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Functional connectivity in dementia with Lewy bodies: What can the resting state show about visual hallucinations in this disease?

Lookup NU author(s): Dr Luis Peraza Rodriguez, Dr Michael Firbank, Professor John O'Brien, Professor John-Paul Taylor

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Abstract

Lewy body dementia (LBD) is a neurodegenerative disease associated with alpha-synuclein inclusions within theneuron's body known as Lewy bodies (LBs). LBD is an umbrella concept used to describe two different but veryrelated diseases; Parkinsons disease dementia and dementia with LBs (DLB). Both pathologies present withsimilar symptoms including fluctuating cognition, parkinsonism, and visual hallucinations (VHs). In DLB, VHs are particularly common and can be often be highly distressing to the patient although theiraetiology is poorly understood. On the basis of neuroimaging and neuropathology data there is evidence foralterations in the visual system which contribute to their occurrence although the spatial localization of thesechanges appears to vary from study to study. In our study, 16 patients diagnosed with DLB and 12 healthy controls (HC) had resting state fMRI acquired. Toinfer RSNs from both groups, concatenated Melodic implemented in FSL was run. 22 ICs were identified asRSNs such as the DMN (I and II), lateral/medial visual networks (VNs), and left/right dorsal visual streamnetworks (DVNs). These RSNs were chosen for a second processing step of dual regression (DR) whichperforms a spatial GLM between the RSN maps and the brain volume. Correction for age, sex and grey matteratrophies was then applied. DR identified two significant RSNs (corrected pvalue <0.05); the medial VN (Fig. 1a) and the left DVN (Fig. 1b) ,which showed a significant decrease of brain connectivity with the left medial temporal gyrus and visual cortexrespectively. In addition we found a significant correlation (pvalue<0.01) between the left medial temporal gyrusand severity of VHs. This concurs with prior evidences showing that LB related neuropathological change in thisarea is associated with VH. Our evidence of distributed network desynchrony between higher and lower visualareas provides empirical support for interactive models of VH which have suggested that a combination of poorperceptual bottom up and poor top-down binding leads to the intrusion of VH in the visual scene.


Publication metadata

Author(s): Peraza LR, Kaiser M, Firbank M, O'Brien J, Taylor J-P

Editor(s): British Neuroscience Association

Publication type: Conference Proceedings (inc. Abstract)

Publication status: Published

Conference Name: BNA Conference 2013

Year of Conference: 2013

Pages: P3-F-196

Date deposited: 11/04/2013

ISSN: 1345-8301

Publisher: BNA

URL: http://www.bna2013.com/


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