title: A longitudinal fMRI study of working memory in severe TBI patients with diffuse axonal injury.
abstract: Traumatic brain injury (TBI) patients have working memory deficits and altered patterns of brain activation during this function. The evolution of the impairment has not been examined to date. This study investigated longitudinal changes in brain activation during a working memory task. Twelve patients with severe and diffuse TBI and ten healthy matched controls were fMRI scanned twice at a 6-month interval during an n-back task (0-, 2- and 3-back). All the TBI patients selected presented signs of diffuse axonal injury on CT but had no evidence of focal lesions on MRI clinical examination. Significant changes in brain activation over time were observed in patients, but not in controls. During the first examination, though both groups engaged bilateral fronto-parietal regions known to be involved in working memory, activation of the right superior frontal gyrus was low in the TBI group. However, the difference between TBI and controls had decreased significantly after 6 months. A factor analysis confirmed the greater increase in activation in the right superior frontal cortex in the TBI group than in healthy controls, leading to normalization of the brain activation pattern. In conclusion, this longitudinal study provides evidence of a progressive normalization of the working memory activation pattern after diffuse axonal injury in severe TBI, coinciding with an improvement in performance on this function.
authors.affiliation: Department of Neuropsychology, Institut Universitari de Neurorehabilitació Guttmann, Badalona, Spain.
authors.forename: Rocio
authors.initials: R
authors.lastname: Sanchez-Carrion
authors.forename: Davinia
authors.initials: D
authors.lastname: Fernandez-Espejo
authors.forename: Carme
authors.initials: C
authors.lastname: Junque
authors.forename: Carles
authors.initials: C
authors.lastname: Falcon
authors.forename: Nuria
authors.initials: N
authors.lastname: Bargallo
authors.forename: Teresa
authors.initials: T
authors.lastname: Roig
authors.forename: Montserrat
authors.initials: M
authors.lastname: Bernabeu
authors.forename: José M
authors.initials: JM
authors.lastname: Tormos
authors.forename: Pere
authors.initials: P
authors.lastname: Vendrell
mesh_terms: D000328:Adult; D001930:Brain Injuries / Q000150:complications / Q000503:physiopathology; D001931:Brain Mapping; D020833:Diffuse Axonal Injury / Q000150:complications / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D008297:Male; D008569:Memory Disorders / Q000209:etiology / Q000503:physiopathology*; D008570:Memory, Short-Term / Q000502:physiology; D009483:Neuropsychological Tests