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Poulen G, Perrin FE. Advances in spinal cord injury: insights from non-human primates. Neural Regen Res 2024; 19:2354-2364. [PMID: 38526271 PMCID: PMC11090432 DOI: 10.4103/nrr.nrr-d-23-01505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 11/13/2023] [Accepted: 12/22/2023] [Indexed: 03/26/2024] Open
Abstract
Spinal cord injury results in significant sensorimotor deficits, currently, there is no curative treatment for the symptoms induced by spinal cord injury. Basic and pre-clinical research on spinal cord injury relies on the development and characterization of appropriate animal models. These models should replicate the symptoms observed in human, allowing for the exploration of functional deficits and investigation into various aspects of physiopathology of spinal cord injury. Non-human primates, due to their close phylogenetic association with humans, share more neuroanatomical, genetic, and physiological similarities with humans than rodents. Therefore, the responses to spinal cord injury in nonhuman primates most likely resemble the responses to traumatism in humans. In this review, we will discuss nonhuman primate models of spinal cord injury, focusing on in vivo assessments, including behavioral tests, magnetic resonance imaging, and electrical activity recordings, as well as ex vivo histological analyses. Additionally, we will present therapeutic strategies developed in non-human primates and discuss the unique specificities of non-human primate models of spinal cord injury.
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Affiliation(s)
- Gaetan Poulen
- University of Montpellier, INSERM, EPHE, Montpellier, France
- Department of Neurosurgery, Gui de Chauliac Hospital, Montpellier University Medical Center, Montpellier, France
| | - Florence E. Perrin
- University of Montpellier, INSERM, EPHE, Montpellier, France
- Institut Universitaire de France (IUF), Paris, France
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2
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Behavioral recovery after a spinal deafferentation injury in monkeys does not correlate with extent of corticospinal sprouting. Behav Brain Res 2022; 416:113533. [PMID: 34453971 PMCID: PMC8492525 DOI: 10.1016/j.bbr.2021.113533] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 07/26/2021] [Accepted: 08/13/2021] [Indexed: 01/09/2023]
Abstract
A long held view in the spinal cord injury field is that corticospinal terminal sprouting is needed for new connections to form, that then mediate behavioral recovery. This makes sense, but tells us little about the relationship between corticospinal sprouting extent and recovery potential. The inference has been that more extensive axonal sprouting predicts greater recovery, though there is little evidence to support this. Here we addressed this by comparing behavioral data from monkeys that had received one of two established deafferentation spinal injury models in monkeys (Darian-Smith et al., 2014, Fisher et al., 2019, 2020). Both injuries cut similar afferent pools supplying the thumb, index and middle fingers of one hand but each resulted in a very different corticospinal tract (CST) sprouting response. Following a cervical dorsal root lesion, the somatosensory CST retracted significantly, while the motor CST stayed largely intact. In contrast, when a dorsal column lesion was combined with the DRL, somatosensory and motor CSTs sprouted dramatically within the cervical cord. How these two responses relate to the behavioral outcome was not clear. Here we analyzed the behavioral outcome for the two lesions, and provide a clear example that sprouting extent does not track with behavioral recovery.
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3
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Liao C, Qi H, Reed JL, Jeoung H, Kaas JH. Corticocuneate projections are altered after spinal cord dorsal column lesions in New World monkeys. J Comp Neurol 2021; 529:1669-1702. [PMID: 33029803 PMCID: PMC7987845 DOI: 10.1002/cne.25050] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 10/02/2020] [Accepted: 10/03/2020] [Indexed: 12/31/2022]
Abstract
Recovery of responses to cutaneous stimuli in the area 3b hand cortex of monkeys after dorsal column lesions (DCLs) in the cervical spinal cord relies on neural rewiring in the cuneate nucleus (Cu) over time. To examine whether the corticocuneate projections are modified during recoveries after the DCL, we injected cholera toxin subunit B into the hand representation in Cu to label the cortical neurons after various recovery times, and related results to the recovery of neural responses in the affected area 3b hand cortex. In normal New World monkeys, labeled neurons were predominately distributed in the hand regions of contralateral areas 3b, 3a, 1 and 2, parietal ventral (PV), secondary somatosensory cortex (S2), and primary motor cortex (M1), with similar distributions in the ipsilateral cortex in significantly smaller numbers. In monkeys with short-term recoveries, the area 3b hand neurons were unresponsive or responded weakly to touch on the hand, while the cortical labeling pattern was largely unchanged. After longer recoveries, the area 3b hand neurons remained unresponsive, or responded to touch on the hand or somatotopically abnormal parts, depending on the lesion extent. The distributions of cortical labeled neurons were much more widespread than the normal pattern in both hemispheres, especially when lesions were incomplete. The proportion of labeled neurons in the contralateral area 3b hand cortex was not correlated with the functional reactivation in the area 3b hand cortex. Overall, our findings indicated that corticocuneate inputs increase during the functional recovery, but their functional role is uncertain.
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Affiliation(s)
- Chia‐Chi Liao
- Department of Psychology Vanderbilt University Nashville Tennessee USA
| | - Hui‐Xin Qi
- Department of Psychology Vanderbilt University Nashville Tennessee USA
| | - Jamie L. Reed
- Department of Psychology Vanderbilt University Nashville Tennessee USA
| | - Ha‐Seul Jeoung
- Department of Psychology Vanderbilt University Nashville Tennessee USA
| | - Jon H. Kaas
- Department of Psychology Vanderbilt University Nashville Tennessee USA
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4
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Qi HX, Liao CC, Reed JL, Kaas JH. Reorganization of Higher-Order Somatosensory Cortex After Sensory Loss from Hand in Squirrel Monkeys. Cereb Cortex 2020; 29:4347-4365. [PMID: 30590401 DOI: 10.1093/cercor/bhy317] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Revised: 10/18/2018] [Accepted: 11/20/2018] [Indexed: 12/31/2022] Open
Abstract
Unilateral dorsal column lesions (DCL) at the cervical spinal cord deprive the hand regions of somatosensory cortex of tactile activation. However, considerable cortical reactivation occurs over weeks to months of recovery. While most studies focused on the reactivation of primary somatosensory area 3b, here, for the first time, we address how the higher-order somatosensory cortex reactivates in the same monkeys after DCL that vary across cases in completeness, post-lesion recovery times, and types of treatments. We recorded neural responses to tactile stimulation in areas 3a, 3b, 1, secondary somatosensory cortex (S2), parietal ventral (PV), and occasionally areas 2/5. Our analysis emphasized comparisons of the responsiveness, somatotopy, and receptive field size between areas 3b, 1, and S2/PV across DCL conditions and recovery times. The results indicate that the extents of the reactivation in higher-order somatosensory areas 1 and S2/PV closely reflect the reactivation in primary somatosensory cortex. Responses in higher-order areas S2 and PV can be stronger than those in area 3b, thus suggesting converging or alternative sources of inputs. The results also provide evidence that both primary and higher-order fields are effectively activated after long recovery times as well as after behavioral and electrocutaneous stimulation interventions.
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Affiliation(s)
- Hui-Xin Qi
- Department of Psychology, Vanderbilt University, Nashville, TN, USA
| | - Chia-Chi Liao
- Department of Psychology, Vanderbilt University, Nashville, TN, USA
| | - Jamie L Reed
- Department of Psychology, Vanderbilt University, Nashville, TN, USA
| | - Jon H Kaas
- Department of Psychology, Vanderbilt University, Nashville, TN, USA
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5
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Vallotton K, Huber E, Sutter R, Curt A, Hupp M, Freund P. Width and neurophysiologic properties of tissue bridges predict recovery after cervical injury. Neurology 2019; 92:e2793-e2802. [PMID: 31092621 PMCID: PMC6598793 DOI: 10.1212/wnl.0000000000007642] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 02/07/2019] [Indexed: 12/11/2022] Open
Abstract
OBJECTIVE To assess whether preserved dorsal and ventral midsagittal tissue bridges after traumatic cervical spinal cord injury (SCI) encode tract-specific electrophysiologic properties and are predictive of appropriate recovery. METHODS In this longitudinal study, we retrospectively assessed MRI scans at 1 month after SCI that provided data on width and location (dorsal vs ventral) of midsagittal tissue bridges in 28 tetraplegic patients. Regression analysis assessed associations between midsagittal tissue bridges and motor- and sensory-specific electrophysiologic recordings and appropriate outcome measures at 12 months after SCI. RESULTS Greater width of dorsal midsagittal tissue bridges at 1 month after SCI identified patients who were classified as being sensory incomplete at 12 months after SCI (p = 0.025), had shorter sensory evoked potential (SEP) latencies (r = -0.57, p = 0.016), and had greater SEP amplitudes (r = 0.61, p = 0.001). Greater width of dorsal tissue bridges predicted better light-touch score at 12 months (r = 0.40, p = 0.045) independently of baseline clinical score and ventral tissue bridges. Greater width of ventral midsagittal tissue bridges at 1 month identified patients who were classified as being motor incomplete at 12 months (p = 0.002), revealed shorter motor evoked potential (MEP) latencies (r = -0.54, p = 0.044), and had greater ratios of MEP amplitude to compound muscle action potential amplitude (r = 0.56, p = 0.005). Greater width of ventral tissue bridges predicted better lower extremity motor scores at 12 months (r = 0.41, p = 0.035) independently of baseline clinical score and dorsal tissue bridges. CONCLUSION Midsagittal tissue bridges, detectable early after SCI, underwrite tract-specific electrophysiologic communication and are predictors of appropriate sensorimotor recovery. Neuroimaging biomarkers of midsagittal tissue bridges may be integrated into the diagnostic workup, prediction of recovery, and patients' stratification in clinical trials.
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Affiliation(s)
- Kevin Vallotton
- From the Spinal Cord Injury Center (K.V., E.H., A.C., M.H., P.F.) and Department of Radiology (R.S.), Balgrist University Hospital; University of Zurich (K.V., E.H., A.C., M.H., P.F., R.S.), Switzerland; Wellcome Trust Centre for Neuroimaging (P.F.) and Department of Brain Repair and Rehabilitation (P.F.), UCL Institute of Neurology, University College London, UK; and Department of Neurophysics (P.F.), Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Eveline Huber
- From the Spinal Cord Injury Center (K.V., E.H., A.C., M.H., P.F.) and Department of Radiology (R.S.), Balgrist University Hospital; University of Zurich (K.V., E.H., A.C., M.H., P.F., R.S.), Switzerland; Wellcome Trust Centre for Neuroimaging (P.F.) and Department of Brain Repair and Rehabilitation (P.F.), UCL Institute of Neurology, University College London, UK; and Department of Neurophysics (P.F.), Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Reto Sutter
- From the Spinal Cord Injury Center (K.V., E.H., A.C., M.H., P.F.) and Department of Radiology (R.S.), Balgrist University Hospital; University of Zurich (K.V., E.H., A.C., M.H., P.F., R.S.), Switzerland; Wellcome Trust Centre for Neuroimaging (P.F.) and Department of Brain Repair and Rehabilitation (P.F.), UCL Institute of Neurology, University College London, UK; and Department of Neurophysics (P.F.), Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Armin Curt
- From the Spinal Cord Injury Center (K.V., E.H., A.C., M.H., P.F.) and Department of Radiology (R.S.), Balgrist University Hospital; University of Zurich (K.V., E.H., A.C., M.H., P.F., R.S.), Switzerland; Wellcome Trust Centre for Neuroimaging (P.F.) and Department of Brain Repair and Rehabilitation (P.F.), UCL Institute of Neurology, University College London, UK; and Department of Neurophysics (P.F.), Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Markus Hupp
- From the Spinal Cord Injury Center (K.V., E.H., A.C., M.H., P.F.) and Department of Radiology (R.S.), Balgrist University Hospital; University of Zurich (K.V., E.H., A.C., M.H., P.F., R.S.), Switzerland; Wellcome Trust Centre for Neuroimaging (P.F.) and Department of Brain Repair and Rehabilitation (P.F.), UCL Institute of Neurology, University College London, UK; and Department of Neurophysics (P.F.), Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Patrick Freund
- From the Spinal Cord Injury Center (K.V., E.H., A.C., M.H., P.F.) and Department of Radiology (R.S.), Balgrist University Hospital; University of Zurich (K.V., E.H., A.C., M.H., P.F., R.S.), Switzerland; Wellcome Trust Centre for Neuroimaging (P.F.) and Department of Brain Repair and Rehabilitation (P.F.), UCL Institute of Neurology, University College London, UK; and Department of Neurophysics (P.F.), Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany.
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6
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Qian J, Wu W, Xiong W, Chai Z, Xu XM, Jin X. Longitudinal Optogenetic Motor Mapping Revealed Structural and Functional Impairments and Enhanced Corticorubral Projection after Contusive Spinal Cord Injury in Mice. J Neurotrauma 2018; 36:485-499. [PMID: 29848155 DOI: 10.1089/neu.2018.5713] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Current evaluation of impairment and repair after spinal cord injury (SCI) is largely dependent on behavioral assessment and histological analysis of injured tissue and pathways. Here, we evaluated whether transcranial optogenetic mapping of motor cortex could reflect longitudinal structural and functional damage and recovery after SCI. In Thy1-Channelrhodopsin2 transgenic mice, repeated motor mappings were made by recording optogenetically evoked electromyograms (EMGs) of a hindlimb at baseline and 1 day and 2, 4, and 6 weeks after mild, moderate, and severe spinal cord contusion. Injuries caused initial decreases in EMG amplitude, losses of motor map, and subsequent partial recoveries, all of which corresponded to injury severity. Reductions in map size were positively correlated with motor performance, as measured by Basso Mouse Scale, rota-rod, and grid walk tests, at different time points, as well as with lesion area at spinal cord epicenter at 6 weeks post-SCI. Retrograde tracing with Fluoro-Gold showed decreased numbers of cortico- and rubrospinal neurons, with the latter being negatively correlated with motor map size. Combined retro- and anterograde tracing and immunostaining revealed more neurons activated in red nucleus by cortical stimulation and enhanced corticorubral axons and synapses in red nucleus after SCI. Electrophysiological recordings showed lower threshold and higher amplitude of corticorubral synaptic response after SCI. We conclude that transcranial optogenetic motor mapping is sensitive and efficient for longitudinal evaluation of impairment and plasticity of SCI, and that spinal cord contusion induces stronger anatomical and functional corticorubral connection that may contribute to spontaneous recovery of motor function.
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Affiliation(s)
- Jun Qian
- 1 Department of Anatomy and Cell Biology & Department of Neurological Surgery, Spinal Cord and Brain Injury Research Group, Stark Neuroscience Research Institute, Indiana University School of Medicine, Indianapolis, Indiana.,2 Department of Spinal Surgery and Orthopedics, The First Affiliated Hospital of Anhui Medical University, Hefei, China
| | - Wei Wu
- 1 Department of Anatomy and Cell Biology & Department of Neurological Surgery, Spinal Cord and Brain Injury Research Group, Stark Neuroscience Research Institute, Indiana University School of Medicine, Indianapolis, Indiana
| | - Wenhui Xiong
- 1 Department of Anatomy and Cell Biology & Department of Neurological Surgery, Spinal Cord and Brain Injury Research Group, Stark Neuroscience Research Institute, Indiana University School of Medicine, Indianapolis, Indiana
| | - Zhi Chai
- 3 Research Center of Neurobiology, Shanxi University of Traditional Chinese Medicine, Taiyuan, China
| | - Xiao-Ming Xu
- 1 Department of Anatomy and Cell Biology & Department of Neurological Surgery, Spinal Cord and Brain Injury Research Group, Stark Neuroscience Research Institute, Indiana University School of Medicine, Indianapolis, Indiana
| | - Xiaoming Jin
- 1 Department of Anatomy and Cell Biology & Department of Neurological Surgery, Spinal Cord and Brain Injury Research Group, Stark Neuroscience Research Institute, Indiana University School of Medicine, Indianapolis, Indiana
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7
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O'Shea DJ, Kalanithi P, Ferenczi EA, Hsueh B, Chandrasekaran C, Goo W, Diester I, Ramakrishnan C, Kaufman MT, Ryu SI, Yeom KW, Deisseroth K, Shenoy KV. Development of an optogenetic toolkit for neural circuit dissection in squirrel monkeys. Sci Rep 2018; 8:6775. [PMID: 29712920 PMCID: PMC5928036 DOI: 10.1038/s41598-018-24362-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Accepted: 04/03/2018] [Indexed: 01/01/2023] Open
Abstract
Optogenetic tools have opened a rich experimental landscape for understanding neural function and disease. Here, we present the first validation of eight optogenetic constructs driven by recombinant adeno-associated virus (AAV) vectors and a WGA-Cre based dual injection strategy for projection targeting in a widely-used New World primate model, the common squirrel monkey Saimiri sciureus. We observed opsin expression around the local injection site and in axonal projections to downstream regions, as well as transduction to thalamic neurons, resembling expression patterns observed in macaques. Optical stimulation drove strong, reliable excitatory responses in local neural populations for two depolarizing opsins in anesthetized monkeys. Finally, we observed continued, healthy opsin expression for at least one year. These data suggest that optogenetic tools can be readily applied in squirrel monkeys, an important first step in enabling precise, targeted manipulation of neural circuits in these highly trainable, cognitively sophisticated animals. In conjunction with similar approaches in macaques and marmosets, optogenetic manipulation of neural circuits in squirrel monkeys will provide functional, comparative insights into neural circuits which subserve dextrous motor control as well as other adaptive behaviors across the primate lineage. Additionally, development of these tools in squirrel monkeys, a well-established model system for several human neurological diseases, can aid in identifying novel treatment strategies.
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Affiliation(s)
- Daniel J O'Shea
- Neurosciences Program, Stanford University, Stanford, CA, USA.
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA.
| | - Paul Kalanithi
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA
- Department of Neurosurgery, Stanford University, Stanford, CA, USA
| | | | - Brian Hsueh
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | | | - Werapong Goo
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Ilka Diester
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA
- Department of Bioengineering, Stanford University, Stanford, CA, USA
- Department of Otophysiologie, Albert Ludwig University of Freiburg, Freiburg im Breisgau, Germany
- BrainLinks-BrainTools, Albert Ludwig University of Freiburg, Freiburg im Breisgau, Germany
| | | | - Matthew T Kaufman
- Neurosciences Program, Stanford University, Stanford, CA, USA
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA
| | - Stephen I Ryu
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA
- Palo Alto Medical Foundation, Palo Alto, CA, USA
| | - Kristen W Yeom
- Department of Radiology, Stanford University, Stanford, CA, USA
| | - Karl Deisseroth
- Department of Bioengineering, Stanford University, Stanford, CA, USA
- Department of Psychiatry and Behavioral Science, Stanford University, Stanford, CA, USA
- Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA
| | - Krishna V Shenoy
- Neurosciences Program, Stanford University, Stanford, CA, USA
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA
- Department of Bioengineering, Stanford University, Stanford, CA, USA
- Department of Neurobiology, Stanford University, Stanford, CA, USA
- Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA
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8
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Grabher P, Mohammadi S, David G, Freund P. Neurodegeneration in the Spinal Ventral Horn Prior to Motor Impairment in Cervical Spondylotic Myelopathy. J Neurotrauma 2017; 34:2329-2334. [PMID: 28462691 DOI: 10.1089/neu.2017.4980] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Remote gray matter pathology has been suggested rostral to the compression site in cervical spondylotic myelopathy (CSM). We therefore assessed neurodegeneration in the gray matter ventral and dorsal horns. Twenty patients with CSM and 18 healthy subjects underwent a high-resolution structural and diffusion magnetic resonance imaging protocol at vertebra C2/C3. Patients received comprehensive clinical assessments. T2*-weighted data provided cross-sectional area measurements of gray matter ventral and dorsal horns to identify atrophy. At the identical location, mean diffusivity (MD) and fractional anisotropy (FA) determined the microstructural integrity. Finally, the relationships between neurodegeneration occurring in the gray and white matter and clinical impairment were investigated. Patients suffered from mild-to-moderate CSM with mainly sensory impairment. In the ventral horns, cross-sectional area was not reduced (p = 0.863) but MD was increased (p = 0.045). The magnitude of MD changes within the ventral horn was associated with white matter diffusivity changes (MD: p = 0.013; FA: p = 0.028) within the lateral corticospinal tract. In contrast, dorsal horn cross-sectional area was reduced by 16.0% (p < 0.001) without alterations in diffusivity indices, compared with controls. No associations between the magnitude of ventral and dorsal horn neurodegeneration and clinical impairment were evident. Focal cord gray matter pathology is evident remote to the compression site in vivo in CSM patients. Microstructural changes in the ventral horns (i.e., motoneurons) related to corticospinal tract integrity in the absence of atrophy and marked motor impairment. Dorsal horn atrophy corresponded to main clinical representation of sensory impairment. Thus, neuroimaging biomarkers of cord gray matter integrity reveal focal neurodegeneration prior to marked clinical impairment and thus could serve as predictors of ensuing impairment in CSM patients.
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Affiliation(s)
- Patrick Grabher
- 1 Spinal Cord Injury Center Balgrist, University Hospital Zurich, University of Zurich , Zurich, Switzerland
| | - Siawoosh Mohammadi
- 2 Department of Systems Neuroscience, University Medical Center Hamburg-Eppendorf , Hamburg, Germany .,3 Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College London , London, United Kingdom .,4 Department of Neurophysics, Max Planck Institute for Human Cognitive and Brain Sciences , Leipzig, Germany
| | - Gergely David
- 1 Spinal Cord Injury Center Balgrist, University Hospital Zurich, University of Zurich , Zurich, Switzerland
| | - Patrick Freund
- 1 Spinal Cord Injury Center Balgrist, University Hospital Zurich, University of Zurich , Zurich, Switzerland .,3 Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College London , London, United Kingdom .,4 Department of Neurophysics, Max Planck Institute for Human Cognitive and Brain Sciences , Leipzig, Germany .,5 Department of Brain Repair and Rehabilitation, Institute of Neurology, University College London , London, United Kingdom
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9
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Wang F, Zu Z, Wu R, Wu TL, Gore JC, Chen LM. MRI evaluation of regional and longitudinal changes in Z-spectra of injured spinal cord of monkeys. Magn Reson Med 2017; 79:1070-1082. [PMID: 28547862 DOI: 10.1002/mrm.26756] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Revised: 04/21/2017] [Accepted: 04/22/2017] [Indexed: 01/21/2023]
Abstract
PURPOSE In principle, MR methods that exploit magnetization transfer (MT) may be used to quantify changes in the molecular composition of tissues after injury. The ability to track such changes in injured spinal cord may allow more precise assessment of the state of neural tissues. METHODS Z-Spectra were obtained from the cervical spinal cord before and after a unilateral dorsal column lesion in monkeys at 9.4T. The amplitudes of chemical exchange saturation transfer (CEST) and nuclear Overhauser enhancement (NOE) effects from multiple proton pools, along with nonspecific semisolid MT effects from immobile macromolecules, were quantified using a five-peak Lorenzian fitting of each Z-spectrum. RESULTS Abnormal tissues/cysts that formed around lesion sites exhibited relatively low correlations between their Z-spectra and that of normal gray matter (GM). Compared with normal GM, cysts showed strong CEST but weak semisolid MT and NOE effects after injury. The abnormal tissues around lesion sites were heterogeneous and showed different regional Z-spectra. Different regional correlations between proton pools were observed. Longitudinally, injured spinal cord tissue exhibited remarkable recovery in all subjects. CONCLUSION Characterization of multiple proton pools from Z-spectra permitted noninvasive, regional, quantitative assessments of changes in tissue composition of injured spinal cord over time. Magn Reson Med 79:1070-1082, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Feng Wang
- Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA
| | - Zhongliang Zu
- Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA
| | - Ruiqi Wu
- Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA
| | - Tung-Lin Wu
- Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA
| | - John C Gore
- Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA.,Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA
| | - Li Min Chen
- Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA
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10
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Chen LM, Yang PF, Wang F, Mishra A, Shi Z, Wu R, Wu TL, Wilson GH, Ding Z, Gore JC. Biophysical and neural basis of resting state functional connectivity: Evidence from non-human primates. Magn Reson Imaging 2017; 39:71-81. [PMID: 28161319 DOI: 10.1016/j.mri.2017.01.020] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Accepted: 01/27/2017] [Indexed: 12/17/2022]
Abstract
Functional MRI (fMRI) has evolved from simple observations of regional changes in MRI signals caused by cortical activity induced by a task or stimulus, to task-free acquisitions of images in a resting state. Such resting state signals contain low frequency fluctuations which may be correlated between voxels, and strongly correlated regions are deemed to reflect functional connectivity within synchronized circuits. Resting state functional connectivity (rsFC) measures have been widely adopted by the neuroscience community, and are being used and interpreted as indicators of intrinsic neural circuits and their functional states in a broad range of applications, both basic and clinical. However, there has been relatively little work reported that validates whether inter-regional correlations in resting state fluctuations of fMRI (rsfMRI) signals actually measure functional connectivity between brain regions, or to establish how MRI data correlate with other metrics of functional connectivity. In this mini-review, we summarize recent studies of rsFC within mesoscopic scale cortical networks (100μm-10mm) within a well defined functional region of primary somatosensory cortex (S1), as well as spinal cord and brain white matter in non-human primates, in which we have measured spatial patterns of resting state correlations and validated their interpretation with electrophysiological signals and anatomic connections. Moreover, we emphasize that low frequency correlations are a general feature of neural systems, as evidenced by their presence in the spinal cord as well as white matter. These studies demonstrate the valuable role of high field MRI and invasive measurements in an animal model to inform the interpretation of human imaging studies.
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Affiliation(s)
- Li Min Chen
- Vanderbilt University Institute of Imaging Science, Nashville, TN 37232, USA; Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
| | - Pai-Feng Yang
- Vanderbilt University Institute of Imaging Science, Nashville, TN 37232, USA; Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Feng Wang
- Vanderbilt University Institute of Imaging Science, Nashville, TN 37232, USA; Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Arabinda Mishra
- Vanderbilt University Institute of Imaging Science, Nashville, TN 37232, USA; Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Zhaoyue Shi
- Vanderbilt University Institute of Imaging Science, Nashville, TN 37232, USA; Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37232, USA
| | - Ruiqi Wu
- Vanderbilt University Institute of Imaging Science, Nashville, TN 37232, USA; Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Tung-Lin Wu
- Vanderbilt University Institute of Imaging Science, Nashville, TN 37232, USA; Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37232, USA
| | - George H Wilson
- Vanderbilt University Institute of Imaging Science, Nashville, TN 37232, USA; Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Zhaohua Ding
- Vanderbilt University Institute of Imaging Science, Nashville, TN 37232, USA; Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37232, USA; Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, TN 37232, USA
| | - John C Gore
- Vanderbilt University Institute of Imaging Science, Nashville, TN 37232, USA; Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37232, USA.
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