title: Disruption of caudate working memory activation in chronic blast-related traumatic brain injury.
abstract: Mild to moderate traumatic brain injury (TBI) due to blast exposure is frequently diagnosed in veterans returning from the wars in Iraq and Afghanistan. However, it is unclear whether neural damage resulting from blast TBI differs from that found in TBI due to blunt-force trauma (e.g., falls and motor vehicle crashes). Little is also known about the effects of blast TBI on neural networks, particularly over the long term. Because impairment in working memory has been linked to blunt-force TBI, the present functional magnetic resonance imaging (fMRI) study sought to investigate whether brain activation in response to a working memory task would discriminate blunt-force from blast TBI. Twenty-five veterans (mean age = 29.8 years, standard deviation = 6.01 years, 1 female) who incurred TBI due to blast an average of 4.2 years prior to enrollment and 25 civilians (mean age = 27.4 years, standard deviation = 6.68 years, 4 females) with TBI due to blunt-force trauma performed the Sternberg Item Recognition Task while undergoing fMRI. The task involved encoding 1, 3, or 5 items in working memory. A group of 25 veterans (mean age = 29.9 years, standard deviation = 5.53 years, 0 females) and a group of 25 civilians (mean age = 27.3 years, standard deviation = 5.81 years, 0 females) without history of TBI underwent identical imaging procedures and served as controls. Results indicated that the civilian TBI group and both control groups demonstrated a monotonic relationship between working memory set size and activation in the right caudate during encoding, whereas the blast TBI group did not (p < 0.05, corrected for multiple comparisons using False Discovery Rate). Blast TBI was also associated with worse performance on the Sternberg Item Recognition Task relative to the other groups, although no other group differences were found on neuropsychological measures of episodic memory, inhibition, and general processing speed. These results could not be attributed to caudate atrophy or the presence of PTSD symptoms. Our results point to a specific vulnerability of the caudate to blast injury. Changes in activation during the Sternberg Item Recognition Task, and potentially other tasks that recruit the caudate, may serve as biomarkers for blast TBI.
authors.affiliation: Research Service Line, Michael E. DeBakey Veterans Affairs Medical Center, Houston, TX, USA ; Department of Physical Medicine and Rehabilitation, Baylor College of Medicine, Houston, TX, USA.
authors.forename: Mary R
authors.initials: MR
authors.lastname: Newsome
authors.affiliation: Department of Neurology, Medical College of Wisconsin, Milwaukee, WI, USA.
authors.forename: Sally
authors.initials: S
authors.lastname: Durgerian
authors.affiliation: Schey Center for Cognitive Neuroimaging, Neurological Institute, Cleveland Clinic, Cleveland, OH, USA.
authors.forename: Lyla
authors.initials: L
authors.lastname: Mourany
authors.affiliation: Research Service Line, Michael E. DeBakey Veterans Affairs Medical Center, Houston, TX, USA ; Department of Physical Medicine and Rehabilitation, Baylor College of Medicine, Houston, TX, USA.
authors.forename: Randall S
authors.initials: RS
authors.lastname: Scheibel
authors.affiliation: Imaging Institute, Cleveland Clinic, Cleveland, OH, USA.
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Lowe
authors.affiliation: Imaging Institute, Cleveland Clinic, Cleveland, OH, USA.
authors.forename: Erik B
authors.initials: EB
authors.lastname: Beall
authors.affiliation: Imaging Institute, Cleveland Clinic, Cleveland, OH, USA.
authors.forename: Katherine A
authors.initials: KA
authors.lastname: Koenig
authors.affiliation: Schey Center for Cognitive Neuroimaging, Neurological Institute, Cleveland Clinic, Cleveland, OH, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Parsons
authors.affiliation: Research Service Line, Michael E. DeBakey Veterans Affairs Medical Center, Houston, TX, USA ; Department of Physical Medicine and Rehabilitation, Baylor College of Medicine, Houston, TX, USA.
authors.forename: Maya
authors.initials: M
authors.lastname: Troyanskaya
authors.affiliation: Schey Center for Cognitive Neuroimaging, Neurological Institute, Cleveland Clinic, Cleveland, OH, USA.
authors.forename: Christine
authors.initials: C
authors.lastname: Reece
authors.affiliation: Research Service Line, Michael E. DeBakey Veterans Affairs Medical Center, Houston, TX, USA ; Department of Physical Medicine and Rehabilitation, Baylor College of Medicine, Houston, TX, USA.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Wilde
authors.affiliation: Geriatric Research Education and Clinical Center (GRECC), Wm. S. Middleton Memorial Veterans Affairs Hospital, Madison, WI, USA.
authors.forename: Barbara L
authors.initials: BL
authors.lastname: Fischer
authors.affiliation: Imaging Institute, Cleveland Clinic, Cleveland, OH, USA.
authors.forename: Stephen E
authors.initials: SE
authors.lastname: Jones
authors.affiliation: Diagnostic and Therapeutic Care, Michael E. DeBakey Veterans Affairs Medical Center, Houston, TX, USA ; Department of Radiology, Baylor College of Medicine, Houston, TX, USA.
authors.forename: Rajan
authors.initials: R
authors.lastname: Agarwal
authors.affiliation: Research Service Line, Michael E. DeBakey Veterans Affairs Medical Center, Houston, TX, USA ; Department of Physical Medicine and Rehabilitation, Baylor College of Medicine, Houston, TX, USA.
authors.forename: Harvey S
authors.initials: HS
authors.lastname: Levin
authors.affiliation: Schey Center for Cognitive Neuroimaging, Neurological Institute, Cleveland Clinic, Cleveland, OH, USA.
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Rao
mesh_terms: D000328:Adult; D055826:Afghan Campaign 2001-; D001753:Blast Injuries / Q000150:complications / Q000503:physiopathology*; D020208:Brain Injury, Chronic / Q000150:complications / Q000503:physiopathology*; D002421:Caudate Nucleus / Q000503:physiopathology*; D005260:Female; D006801:Humans; D054542:Iraq War, 2003-2011; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008569:Memory Disorders / Q000209:etiology / Q000503:physiopathology*; D008570:Memory, Short-Term / Q000502:physiology*; D014728:Veterans; D055815:Young Adult
keywords: Concussion; Cortical plasticity; Traumatic brain injury; Veteran; Working memory; fMRI