Functional abnormalities of the visual processing system in subjects with mild cognitive impairment: An fMRI study

Bokde, Arun L.W.; Lopez-Bayo, Patricia; Born, Christine; Dong, Wei; Meindl, Thomas; Leinsinger, Gerda; Teipel, Stefan J.; Faltraco, Frank; Reiser, Maximilian; Möller, Hans‐Jürgen; Hampel, Harald

doi:10.1016/j.pscychresns.2007.08.013

Cited by 54 publications

(42 citation statements)

References 39 publications

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“…In an encoding task with visual stimuli, the aMCI subjects had higher activation in right parahippocampal gyrus compared to HC and those that showed the greatest activation in this region within the aMCI group, had the greater cognitive decline within the following 2.5 years [21]. Compensatory mechanisms have been found not only in memory but also in a visual perception task in MCI subjects [22]. In addition in a study of AD patients there was increased recruitment of frontal lobe regions for performance of short term tasks and the recruitment of frontal regions was associated with performance of the task [23][24].…”

Section: Introductionmentioning

confidence: 92%

Altered Brain Activation During a Verbal Working Memory Task in Subjects with Amnestic Mild Cognitive Impairment

Bokde

Karmann

Born

et al. 2010

JAD

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In subjects with Mild Cognitive Impairment (MCI) memory disorders indicate a high risk for conversion to Alzheimer's disease (AD). The objective of this study was to delineate the differences in brain activation between amnestic MCI and age-matched healthy controls (HC) during a verbal working memory task. The verbal working memory task was a delay match to sample design. Brain activation was measured using functional magnetic resonance imaging. There were 8 subjects in each group and were matched for performance. The task was analyzed as an event-related design. Group differences were calculated using Analysis of Covariance (ANCOVA) with statistical significance at p < 0.05 corrected. Both groups activated a wide network in the posterior and frontal areas of the brain. There was higher activation in the parietal and frontal lobes in the MCI compared to the HC during the maintenance phase. There were no areas in the HC that activated higher than the MCI subjects. Response time in the task in the HC group was correlated to the left hippocampus during encoding phase and to the parietal and frontal areas during the recall phase. In the MCI group there was strong correlation to the inferior and middle temporal gyrii during encoding, the middle frontal gyrus during the maintenance phase, and hippocampus during recall phase. The activation differences between groups may be compensatory mechanisms within the MCI group for the effects of the putative AD neuropathology. This has been the first study that has examined verbal working memory in MCI.

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Section: Introductionmentioning

confidence: 92%

Altered Brain Activation During a Verbal Working Memory Task in Subjects with Amnestic Mild Cognitive Impairment

Bokde

Karmann

Born

et al. 2010

JAD

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“…The complex interplay between dysfunctional and adaptational processes in the brain was shown in functional activation neuroimaging studies in older healthy subjects Grady 1996;Grady 2002;Grady et al 2002;Grady et al 2003;Damoiseaux et al 2008;Grady et al 2008), in subjects at high risk to develop AD (Dickerson et al 2005;Rombouts et al 2005;Bartres-Faz et al 2008;Bokde et al 2008;Bosch et al 2010) or with already manifest AD (Horwitz et al 1995;Pihlajamaki et al 2008;Rosenbaum et al 2008;Dickerson et al 2009;Rombouts et al 2009;. A large array of functional activation studies performed with a variety of multimodal activation paradigms revealed a high level of heterogeneity across experiments and study groups, making it very difficult to create generally valid interpretations of these imaging data.…”

Section: Network Architecture Of the Brainmentioning

confidence: 99%

Recent developments of functional magnetic resonance imaging research for drug development in Alzheimer's disease

Hampel

Prvulovic

Teipel

et al. 2011

Progress in Neurobiology

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“…In this study, the task was to decide if two faces presented simultaneously were identical, and the reference region for the functional connectivity was the right fusiform gyrus, a key region in the perception of faces. Of interest in this study was that the activation in this task was not altered between the MCI subjects and the healthy controls (Bokde et al, 2008),…”

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confidence: 91%

Assessing neuronal networks: Understanding Alzheimer's disease

Bokde

Ewers

Hampel

2009

Progress in Neurobiology

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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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Functional abnormalities of the visual processing system in subjects with mild cognitive impairment: An fMRI study

Cited by 54 publications

References 39 publications

Altered Brain Activation During a Verbal Working Memory Task in Subjects with Amnestic Mild Cognitive Impairment

Altered Brain Activation During a Verbal Working Memory Task in Subjects with Amnestic Mild Cognitive Impairment

Recent developments of functional magnetic resonance imaging research for drug development in Alzheimer's disease

Assessing neuronal networks: Understanding Alzheimer's disease

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