title: Additional resources and the default mode network: Evidence of increased connectivity and decreased white matter integrity in amyotrophic lateral sclerosis.
abstract: In amyotrophic lateral sclerosis (ALS), cognition is affected. Cortical atrophy in frontal and temporal areas has been associated with the cognitive profile of patients. Additionally, reduced metabolic turnover and regional cerebral blood flow in frontal areas indicative of reduced neural activity have been reported for ALS. We hypothesize that functional connectivity in non-task associated functional default mode network (DMN) is associated with cognitive profile and white matter integrity. This study focused on specific cognitive tasks known to be impaired in ALS such as verbal fluency and attention, and the relationship with functional connectivity in the DMN and white matter integrity. Nine patients and 11 controls were measured with an extensive neuropsychological battery. Resting-state functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) data were acquired. Results showed that ALS patients performed significantly worse in attention and verbal fluency task. Patients showed increased functional connectivity in parahippocampal and parietal areas of the non-task associated DMN compared to controls. The more pronounced the cognitive deficits, the stronger the increase in functional connectivity in those areas. White matter integrity was reduced in frontal areas in the patients. In conclusion, increased connectivity in the DMN in parahippocampal and parietal areas might represent recruitment of accessory brain regions to compensate for dysfunctional frontal networks.
authors.affiliation: Department of Neurology, University of Ulm , Ulm , Germany.
authors.forename: Johanna
authors.initials: J
authors.lastname: Heimrath
authors.forename: Martin
authors.initials: M
authors.lastname: Gorges
authors.forename: Jan
authors.initials: J
authors.lastname: Kassubek
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Müller
authors.forename: Niels
authors.initials: N
authors.lastname: Birbaumer
authors.forename: Albert C
authors.initials: AC
authors.lastname: Ludolph
authors.forename: Dorothée
authors.initials: D
authors.lastname: Lulé
mesh_terms: D000328:Adult; D000368:Aged; D000690:Amyotrophic Lateral Sclerosis / Q000150:complications*; D001284:Atrophy; D001931:Brain Mapping; D016022:Case-Control Studies; D003072:Cognition Disorders / Q000175:diagnosis / Q000209:etiology; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D056784:Leukoencephalopathies / Q000209:etiology* / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009434:Neural Pathways / Q000098:blood supply / Q000473:pathology*; D009483:Neuropsychological Tests; D010100:Oxygen / Q000097:blood; D012146:Rest; D018709:Statistics, Nonparametric; D066127:White Matter / Q000098:blood supply / Q000473:pathology*
chemical_list: D010100:Oxygen
keywords: Default mode network; amyotrophic lateral sclerosis (ALS); cognition; cortical plasticity; fMRI