title: Alzheimer's patients engage an alternative network during a memory task.
abstract: We conducted an event-related functional magnetic resonance imaging experiment to better understand the potentially compensatory alternative brain networks activated by a clinically relevant face-name association task in Alzheimer's disease (AD) patients and matched control subjects. We recruited 17 healthy subjects and 12 AD patients at an early stage of the disease. They underwent functional magnetic resonance imaging scanning in four sessions. Each of the sessions combined a "study" phase and a "test" phase. Face/name pairs were presented in each study phase, and subjects were asked to associate faces with names. In the test phase, a recognition task, faces seen in the study phase were presented each with four different names. The task required selection of appropriate previously associated names from the study phase. Responses were recorded for post hoc classification into those successfully or unsuccessfully encoded. There were significant differences between the groups in accuracy and reaction time. Comparison of correctly versus incorrectly encoded and recognized pairs in the two groups indicated bilateral hippocampal hypoactivation both when encoding and recognizing in the AD group. Moreover, patients showed bilateral hyperactivation of parts of the parietal and frontal lobes. We discuss whether hyperactivation of a frontoparietal network reflects compensatory strategies for failing associative memory in AD patients.
authors.affiliation: Wellcome Department of Imaging Neuroscience, London, United Kingdom. jeremie.parente@toulouse.inserm.fr
authors.forename: Jérémie
authors.initials: J
authors.lastname: Pariente
authors.forename: Susanna
authors.initials: S
authors.lastname: Cole
authors.forename: Richard
authors.initials: R
authors.lastname: Henson
authors.forename: Linda
authors.initials: L
authors.lastname: Clare
authors.forename: Angus
authors.initials: A
authors.lastname: Kennedy
authors.forename: Martin
authors.initials: M
authors.lastname: Rossor
authors.forename: Lisa
authors.initials: L
authors.lastname: Cipoloti
authors.forename: Michèle
authors.initials: M
authors.lastname: Puel
authors.forename: Jean Francois
authors.initials: JF
authors.lastname: Demonet
authors.forename: Francois
authors.initials: F
authors.lastname: Chollet
authors.forename: Richard S J
authors.initials: RS
authors.lastname: Frackowiak
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000503:physiopathology*; D001245:Association Learning / Q000502:physiology; D005260:Female; D006624:Hippocampus / Q000166:cytology / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009434:Neural Pathways / Q000502:physiology; D010296:Parietal Lobe / Q000166:cytology / Q000502:physiology; D010364:Pattern Recognition, Visual / Q000502:physiology*; D017397:Prefrontal Cortex / Q000166:cytology / Q000502:physiology; D021641:Recognition, Psychology / Q000502:physiology*