title: Link between hippocampus' raised local and eased global intrinsic connectivity in AD.
abstract: BACKGROUND
  The hippocampus (HP) is part of the default mode network (DMN), and both are key targets of Alzheimer's disease (AD). Because of widespread network degeneration, it has been suggested that increasing HP disconnection from the DMN may lead to progressive disinhibition of intra-HP synchronized activity.
  
  
  METHODS
  To analyze HP local (i.e., within HP) and global (i.e., within DMN) intrinsic functional connectivity (local/global intrinsic functional connectivity [iFC]), healthy controls and patients with mild cognitive impairment and AD dementia were assessed by spatial high and normal resolution resting-state functional magnetic resonance imaging.
  
  
  RESULTS
  Although patients' parietal local-iFC was reduced and positively correlated with reduced global-iFC within the DMN, HP local connectivity was progressively increased and negatively correlated with HP decreased global connectivity. Increased intra-HP connectivity was associated with impaired memory.
  
  
  CONCLUSIONS
  Our result demonstrates a link between increased local and reduced global hippocampal connectivity in AD. Increased intra-HP synchrony may contribute to distinct symptoms such as memory impairment or more speculatively epileptic seizure.
authors.affiliation: Department of Neuroradiology, Technische Universität München, Munich, Germany; TUM-Neuroimaging Center, Technische Universität München, Munich, Germany.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Pasquini
authors.affiliation: TUM-Neuroimaging Center, Technische Universität München, Munich, Germany; Department of Neurology, Christian Doppler Klinik, Paracelsus Medical University Salzburg, Salzburg, Austria.
authors.forename: Martin
authors.initials: M
authors.lastname: Scherr
authors.affiliation: Department of Neuroradiology, Technische Universität München, Munich, Germany; TUM-Neuroimaging Center, Technische Universität München, Munich, Germany; Department of Nuclear Medicine, Technische Universität München, Munich, Germany.
authors.forename: Masoud
authors.initials: M
authors.lastname: Tahmasian
authors.affiliation: Department of Neuroradiology, Technische Universität München, Munich, Germany.
authors.forename: Chun
authors.initials: C
authors.lastname: Meng
authors.affiliation: TUM-Neuroimaging Center, Technische Universität München, Munich, Germany; Department of Experimental Psychology, Oxford University, Oxford, United Kingdom.
authors.forename: Nicholas E
authors.initials: NE
authors.lastname: Myers
authors.affiliation: Department of Psychiatry, Technische Universität München, Munich, Germany.
authors.forename: Marion
authors.initials: M
authors.lastname: Ortner
authors.affiliation: TUM-Neuroimaging Center, Technische Universität München, Munich, Germany; Department of Neurology of Klinikum rechts der Isar, Technische Universität München, Munich, Germany.
authors.forename: Mark
authors.initials: M
authors.lastname: Mühlau
authors.affiliation: Department of Psychiatry, Technische Universität München, Munich, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Kurz
authors.affiliation: Department of Psychiatry, Technische Universität München, Munich, Germany.
authors.forename: Hans
authors.initials: H
authors.lastname: Förstl
authors.affiliation: Department of Neuroradiology, Technische Universität München, Munich, Germany.
authors.forename: Claus
authors.initials: C
authors.lastname: Zimmer
authors.affiliation: Department of Psychiatry, Technische Universität München, Munich, Germany.
authors.forename: Timo
authors.initials: T
authors.lastname: Grimmer
authors.affiliation: Department of Neuroradiology, Technische Universität München, Munich, Germany; TUM-Neuroimaging Center, Technische Universität München, Munich, Germany.
authors.forename: Afra M
authors.initials: AM
authors.lastname: Wohlschläger
authors.affiliation: Department of Neuroradiology, Technische Universität München, Munich, Germany; TUM-Neuroimaging Center, Technische Universität München, Munich, Germany; Department of Nuclear Medicine, Technische Universität München, Munich, Germany.
authors.forename: Valentin
authors.initials: V
authors.lastname: Riedl
authors.affiliation: Department of Neuroradiology, Technische Universität München, Munich, Germany; TUM-Neuroimaging Center, Technische Universität München, Munich, Germany; Department of Psychiatry, Technische Universität München, Munich, Germany. Electronic address: c.sorg@lrz.tum.de.
authors.forename: Christian
authors.initials: C
authors.lastname: Sorg
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000473:pathology*; D000704:Analysis of Variance; D005260:Female; D006624:Hippocampus / Q000098:blood supply / Q000473:pathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009415:Nerve Net / Q000098:blood supply / Q000473:pathology*; D009434:Neural Pathways / Q000098:blood supply / Q000473:pathology*; D009460:Neurologic Examination; D010100:Oxygen / Q000097:blood; D011569:Psychiatric Status Rating Scales
chemical_list: D010100:Oxygen
keywords: Alzheimer's disease; Default mode network; High-resolution resting-state fMRI; Hippocampus; Independent component analysis; Intrinsic functional connectivity; Mild cognitive impairment; Synchrony