of the blood oxygenation level-dependent (BOLD) contrast signal to determine the influence of SCI on the cerebral resting-state function. ResultsThe SCI-induced fALFF vary significantly in several encephalic regions, including the left cerebellum, the left thalamus, the right lateral geniculate nucleus, the right superior parietal lobule, and the posterior cingulate gyrus. ConclusionAnalysis of the resting-state fMRI provides evidence of abnormal spontaneous brain activations in primates with SCI, which may help us understand the pathophysiologic mechanisms underlying the changes in neural plasticity in the central nervous system after SCI.

Spontaneous brain activity in adult patients with moyamoya disease: a resting-state fMRI study

Adult patients with moyamoya disease (MMD) are reported to suffer from vascular cognitive impairment (VCI), including considerable impairment of executive function/attention. The spatial pattern of functional brain activity in adult MMD patients with VCI has not been studied before and can be measured by examining the amplitude of low-frequency fluctuations (ALFF) of blood oxygen level-dependent functional magnetic resonance imaging (BOLD fMRI) during rest. Twenty-three adult patients with MMD were recruited to participate in this study, including 11 with VCI and 12 without VCI (NonVCI), as well as 22 healthy young adults (normal control, NC). Widespread differences in ALFF were observed between the VCI/NonVCI and NC groups in such regions as the frontal, parietal and temporal gyri, with parts of the frontal gyrus, such as the anterior cingulate cortex (ACC) and the right supplemental motor area (SMA), showing significant differences in ALFF. It is worth to note that regions such as the parietal gyrus, the right superior frontal gyrus (SFG), the right superior temporal gyrus (STG) and the left caudate nucleus (CN) exhibited significant changes in ALFF during the progressive cognitive decline of MMD. Taken together, our results demonstrate that MMD exhibits a specific intrinsic pattern of ALFF and that this pattern changes with the progression of cognitive decline, providing insight into the pathophysiological nature of this disease.

Fractional amplitude of low-frequency fluctuation changes in functional dyspepsia: A resting-state fMRI study

Recently, there is an increasing interest in the study of the role of brain dysfunction in the pathogenesis of symptoms of functional dyspepsia (FD). More specifically, abnormal brain activities in patients with FD during the resting state have been proven by several positron emission tomography (PET) studies. Resting-state functional magnetic resonance imaging (fMRI) is also a valuable tool in investigating spontaneous brain activity abnormalities in pathological conditions. In the present study, we examined the amplitude of low-frequency fluctuations (ALFF) and fractional (f)ALFF changes in patients with FD by using fMRI. Twenty-nine patients with FD and sixteen healthy controls participated in this study. Between-group differences in ALFF/fALFF were examined using a permutation-based nonparametric test after accounting for the gender and age effects. The results revealed a significant between-group difference in fALFF but not in ALFF in multiple brain regions including the right insula, brainstem and cerebellum. Seed-based resting-state functional connectivity analysis revealed that FD patients have increased correlations between the right cerebellum and multiple brain regions including the bilateral brainstem, bilateral cerebellum, bilateral thalamus, left para-/hippocampus, left pallidum and left putamen. Furthermore, fLAFF values in the right insula were positively correlated with the severity of the disease. These findings have provided further evidence of spontaneous brain activity abnormalities in FD patients which might contribute to our understanding of the pathophysiology of the disease.

Abnormal baseline brain activity in low-grade hepatic encephalopathy: A resting-state fMRI study

Resting-state functional magnetic resonance imaging (fMRI) has been used to detect the alterations of spontaneous neuronal activity in various neuropsychiatric diseases, but rarely in low-grade hepatic encephalopathy (HE), a common neuropsychiatric complication of liver cirrhosis. We conducted a resting-state fMRI in 19 healthy controls, 18 cirrhotic patients without HE, and 22 cirrhotic patients with low-grade HE. The amplitude of low-frequency fluctuations (ALFF) of fMRI signal was computed to measure the spontaneous neuronal activity. Several regions showing significant ALFF differences among three groups were the precuneus, occipital lobe, left frontal lobe and anterior/middle cingulate cortex, and left cerebellum posterior lobe. Compared to controls or patients without HE, patients with low-grade HE showed decreased ALFF in the precuneus and adjacent cuneus, visual cortex, and left cerebellum posterior lobe. Compared to controls, patients with low-grade HE showed higher ALFF in both cortical and subcortical regions, including the right middle cingulate gyrus, and left anterior/middle cingulate gyrus, inferior frontal gyrus, insula lobe, parahippocampal gyrus, middle temporal gyrus and lentiform nucleus; compared to patients without HE, patients with low-grade HE showed higher ALFF in the left medial frontal gyrus and anterior cingulate gyrus, bilateral superior frontal gyrus, and right middle frontal gyrus. Moreover, correlations between ALFF changes and poor neurocognitive performances were found in patients with low-grade HE. These results suggested the existence of aberrant brain activity at the baseline state in low-grade HE, which may be implicated in the neurological pathophysiology underlying HE.

Spatial patterns of intrinsic brain activity in mild cognitive impairment and alzheimer's disease: A resting‐state functional MRI study

We used resting-state functional MRI to investigate spatial patterns of spontaneous brain activity in 22 healthy elderly subjects, as well as 16 mild cognitive impairment (MCI) and 16 Alzheimer's disease (AD) patients. The pattern of intrinsic brain activity was measured by examining the amplitude of low-frequency fluctuations (ALFF) of blood oxygen level dependent signal during rest. There were widespread ALFF differences among the three groups throughout the frontal, temporal, and parietal cortices. Both AD and MCI patients showed decreased activity mainly in the medial parietal lobe region and lentiform nucleus, while there was increased activity in the lateral temporal regions and superior frontal and parietal regions as compared with controls. Compared with MCI, the AD patients showed decreased activity in the medial prefrontal cortex and increased activity in the superior frontal gyrus and inferior and superior temporal gyri. Specifically, the most significant ALFF differences among the groups appeared in the posterior cingulate cortex, with a reduced pattern of activity when comparing healthy controls, MCI, and AD patients. Additionally, we also showed that the regions with ALFF changes had significant correlations with the cognitive performance of patients as measured by mini-mental state examination scores. Finally, while taking gray matter volume as covariates, the ALFF results were approximately consistent with those without gray matter correction, implying that the functional analysis could not be explained by regional atrophy. Together, our results demonstrate that there is a specific pattern of ALFF in AD and MCI, thus providing insights into biological mechanisms of the diseases.