Functional relevant loss of long association fibre tracts integrity in early Alzheimer's disease

Fellgiebel, Andreas; Schermuly, Ingrid; Gerhard, Alexander; Keller, Isabel; Albrecht, Juliane; Weibrich, Carsten; Müller, Matthias J.; Stoeter, P.

doi:10.1016/j.neuropsychologia.2007.12.010

Cited by 83 publications

(76 citation statements)

References 53 publications

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“…Furthermore, the decline in the corpus callosum, whose fibers connect both hemispheres, is consistent with atrophy of these areas due to grey matter declines on the cortex (Hampel et al, 2000;Hensel et al, 2002;Teipel et al, 2003;Teipel et al, 2002;Teipel et al, 1998;Teipel et al, 1999). It was found that left cingulum fibers, which connect the anterior thalamus, the cortical cingulum, and the association cortices in the frontal, temporal and parietal cortices and the hippocampus to each other, were correlated with free recall, verbal recognition and Boston Naming test performance in AD patients (Fellgiebel et al, 2008). The various regions that the cingulum fibers connect have been shown to be involved in the various tasks of memory such as encoding (in the hippocampus), retrieval and recognition (in the posterior cingulate, the retrosplenial cortex, and posterior and medial parietal cortex).…”

Section: Connectivity Dysfunction Due To Changes In White Mattermentioning

confidence: 72%

Assessing neuronal networks: Understanding Alzheimer's disease

Bokde

Ewers

Hampel

2009

Progress in Neurobiology

112

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Findings derived from neuroimaging of the structural and functional organization of the human brain have led to the widely supported hypothesis that neuronal networks of temporally coordinated brain activity across different regional brain structures underpin cognitive function. Failure of integration within a network leads to cognitive dysfunction. The current discussion on Alzheimer's disease (AD) argues that it presents in part a disconnection syndrome. Studies using functional magnetic resonance imaging, positron emission tomography and electroencephalography demonstrate that synchronicity of brain activity is altered in AD and correlates with cognitive deficits. Moreover, recent advances in diffusion tensor imaging have made it possible to track axonal projections across the brain, revealing substantial regional impairment in fiber-tract integrity in AD. Accumulating evidence points towards a network breakdown reflecting disconnection at both the structural and functional system level. The exact relationship among these multiple mechanistic variables and their contribution to cognitive alterations and ultimately decline is yet unknown.Focused research efforts aimed at the integration of both function and structure hold great promise not only in improving our understanding of cognition but also of its characteristic progressive metamorphosis in complex chronic neurodegenerative disorders such as AD. Page 3 of 50A c c e p t e d M a n u s c r i p t 3 IntroductionFunctional neuroimaging studies in humans and animals suggest that particular brain regions are necessary for specific cognitive functions. The activations of different brain regions, however, do not appear to occur independently from each other but may occur in a sequential spatio-temporally ordered fashion Murphy et al., 1993). The involved regions integrate into a large-scale network which forms the basis of cognition and closely relates to its complex underlying systemic structural architecture (Horwitz et al., 2005;Lee et al., 2006;Luria, 1973;McIntosh, 2004;Rogers et al., 2007). For example, successful associative learning has been shown to correlate with a change in the effective connectivity, i.e., the influence of activation of one brain region onto another, within a specific neuronal network (Buchel et al., 1999). From the neuroanatomical perspective, connectivity of brain activity is predicted to be confined towards pathways of neuroanatomical connections between specific brain regions (Greicius et al., 2008;Toosy et al., 2004). These neuroanatomical constraints allow generating useful predictive models, specific working hypotheses concerning the effect of localized lesions on specific network functions in complex chronically progressive neurodegenerative system disorders such as Alzheimer's disease (AD).Thus a failure of the regions of a network to interact at a high level of coordination may underpin the cognitive disorders which are present in AD. The failure of network function may be due to interaction failure among the region...

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Section: Connectivity Dysfunction Due To Changes In White Mattermentioning

confidence: 72%

Assessing neuronal networks: Understanding Alzheimer's disease

Bokde

Ewers

Hampel

2009

Progress in Neurobiology

112

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“…Such an association has been demonstrated in different degenerative disorders such as Parkinson disease and Alzheimer disease. 23,39 It suggests a role of neurodegeneration in cognitive deficits seen in ET. Neuropathologic studies also provide evidence of neurodegeneration in ET.…”

Section: Discussionmentioning

confidence: 99%

White Matter Correlates of Cognitive Impairment in Essential Tremor

Bhalsing¹,

Kumar

Saini

et al. 2014

AJNR Am J Neuroradiol

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“…However, there are a number of studies that have failed to find increased MD in these regions in AD. For example, no significant increase in MD was reported in ROI investigations of the frontal lobe [41,80], parietal lobe [80], occipital lobe [14,15,32,80], corpus callosum [32,41,52,92] and posterior cingulum [30,52].…”

Section: Mean Diffusivity In Ad and MCImentioning

confidence: 97%

“…Increases in MD have been reported in the frontal lobes [68], temporal lobe [32] including the hippocampus [32] and entorhinal cortex [68], parietal lobe [80], occipital lobe [32,68], and posterior cingulum [31,92]. As with the studies of MD in AD, there are studies that do not find increased MD in individuals with MCI in some or all of these regions (e.g., [30,55,80]). Additionally, there are a few studies demonstrating an increase in MD in patients with AD, but no increase in individuals with MCI [30,80], suggesting a lesser pathological burden in the MCI patients.…”

Section: Mean Diffusivity In Ad and MCImentioning

confidence: 99%

“…As with the studies of MD in AD, there are studies that do not find increased MD in individuals with MCI in some or all of these regions (e.g., [30,55,80]). Additionally, there are a few studies demonstrating an increase in MD in patients with AD, but no increase in individuals with MCI [30,80], suggesting a lesser pathological burden in the MCI patients.…”

Section: Mean Diffusivity In Ad and MCImentioning

confidence: 99%

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Diffusion Tensor Imaging in Alzheimer’s Disease and Mild Cognitive Impairment

Stebbins

Murphy

2009

Behavioural Neurology

193

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Abstract. Structural magnetic resonance imaging (MRI) studies of Alzheimer's disease and mild cognitive impairment (MCI) have focused on the hippocampus and entorhinal cortex; gray matter structures in the medial temporal lobe. Few studies have investigated the integrity of white matter in patients with AD or MCI. Diffusion tensor imaging (DTI) is a MRI technique that allows for the interrogation of the microstructural integrity of white matter. Based on increases in translational diffusion (mean diffusivity: MD) and decreases directional diffusion (fractional anisotropy: FA) damage to white matter can be assessed. Studies have identified regions of increased MD and decreased FA in patients with AD and MCI in all lobes of the brain, as well as medial temporal lobe structures including the hippocampus, entorhinal cortex and parahippocampal white matter. The pattern of white matter integrity disruption tends to follow an anterior to posterior gradient with greater damage noted in posterior regions in AD and MCI. Recent studies have exploited inter-voxel directional similarities to develop models of white matter pathways, and have used these models to assess the integrity of inter-cerebral connections. Particular focus has been applied to the parahippocampal white matter (including the perforant path) and the posterior cingulum. Although many studies have found DTI indicators of impaired white matter in AD and MCI, other studies have failed to detect any differences in MD or FA between the groups, demonstrating the need for large replicative studies. DTI is an evolving technique and advances in its application ought to provide new insights into AD and MCI.

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Functional relevant loss of long association fibre tracts integrity in early Alzheimer's disease

Cited by 83 publications

References 53 publications

Assessing neuronal networks: Understanding Alzheimer's disease

Assessing neuronal networks: Understanding Alzheimer's disease

White Matter Correlates of Cognitive Impairment in Essential Tremor

Diffusion Tensor Imaging in Alzheimer’s Disease and Mild Cognitive Impairment

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