51
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Braun M, Vaibhav K, Saad N, Fatima S, Brann DW, Vender JR, Wang LP, Hoda MN, Baban B, Dhandapani KM. Activation of Myeloid TLR4 Mediates T Lymphocyte Polarization after Traumatic Brain Injury. THE JOURNAL OF IMMUNOLOGY 2017; 198:3615-3626. [PMID: 28341672 DOI: 10.4049/jimmunol.1601948] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Accepted: 02/21/2017] [Indexed: 12/15/2022]
Abstract
Traumatic brain injury (TBI) is a major public health issue, producing significant patient mortality and poor long-term outcomes. Increasing evidence suggests an important, yet poorly defined, role for the immune system in the development of secondary neurologic injury over the days and weeks following a TBI. In this study, we tested the hypothesis that peripheral macrophage infiltration initiates long-lasting adaptive immune responses after TBI. Using a murine controlled cortical impact model, we used adoptive transfer, transgenic, and bone marrow chimera approaches to show increased infiltration and proinflammatory (classically activated [M1]) polarization of macrophages for up to 3 wk post-TBI. Monocytes purified from the injured brain stimulated the proliferation of naive T lymphocytes, enhanced the polarization of T effector cells (TH1/TH17), and decreased the production of regulatory T cells in an MLR. Similarly, elevated T effector cell polarization within blood and brain tissue was attenuated by myeloid cell depletion after TBI. Functionally, C3H/HeJ (TLR4 mutant) mice reversed M1 macrophage and TH1/TH17 polarization after TBI compared with C3H/OuJ (wild-type) mice. Moreover, brain monocytes isolated from C3H/HeJ mice were less potent stimulators of T lymphocyte proliferation and TH1/TH17 polarization compared with C3H/OuJ monocytes. Taken together, our data implicate TLR4-dependent, M1 macrophage trafficking/polarization into the CNS as a key mechanistic link between acute TBI and long-term, adaptive immune responses.
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Affiliation(s)
- Molly Braun
- Department of Neurosurgery, Medical College of Georgia, Augusta University, Augusta, GA 30912
| | - Kumar Vaibhav
- Department of Neurosurgery, Medical College of Georgia, Augusta University, Augusta, GA 30912.,Department of Medical Laboratory, Imaging, and Radiological Sciences, College of Allied Health Sciences, Augusta University, Augusta, GA 30912
| | - Nancy Saad
- Department of Oral Biology, Dental College of Georgia, Augusta University, Augusta, GA 30912
| | - Sumbul Fatima
- Department of Medical Laboratory, Imaging, and Radiological Sciences, College of Allied Health Sciences, Augusta University, Augusta, GA 30912.,Department of Neurology, Medical College of Georgia, Augusta University, Augusta, GA 30912
| | - Darrell W Brann
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, Augusta, GA 30912.,Charlie Norwood VA Medical Center, Augusta, GA 30912
| | - John R Vender
- Department of Neurosurgery, Medical College of Georgia, Augusta University, Augusta, GA 30912
| | - Lei P Wang
- Department of Psychiatry, Medical College of Georgia, Augusta University, Augusta, GA 30912; and
| | - Md Nasrul Hoda
- Department of Medical Laboratory, Imaging, and Radiological Sciences, College of Allied Health Sciences, Augusta University, Augusta, GA 30912.,Department of Neurology, Medical College of Georgia, Augusta University, Augusta, GA 30912.,Charlie Norwood VA Medical Center, Augusta, GA 30912
| | - Babak Baban
- Department of Oral Biology, Dental College of Georgia, Augusta University, Augusta, GA 30912.,Department of Neurology, Medical College of Georgia, Augusta University, Augusta, GA 30912.,Department of Surgery, Medical College of Georgia, Augusta University, Augusta, GA 30912
| | - Krishnan M Dhandapani
- Department of Neurosurgery, Medical College of Georgia, Augusta University, Augusta, GA 30912; .,Charlie Norwood VA Medical Center, Augusta, GA 30912
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52
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Wogensen E, Gram MG, Sommer JB, Vilsen CR, Mogensen J, Malá H. Delayed voluntary exercise does not enhance cognitive performance after hippocampal injury: an investigation of differentially distributed exercise protocols. J Exerc Rehabil 2016; 12:401-412. [PMID: 27807517 PMCID: PMC5091054 DOI: 10.12965/jer.1632680.340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Accepted: 09/05/2016] [Indexed: 11/22/2022] Open
Abstract
Voluntary exercise has previously been shown to enhance cognitive recovery after acquired brain injury (ABI). The present study evaluated effects of two differentially distributed protocols of delayed, voluntary exercise on cognitive recovery using an allocentric place learning task in an 8-arm radial maze. Fifty-four Wistar rats were subjected to either bilateral transection of the fimbria-fornix (FF) or to sham surgery. Twenty-one days postinjury, the animals started exercising in running wheels either for 14 consecutive days (FF/exercise daily [ExD], sham/ExD) or every other day for 14 days (FF/exercise every second day [ExS], sham/ExS). Additional groups were given no exercise treatment (FF/not exercise [NE], sham/NE). Regardless of how exercise was distributed, we found no cognitively enhancing effects of exercise in the brain injured animals. Design and protocol factors possibly affecting the efficacy of post-ABI exercise are discussed.
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Affiliation(s)
- Elise Wogensen
- The Unit for Cognitive Neuroscience, Department of Psychology, University of Copenhagen, Copenhagen,
Denmark
| | - Marie Gajhede Gram
- The Unit for Cognitive Neuroscience, Department of Psychology, University of Copenhagen, Copenhagen,
Denmark
| | - Jens Bak Sommer
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen,
Denmark
| | - Christina Rytter Vilsen
- The Unit for Cognitive Neuroscience, Department of Psychology, University of Copenhagen, Copenhagen,
Denmark
| | - Jesper Mogensen
- The Unit for Cognitive Neuroscience, Department of Psychology, University of Copenhagen, Copenhagen,
Denmark
| | - Hana Malá
- The Unit for Cognitive Neuroscience, Department of Psychology, University of Copenhagen, Copenhagen,
Denmark
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53
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Tate DF, Wade BSC, Velez CS, Drennon AM, Bolzenius J, Gutman BA, Thompson PM, Lewis JD, Wilde EA, Bigler ED, Shenton ME, Ritter JL, York GE. Volumetric and shape analyses of subcortical structures in United States service members with mild traumatic brain injury. J Neurol 2016; 263:2065-79. [PMID: 27435967 PMCID: PMC5564450 DOI: 10.1007/s00415-016-8236-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Revised: 07/07/2016] [Accepted: 07/08/2016] [Indexed: 10/21/2022]
Abstract
Mild traumatic brain injury (mTBI) is a significant health concern. The majority who sustain mTBI recover, although ~20 % continue to experience symptoms that can interfere with quality of life. Accordingly, there is a critical need to improve diagnosis, prognostic accuracy, and monitoring (recovery trajectory over time) of mTBI. Volumetric magnetic resonance imaging (MRI) has been successfully utilized to examine TBI. One promising improvement over standard volumetric approaches is to analyze high-dimensional shape characteristics of brain structures. In this study, subcortical shape and volume in 76 Service Members with mTBI was compared to 59 Service Members with orthopedic injury (OI) and 17 with post-traumatic stress disorder (PTSD) only. FreeSurfer was used to quantify structures from T1-weighted 3 T MRI data. Radial distance (RD) and Jacobian determinant (JD) were defined vertex-wise on parametric mesh-representations of subcortical structures. Linear regression was used to model associations between morphometry (volume and shape), TBI status, and time since injury (TSI) correcting for age, sex, intracranial volume, and level of education. Volumetric data was not significantly different between the groups. JD was significantly increased in the accumbens and caudate and significantly reduced in the thalamus of mTBI participants. Additional significant associations were noted between RD of the amygdala and TSI. Positive trend-level associations between TSI and the amygdala and accumbens were observed, while a negative association was observed for third ventricle. Our findings may aid in the initial diagnosis of mTBI, provide biological targets for functional examination, and elucidate regions that may continue remodeling after injury.
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Affiliation(s)
- David F Tate
- Missouri Institute of Mental Health, University of Missouri, St. Louis, 4633 World Parkway Circle, Berkeley, MO, 63134-3115, USA.
- Department of Physical Medicine and Rehabilitation, Baylor College of Medicine, Houston, TX, USA.
| | - Benjamin S C Wade
- Imaging Genetics Center, University of Southern California, Marina del Rey, CA, USA
| | - Carmen S Velez
- Missouri Institute of Mental Health, University of Missouri, St. Louis, 4633 World Parkway Circle, Berkeley, MO, 63134-3115, USA
| | - Ann Marie Drennon
- Defense and Veterans Brain Injury Centers, San Antonio Military Medical Center, San Antonio, TX, USA
| | - Jacob Bolzenius
- Missouri Institute of Mental Health, University of Missouri, St. Louis, 4633 World Parkway Circle, Berkeley, MO, 63134-3115, USA
| | - Boris A Gutman
- Imaging Genetics Center, University of Southern California, Marina del Rey, CA, USA
| | - Paul M Thompson
- Imaging Genetics Center, University of Southern California, Marina del Rey, CA, USA
| | - Jeffrey D Lewis
- Department of Neurology, Uniformed Services University of the Health Sciences School of Medicine, Bethesda, MD, USA
| | - Elisabeth A Wilde
- Department of Physical Medicine and Rehabilitation, Baylor College of Medicine, Houston, TX, USA
- Michael E. DeBakey VA Medical Center, Houston, TX, USA
| | - Erin D Bigler
- Departments of Psychology and Neuroscience, Brigham Young University, Provo, UT, USA
| | - Martha E Shenton
- Psychiatry Neuroimaging Laboratory, Department of Psychiatry and Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
- Brockton Division, VA Boston Healthcare System, Brockton, MA, USA
| | - John L Ritter
- Department of Radiology, Brooke Army Medical Center, San Antonio, TX, USA
| | - Gerald E York
- Alaska Radiology Associates, TBI Imaging and Research, Anchorage, AK, USA
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54
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Sharma B, Tomaszczyk JC, Dawson D, Turner GR, Colella B, Green REA. Feasibility of online self-administered cognitive training in moderate-severe brain injury. Disabil Rehabil 2016; 39:1380-1390. [PMID: 27414703 DOI: 10.1080/09638288.2016.1195453] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
PURPOSE Cognitive environmental enrichment (C-EE) offers promise for offsetting neural decline that is observed in chronic moderate-severe traumatic brain injury (TBI). Brain games are a delivery modality for C-EE that can be self-administered over the Internet without therapist oversight. To date, only one study has examined the feasibility of self-administered brain games in TBI, and the study focused predominantly on mild TBI. Therefore, the primary purpose of the current study was to examine the feasibility of self-administered brain games in moderate-severe TBI. A secondary and related purpose was to examine the feasibility of remote monitoring of any C-EE-induced adverse symptoms with a self-administered evaluation tool. METHOD Ten patients with moderate-severe TBI were asked to complete 12 weeks (60 min/day, five days/week) of online brain games with bi-weekly self-evaluation, intended to measure any adverse consequences of cognitive training (e.g., fatigue, eye strain). RESULTS There was modest weekly adherence (42.6% ± 4.4%, averaged across patients and weeks) and 70% patient retention; of the seven retained patients, six completed the self-evaluation questionnaire at least once/week for each week of the study. CONCLUSIONS Even patients with moderate-severe TBI can complete a demanding, online C-EE intervention and a self-administered symptom evaluation tool with limited therapist oversight, though at daily rate closer to 30 than 60 min per day. Further self-administered C-EE research is underway in our lab, with more extensive environmental support. Implications for Rehabilitation Online brain games (which may serve as a rehabilitation paradigm that can help offset the neurodegeneration observed in chronic TBI) can be feasibly self-administered by moderate-to-severe TBI patients. Brain games are a promising therapy modality, as they can be accessed by all moderate-to-severe TBI patients irrespective of geographic location, clinic and/or therapist availability, or impairments that limit mobility and access to rehabilitation services. Future efficacy trials that examine the effect of brain games for offsetting neurodegeneration in moderate-to-severe TBI patients are warranted.
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Affiliation(s)
- Bhanu Sharma
- a Rehabilitation Sciences Institute (Formerly Graduate Department of Rehabilitation Science) , University of Toronto , Toronto , Ontario , Canada.,b Toronto Rehabilitation Institute , University Health Network , Toronto , Ontario , Canada
| | - Jennifer C Tomaszczyk
- b Toronto Rehabilitation Institute , University Health Network , Toronto , Ontario , Canada
| | - Deirdre Dawson
- a Rehabilitation Sciences Institute (Formerly Graduate Department of Rehabilitation Science) , University of Toronto , Toronto , Ontario , Canada.,b Toronto Rehabilitation Institute , University Health Network , Toronto , Ontario , Canada.,c Rotman Research Institute, Baycrest , Toronto , Ontario , Canada.,d Department of Occupational Science & Occupational Therapy , University of Toronto , Toronto , Ontario , Canada
| | - Gary R Turner
- e Department of Psychology , York University , Toronto , Ontario , Canada
| | - Brenda Colella
- b Toronto Rehabilitation Institute , University Health Network , Toronto , Ontario , Canada
| | - Robin E A Green
- a Rehabilitation Sciences Institute (Formerly Graduate Department of Rehabilitation Science) , University of Toronto , Toronto , Ontario , Canada.,b Toronto Rehabilitation Institute , University Health Network , Toronto , Ontario , Canada
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55
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Konstantinou N, Pettemeridou E, Seimenis I, Eracleous E, Papacostas SS, Papanicolaou AC, Constantinidou F. Assessing the Relationship between Neurocognitive Performance and Brain Volume in Chronic Moderate-Severe Traumatic Brain Injury. Front Neurol 2016; 7:29. [PMID: 27014183 PMCID: PMC4785138 DOI: 10.3389/fneur.2016.00029] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Accepted: 02/24/2016] [Indexed: 11/13/2022] Open
Abstract
Objectives Characterize the scale and pattern of long-term atrophy in gray matter (GM), white matter (WM), and cerebrospinal fluid (CSF) in chronic moderate–severe traumatic brain injury (TBI) and its relationship to neurocognitive outcomes. Participants The TBI group consisted of 17 males with primary diagnosis of moderate–severe closed head injury. Participants had not received any systematic, post-acute rehabilitation and were recruited on average 8.36 years post-injury. The control group consisted of 15 males matched on age and education. Main measures Neurocognitive battery included widely used tests of verbal memory, visual memory, executive functioning, and attention/organization. GM, WM, and CSF volumes were calculated from segmented T1-weighted anatomical MR images. Voxel-based morphometry was employed to identify brain regions with differences in GM and WM between TBI and control groups. Results Chronic TBI results in significant neurocognitive impairments, and significant loss of GM and WM volume, and significant increase in CSF volume. Brain atrophy is not widespread, but it is rather distributed in a fronto-thalamic network. The extent of volume loss is predictive of performance on the neurocognitive tests. Conclusion Significant brain atrophy and associated neurocognitive impairments during the chronic stages of TBI support the notion that TBI results in a chronic condition with lifelong implications.
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Affiliation(s)
- Nikos Konstantinou
- Center for Applied Neuroscience, University of Cyprus, Nicosia, Cyprus; Department of Psychology, University of Cyprus, Nicosia, Cyprus
| | - Eva Pettemeridou
- Center for Applied Neuroscience, University of Cyprus, Nicosia, Cyprus; Department of Psychology, University of Cyprus, Nicosia, Cyprus
| | - Ioannis Seimenis
- Department of Medical Physics, Medical School, Democritus University of Thrace , Alexandroupolis , Greece
| | - Eleni Eracleous
- Medical Diagnostic Center "Ayios Therissos" , Nicosia , Cyprus
| | - Savvas S Papacostas
- Neurology Clinic B, The Cyprus Institute of Neurology and Genetics, The Cyprus School of Molecular Medicine , Nicosia , Cyprus
| | - Andrew C Papanicolaou
- Division of Clinical Neurosciences, Department of Pediatrics, The Le Bonheur Neuroscience Institute, University of Tennessee Health Science Center, Memphis, TN, USA; Division of Clinical Neurosciences, Department of Neurobiology and Anatomy, The Le Bonheur Neuroscience Institute, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Fofi Constantinidou
- Center for Applied Neuroscience, University of Cyprus, Nicosia, Cyprus; Department of Psychology, University of Cyprus, Nicosia, Cyprus
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56
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Hensley K, Poteshkina A, Johnson MF, Eslami P, Gabbita SP, Hristov AM, Venkova-Hristova KM, Harris-White ME. Autophagy Modulation by Lanthionine Ketimine Ethyl Ester Improves Long-Term Outcome after Central Fluid Percussion Injury in the Mouse. J Neurotrauma 2016; 33:1501-13. [PMID: 26530250 DOI: 10.1089/neu.2015.4196] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Diffuse axonal injury is recognized as a progressive and long-term consequence of traumatic brain injury. Axonal injury can have sustained negative consequences on neuronal functions such as anterograde and retrograde transport and cellular processes such as autophagy that depend on cytoarchitecture and axon integrity. These changes can lead to somatic atrophy and an inability to repair and promote plasticity. Obstruction of the autophagic process has been noted after brain injury, and rapamycin, a drug used to stimulate autophagy, has demonstrated positive effects in brain injury models. The optimization of drugs to promote beneficial autophagy without negative side effects could be used to attenuate traumatic brain injury and promote improved outcome. Lanthionine ketimine ethyl ester, a bioavailable derivative of a natural sulfur amino acid metabolite, has demonstrated effects on autophagy both in vitro and in vivo. Thirty minutes after a moderate central fluid percussion injury and throughout the survival period, lanthionine ketimine ethyl ester was administered, and mice were subsequently evaluated for learning and memory impairments and biochemical and histological changes over a 5-week period. Lanthionine ketimine ethyl ester, which we have shown previously to modulate autophagy markers and alleviate pathology and slow cognitive decline in the 3 × TgAD mouse model, spared cognition and pathology after central fluid percussion injury through a mechanism involving autophagy modulation.
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Affiliation(s)
- Kenneth Hensley
- 1 Department of Pathology, University of Toledo Health Science Campus , Toledo, Ohio.,2 Department of Neurosciences, University of Toledo Health Science Campus , Toledo, Ohio
| | - Aleksandra Poteshkina
- 4 Veterans Administration-Greater Los Angeles Healthcare System , Los Angeles, California
| | - Ming F Johnson
- 4 Veterans Administration-Greater Los Angeles Healthcare System , Los Angeles, California
| | - Pirooz Eslami
- 4 Veterans Administration-Greater Los Angeles Healthcare System , Los Angeles, California
| | | | - Alexandar M Hristov
- 1 Department of Pathology, University of Toledo Health Science Campus , Toledo, Ohio
| | | | - Marni E Harris-White
- 4 Veterans Administration-Greater Los Angeles Healthcare System , Los Angeles, California.,5 Department of Medicine, David Geffen School of Medicine at UCLA , Los Angeles, California
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57
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How TV, Hwang AS, Green REA, Mihailidis A. Envisioning future cognitive telerehabilitation technologies: a co-design process with clinicians. Disabil Rehabil Assist Technol 2016; 12:244-261. [DOI: 10.3109/17483107.2015.1129457] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Tuck-Voon How
- Intelligent Assistive Technology & Systems Lab (IATSL), University of Toronto, Toronto, Canada
| | - Amy S. Hwang
- Intelligent Assistive Technology & Systems Lab (IATSL), University of Toronto, Toronto, Canada
| | - Robin E. A. Green
- Toronto Rehabilitation Institute – University Health Network, Toronto, Canada
- Department of Psychiatry, University of Toronto, Toronto, Canada
| | - Alex Mihailidis
- Intelligent Assistive Technology & Systems Lab (IATSL), University of Toronto, Toronto, Canada
- Toronto Rehabilitation Institute – University Health Network, Toronto, Canada
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58
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Green REA. Editorial: Brain Injury as a Neurodegenerative Disorder. Front Hum Neurosci 2016; 9:615. [PMID: 26778994 PMCID: PMC4700280 DOI: 10.3389/fnhum.2015.00615] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 10/26/2015] [Indexed: 12/14/2022] Open
Affiliation(s)
- Robin E A Green
- Cognitive Neurorehabilitation Sciences Lab, Toronto Rehabilitation InstituteToronto, ON, Canada; Department of Psychiatry, Division of Neurosciences, University of TorontoToronto, ON, Canada
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59
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Structural Image Analysis of the Brain in Neuropsychology Using Magnetic Resonance Imaging (MRI) Techniques. Neuropsychol Rev 2015; 25:224-49. [PMID: 26280751 DOI: 10.1007/s11065-015-9290-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 07/16/2015] [Indexed: 12/11/2022]
Abstract
Magnetic resonance imaging (MRI) of the brain provides exceptional image quality for visualization and neuroanatomical classification of brain structure. A variety of image analysis techniques provide both qualitative as well as quantitative methods to relate brain structure with neuropsychological outcome and are reviewed herein. Of particular importance are more automated methods that permit analysis of a broad spectrum of anatomical measures including volume, thickness and shape. The challenge for neuropsychology is which metric to use, for which disorder and the timing of when image analysis methods are applied to assess brain structure and pathology. A basic overview is provided as to the anatomical and pathoanatomical relations of different MRI sequences in assessing normal and abnormal findings. Some interpretive guidelines are offered including factors related to similarity and symmetry of typical brain development along with size-normalcy features of brain anatomy related to function. The review concludes with a detailed example of various quantitative techniques applied to analyzing brain structure for neuropsychological outcome studies in traumatic brain injury.
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60
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Armstrong RC, Mierzwa AJ, Marion CM, Sullivan GM. White matter involvement after TBI: Clues to axon and myelin repair capacity. Exp Neurol 2015; 275 Pt 3:328-333. [PMID: 25697845 DOI: 10.1016/j.expneurol.2015.02.011] [Citation(s) in RCA: 158] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Revised: 01/15/2015] [Accepted: 02/06/2015] [Indexed: 11/17/2022]
Abstract
Impact-acceleration forces to the head cause traumatic brain injury (TBI) with damage in white matter tracts comprised of long axons traversing the brain. White matter injury after TBI involves both traumatic axonal injury (TAI) and myelin pathology that evolves throughout the post-injury time course. The axon response to initial mechanical forces and secondary insults follows the process of Wallerian degeneration, which initiates as a potentially reversible phase of intra-axonal damage and proceeds to an irreversible phase of axon fragmentation. Distal to sites of axon disconnection, myelin sheaths remain for prolonged periods, which may activate neuroinflammation and inhibit axon regeneration. In addition to TAI, TBI can cause demyelination of intact axons. These evolving features of axon and myelin pathology also represent opportunities for repair. In experimental TBI, demyelinated axons exhibit remyelination, which can serve to both protect axons and facilitate recovery of function. Myelin remodeling may also contribute to neuroplasticity. Efficient clearance of myelin debris is a potential target to attenuate the progression of chronic pathology. During the early phase of Wallerian degeneration, interventions that prevent the transition from reversible damage to axon disconnection warrant the highest priority, based on the poor regenerative capacity of axons in the CNS. Clinical evaluation of TBI will need to address the challenge of accurately detecting the extent and stage of axon damage. Distinguishing the complex white matter changes associated with axons and myelin is necessary for interpreting advanced neuroimaging approaches and for identifying a broader range of therapeutic opportunities to improve outcome after TBI.
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Affiliation(s)
- Regina C Armstrong
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA; Center for Neuroscience and Regenerative Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA; Program in Neuroscience, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA.
| | - Amanda J Mierzwa
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA; Center for Neuroscience and Regenerative Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA
| | - Christina M Marion
- Program in Neuroscience, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA
| | - Genevieve M Sullivan
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA; Center for Neuroscience and Regenerative Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA
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61
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Tomaszczyk JC, Green NL, Frasca D, Colella B, Turner GR, Christensen BK, Green REA. Negative neuroplasticity in chronic traumatic brain injury and implications for neurorehabilitation. Neuropsychol Rev 2014; 24:409-27. [PMID: 25421811 PMCID: PMC4250564 DOI: 10.1007/s11065-014-9273-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Accepted: 09/29/2014] [Indexed: 02/04/2023]
Abstract
Based on growing findings of brain volume loss and deleterious white matter alterations during the chronic stages of injury, researchers posit that moderate-severe traumatic brain injury (TBI) may act to “age” the brain by reducing reserve capacity and inducing neurodegeneration. Evidence that these changes correlate with poorer cognitive and functional outcomes corroborates this progressive characterization of chronic TBI. Borrowing from a framework developed to explain cognitive aging (Mahncke et al., Progress in Brain Research, 157, 81–109, 2006a; Mahncke et al., Proceedings of the National Academy of Sciences of the United States of America, 103(33), 12523–12528, 2006b), we suggest here that environmental factors (specifically environmental impoverishment and cognitive disuse) contribute to a downward spiral of negative neuroplastic change that may modulate the brain changes described above. In this context, we review new literature supporting the original aging framework, and its extrapolation to chronic TBI. We conclude that negative neuroplasticity may be one of the mechanisms underlying cognitive and neural decline in chronic TBI, but that there are a number of points of intervention that would permit mitigation of this decline and better long-term clinical outcomes.
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Affiliation(s)
- Jennifer C Tomaszczyk
- Research Department, Toronto Rehabilitation Institute - University Health Network, Toronto, ON, Canada
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62
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Keightley ML, Sinopoli KJ, Davis KD, Mikulis DJ, Wennberg R, Tartaglia MC, Chen JK, Tator CH. Is there evidence for neurodegenerative change following traumatic brain injury in children and youth? A scoping review. Front Hum Neurosci 2014; 8:139. [PMID: 24678292 PMCID: PMC3958726 DOI: 10.3389/fnhum.2014.00139] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Accepted: 02/24/2014] [Indexed: 11/13/2022] Open
Abstract
While generalized cerebral atrophy and neurodegenerative change following traumatic brain injury (TBI) is well recognized in adults, it remains comparatively understudied in the pediatric population, suggesting that research should address the potential for neurodegenerative change in children and youth following TBI. This focused review examines original research findings documenting evidence for neurodegenerative change following TBI of all severities in children and youth. Our relevant inclusion and exclusion criteria identified a total of 16 articles for review. Taken together, the studies reviewed suggest there is evidence for long-term neurodegenerative change following TBI in children and youth. In particular both cross-sectional and longitudinal studies revealed volume loss in selected brain regions including the hippocampus, amygdala, globus pallidus, thalamus, periventricular white matter, cerebellum, and brain stem as well as overall decreased whole brain volume and increased CSF and ventricular space. Diffusion Tensor Imaging (DTI) studies also report evidence for decreased cellular integrity, particularly in the corpus callosum. Sensitivity of the hippocampus and deep limbic structures in pediatric populations are similar to findings in the adult literature and we consider the data supporting these changes as well as the need to investigate the possibility of neurodegenerative onset in childhood associated with mild traumatic brain injury (mTBI).
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Affiliation(s)
- Michelle L Keightley
- Bloorview Research Institute, Holland Bloorview Kids Rehabilitation Hospital Toronto, ON, Canada ; Department of Occupational Science and Occupational Therapy, University of Toronto Toronto, ON, Canada ; Graduate Department of Rehabilitation Science, University of Toronto ON, Canada ; Department of Psychology, University of Toronto ON, Canada ; Cognitive Neurorehabilitation Sciences, Toronto Rehabilitation Institute Toronto, ON, Canada
| | - Katia J Sinopoli
- Bloorview Research Institute, Holland Bloorview Kids Rehabilitation Hospital Toronto, ON, Canada ; Department of Psychology and Division of Neurology, Sickids Hospital for Sick Children Toronto, ON, Canada
| | - Karen D Davis
- Division of Brain, Imaging and Behaviour - Systems Neuroscience, Toronto Western Research Institute, University Health Network Toronto, ON, Canada ; Department of Surgery and Institute of Medical Science, University of Toronto Toronto, ON, Canada
| | - David J Mikulis
- Division of Brain, Imaging and Behaviour - Systems Neuroscience, Toronto Western Research Institute, University Health Network Toronto, ON, Canada
| | - Richard Wennberg
- Krembil Neuroscience Centre, Toronto Western Hospital, University Health Network and University of Toronto Toronto, ON, Canada
| | - Maria C Tartaglia
- Krembil Neuroscience Centre, Toronto Western Hospital, University Health Network and University of Toronto Toronto, ON, Canada
| | - Jen-Kai Chen
- Neuropsychology/Cognitive Neuroscience Unit, Montreal Neurological Institute Montreal, QC, Canada
| | - Charles H Tator
- Krembil Neuroscience Centre, Toronto Western Hospital, University Health Network and University of Toronto Toronto, ON, Canada
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