title: APOE status modulates the changes in network connectivity induced by brain stimulation in non-demented elders.
abstract: Behavioral consequences of a brain insult represent an interaction between the injury and the capacity of the rest of the brain to adapt to it. We provide experimental support for the notion that genetic factors play a critical role in such adaptation. We induced a controlled brain disruption using repetitive transcranial magnetic stimulation (rTMS) and show that APOE status determines its impact on distributed brain networks as assessed by functional MRI (fMRI).Twenty non-demented elders exhibiting mild memory dysfunction underwent two fMRI studies during face-name encoding tasks (before and after rTMS). Baseline task performance was associated with activation of a network of brain regions in prefrontal, parietal, medial temporal and visual associative areas. APOE ε4 bearers exhibited this pattern in two separate independent components, whereas ε4-non carriers presented a single partially overlapping network. Following rTMS all subjects showed slight ameliorations in memory performance, regardless of APOE status. However, after rTMS APOE ε4-carriers showed significant changes in brain network activation, expressing strikingly similar spatial configuration as the one observed in the non-carrier group prior to stimulation. Similarly, activity in areas of the default-mode network (DMN) was found in a single component among the ε4-non bearers, whereas among carriers it appeared disaggregated in three distinct spatiotemporal components that changed to an integrated single component after rTMS.Our findings demonstrate that genetic background play a fundamental role in the brain responses to focal insults, conditioning expression of distinct brain networks to sustain similar cognitive performance.
authors.affiliation: Department de Psiquiatria i Psicobiologia Clinica, Universitat de Barcelona, Barcelona, Catalonia, Spain.
authors.forename: Cleofé
authors.initials: C
authors.lastname: Peña-Gomez
authors.forename: Cristina
authors.initials: C
authors.lastname: Solé-Padullés
authors.forename: Imma C
authors.initials: IC
authors.lastname: Clemente
authors.forename: Carme
authors.initials: C
authors.lastname: Junqué
authors.forename: Núria
authors.initials: N
authors.lastname: Bargalló
authors.forename: Beatriz
authors.initials: B
authors.lastname: Bosch
authors.forename: José Luis
authors.initials: JL
authors.lastname: Molinuevo
authors.forename: Josep
authors.initials: J
authors.lastname: Valls-Solé
authors.forename: Alvaro
authors.initials: A
authors.lastname: Pascual-Leone
authors.forename: David
authors.initials: D
authors.lastname: Bartrés-Faz
mesh_terms: D000368:Aged; D001057:Apolipoproteins E / Q000378:metabolism*; D001931:Brain Mapping; D046690:Deep Brain Stimulation; D005145:Face; D005260:Female; D006624:Hippocampus / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008569:Memory Disorders / Q000378:metabolism / Q000473:pathology*; D009275:Names; D009415:Nerve Net / Q000502:physiology*; D009483:Neuropsychological Tests; D013028:Space Perception / Q000502:physiology
chemical_list: D001057:Apolipoproteins E