Disruption of Semantic Network in Mild Alzheimer's Disease Revealed by Resting-State fMRI. (10th February 2018)

• Record Type: Journal Article
• Authors: Mascali, Daniele; DiNuzzo, Mauro; Serra, Laura; Mangia, Silvia; Maraviglia, Bruno; Bozzali, Marco; Giove, Federico
• Is Part Of: Neuroscience. Volume 371(2018)
• Page Start: 38
• Page End: 48
• Publication Date: 2018-02-10
• Subjects: AD Alzheimer's disease -- BOLD blood-oxygen-level-dependent -- CSF Cerebral Spinal Fluid -- EPI echo planar imaging -- FC functional connectivity -- FD framewise displacement -- fMRI functional magnetic resonance imaging -- FWHM full width at half maximum -- GLM general linear model -- GM gray matter -- GMV gray matter volume -- HC healthy controls -- MMSE mean mini-mental state examination -- MNI Montreal Neurological Institute -- pMTG posterior middle temporal gyrus -- POp pars opercularis -- TMS transcranial magnetic stimulation -- wGBC weighted Global Brain Connectivity -- WM White Matter -- wRBC weighted Regional Brain Connectivity; Alzheimer's disease -- semantic control network -- posterior middle temporal gyrus -- inferior frontal gyrus -- resting-state fMRI -- voxel-wise functional connectivity; Neurochemistry -- Periodicals; Neurophysiology -- Periodicals; Neurology -- Periodicals; Neurochimie -- Périodiques; Neurophysiologie -- Périodiques; Neurochemistry; Neurophysiology; Electronic journals; Periodicals; Electronic journals; 612.8
• DOI: 10.1016/j.neuroscience.2017.11.030
• Languages: English
• ISSNs: 0306-4522

Abstract

Highlights: Mild AD patients showed reduced connectivity within the semantic control network compared to healthy control subjects. Reduced connectivity was found in the left pars opercularis and in the left posterior middle temporal gyrus. The two identified regions showed also reduced connectivity to other regions involved in language-semantic processing. Abstract: Subtle semantic deficits can be observed in Alzheimer's disease (AD) patients even in the early stages of the illness. In this work, we tested the hypothesis that the semantic control network is deregulated in mild AD patients. We assessed the integrity of the semantic control system using resting-state functional magnetic resonance imaging in a cohort of patients with mild AD ( n = 38; mean mini-mental state examination = 20.5) and in a group of age-matched healthy controls ( n = 19). Voxel-wise analysis spatially constrained in the left fronto-temporal semantic control network identified two regions with altered functional connectivity (FC) in AD patients, specifically in the pars opercularis (POp, BA44) and in the posterior middle temporal gyrus (pMTG, BA21). Using whole-brain seed-based analysis, we demonstrated that these two regions have altered FC even beyond the semantic control network. In particular, the pMTG displayed a wide-distributed pattern of lower connectivity to several brain regions involved in language-semantic processing, along with a possibly compensatory higher connectivity to the Wernicke's area. We conclude that in mild AD brain regions belonging to the semantic control network are abnormally connected not only within the network, but also to other areas known to be critical for language processing.