Subregions of the inferior parietal lobule are affected in the progression to Alzheimer's disease

Department of Anatomy and Neurobiology, Boston University School of Medicine, Boston, MA 02118, USA.
Neurobiology of aging (Impact Factor: 5.01). 08/2010; 31(8):1304-11. DOI: 10.1016/j.neurobiolaging.2010.04.026
Source: PubMed


Changes in several regions within the brain have been associated with progression from healthy aging to Alzheimer's disease (AD), including the hippocampus, entorhinal cortex, and the inferior parietal lobule (IPL). In this study, the IPL was divided into three subregions: the gyrus, the banks of the sulcus, and the fundus to determine if these regions are independent of medial temporal regions in the progression of AD. Participants of the Alzheimer's disease Neuroimaging Initiative (Alzheimer's disease Neuroimaging initiative (ADNI); n = 54) underwent a structural magnetic resonance imaging (MRI) scan and neuropsychological examination, and were categorized as normal controls, mild cognitively impaired (MCI), or AD. FreeSurfer was initially used to identify the boundaries of the IPL. Each subregion was then manually traced based on FreeSurfer curvature intensities. Multivariate analyses of variance were used to compare groups. Results suggest that changes in thickness of the banks of the inferior parietal lobule are occurring early in the progression from normal to MCI, followed by changes in the gyrus and fundus, and these measures are related to neuropsychological performance.

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    • "For instance, Liang et al. (2012) showed that the AG connectivity with the DMN was significantly reduced in mild cognitive impairment. Another recent study also suggested that the subregions of the IPL were differentially affected in the progression from mild to severe Alzheimer's disease (Greene and Killiany, 2010). Characterizing the functional connectivity of these subregions would further our understanding of the functions of the IPL and shed new lights on how dysfunctions of the IPL may contribute to the clinical manifestations of these neurological processes. "
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    ABSTRACT: The human inferior parietal lobule (IPL) comprised the lateral bank of the intraparietal sulcus, angular gyrus and supramarginal gyrus, defined on the basis of anatomical landmarks and cytoarchitechtural organization of neurons. However, it is not clear whether the three areas represent functional subregions within the IPL. For instance, imaging studies frequently identified clusters of activities that cut across areal boundaries. Here, we used resting state functional magnetic resonance imaging (fMRI) data to examine how individual voxels within the IPL are best clustered according to their connectivity to the whole brain. The results identified a best estimate of 7 clusters which are hierarchically arranged as the anterior, middle, and posterior subregions. The anterior, middle, and posterior IPL are each significantly connected to the somatomotor areas, superior/middle/inferior frontal gyri, and regions of the default mode network. This functional segregation is supported by recent cytoarchitechtonics and tractography studies. IPL showed hemispheric differences in connectivity that accord with a predominantly left parietal role in tool use and language processing and a right parietal role in spatial attention and mathematical cognition. The functional clusters may also provide a more parsimonious and perhaps even accurate account of regional activations of the IPL during a variety of cognitive challenges, as reported in earlier fMRI studies.
    Brain Connectivity 12/2013; 4(1). DOI:10.1089/brain.2013.0191
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    • "Our findings of bilateral atrophy in the posterior cerebellum and in the inferior parietal lobule of the brain in the CAD group is novel given that these regions are usually preserved with age and atrophy has only been reported in a few dementia studies (Greene et al., 2010; Yoon et al., 2013). These studies linked poor performance on short-term memory and visuospatial tasks to GMV decline in either the cerebellum (Yoon et al., 2013) or the inferior parietal lobule (Greene et al., 2010), highlighting the known importance of both regions in neurocognitive integration. Taken together, these observations suggest that in older adults, cardiovascular disease can precipitate changes in normally stable regions of the brain. "
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    ABSTRACT: Cognitive function decline secondary to cardiovascular disease has been reported. However, little is known about the impact of coronary artery disease (CAD) on the aging brain macrostructure or whether exercise training, in the context of cardiovascular rehabilitation, can affect brain structure following a coronary event. This study employed voxel-based morphometry of high resolution structural MRI images to investigate; 1) changes in regional gray matter volume (GMV) in CAD patients compared to age-matched controls, and 2) the effects of a six-month exercise-based cardiovascular rehabilitation program on CAD-related GMV decline. Compared to controls, significant decreases in regional GMV were found in the superior, medial and inferior frontal gyrus; superior and inferior parietal gyrus; middle and superior temporal gyrus and in the posterior cerebellum of CAD patients. Cardiovascular rehabilitation was associated with the recovery of regional GMV in the superior frontal gyrus, superior temporal gyrus and posterior cerebellum of the CAD patients as well as the increase in GMV in the supplementary motor area. Total and regional GMV correlated with fitness level, defined by the maximal oxygen consumption (VO2max), at baseline but not after cardiovascular rehabilitation. This study demonstrates that cardiovascular disease can adversely affect age-related decline in GMV; and that these disease-related effects could be mitigated by moderate levels of exercise training as part of cardiovascular rehabilitation.
    Clinical neuroimaging 10/2013; 3:388-395. DOI:10.1016/j.nicl.2013.09.011 · 2.53 Impact Factor
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    • "Evidence indicates that the rIPL may become affected in MCI subjects that are more prone to convert to AD (Greene & Killiany, 2010). Our data are in line with these previous findings (Greene & Killiany, 2010; Turner & Spreng, 2012). "
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    ABSTRACT: Objectives. Aging is the major risk factor for Alzheimer Disease (AD) and Mild Cognitive Impairment (MCI). The aim of this study was to identify novel modifications of brain functional connectivity in MCI patients. MCI individuals were compared to healthy elderly subjects. Methods. We enrolled 37 subjects (age range 60–80 y.o.). Of these, 13 subjects were affected by MCI and 24 were age-matched healthy elderly control (HC). Subjects were evaluated with Mini Mental State Examination (MMSE), Frontal Assessment Battery (FAB), and prose memory (Babcock story) tests. In addition, with functional Magnetic Resonance Imaging (fMRI), we investigated resting state network (RSN) activities. Resting state (Rs) fMRI data were analyzed by means of Independent Component Analysis (ICA). Subjects were followed-up with neuropsychological evaluations for three years. Results. Rs-fMRI of MCI subjects showed increased intrinsic connectivity in the Default Mode Network (DMN) and in the Somatomotor Network (SMN). Analysis of the DMN showed statistically significant increased activation in the posterior cingulate cortex (PCC) and left inferior parietal lobule (lIPL). During the three years follow-up, 4 MCI subjects converted to AD. The subset of MCI AD-converted patients showed increased connectivity in the right Inferior Parietal Lobule (rIPL). As for SMN activity, MCI and MCI-AD converted groups showed increased level of connectivity in correspondence of the right Supramarginal Gyrus (rSG). Conclusions. Our findings indicate alterations of DMN and SMN activity in MCI subjects, thereby providing potential imaging-based markers that can be helpful for the early diagnosis and monitoring of these patients.
    PeerJ 08/2013; 1(1):e135. DOI:10.7717/peerj.135 · 2.11 Impact Factor
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