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Frey VN, Langthaler PB, Renz N, Zimmermann G, Höhn C, Schwenker K, Thomschewski A, Kunz AB, Höller Y, Nardone R, Trinka E. Influence of sports on cortical excitability in patients with spinal cord injury: a TMS study. FRONTIERS IN MEDICAL TECHNOLOGY 2024; 6:1297552. [PMID: 38812566 PMCID: PMC11133579 DOI: 10.3389/fmedt.2024.1297552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Accepted: 04/19/2024] [Indexed: 05/31/2024] Open
Abstract
Background Patients with spinal cord injury (SCI) show abnormal cortical excitability that might be caused by deafferentation. We hypothesize a reduced short-interval intracortical inhibition preceding movement in patients with SCI compared with healthy participants. In addition, we expect that neuroplasticity induced by different types of sports can modulate intracortical inhibition during movement preparation in patients with SCI. Methods We used a reaction test and paired-pulse transcranial magnetic stimulation to record cortical excitability, assessed by measuring amplitudes of motor-evoked potentials in preparation of movement. The participants were grouped as patients with SCI practicing wheelchair dancing (n = 7), other sports (n = 6), no sports (n = 9), and healthy controls (n = 24). Results There were neither significant differences between healthy participants and the patients nor between the different patient groups. A non-significant trend (p = .238), showed that patients engaged in sports have a stronger increase in cortical excitability compared with patients of the non-sportive group, while the patients in the other sports group expressed the highest increase in cortical excitability. Conclusion The small sample sizes limit the statistical power of the study, but the trending effect warrants further investigation of different sports on the neuroplasticity in patients with SCI. It is not clear how neuroplastic changes impact the sensorimotor output of the affected extremities in a patient. This needs to be followed up in further studies with a greater sample size.
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Affiliation(s)
- Vanessa N. Frey
- Department of Neurology, Neurointensive Care and Neurorehabilitation, Member of the European Reference Network EpiCARE, Christian Doppler University Hospital, Centre for Cognitive Neuroscience, Paracelsus Medical University Salzburg, Salzburg, Austria
- Spinal Cord Injury and Tissue Regeneration Center, Paracelsus Medical University, Salzburg, Austria
| | - Patrick B. Langthaler
- Department of Neurology, Neurointensive Care and Neurorehabilitation, Member of the European Reference Network EpiCARE, Christian Doppler University Hospital, Centre for Cognitive Neuroscience, Paracelsus Medical University Salzburg, Salzburg, Austria
- Spinal Cord Injury and Tissue Regeneration Center, Paracelsus Medical University, Salzburg, Austria
- Department of Mathematics, Paris Lodron University, Salzburg, Austria
| | - Nora Renz
- Department of Neurology, Neurointensive Care and Neurorehabilitation, Member of the European Reference Network EpiCARE, Christian Doppler University Hospital, Centre for Cognitive Neuroscience, Paracelsus Medical University Salzburg, Salzburg, Austria
- Spinal Cord Injury and Tissue Regeneration Center, Paracelsus Medical University, Salzburg, Austria
| | - Georg Zimmermann
- Department of Neurology, Neurointensive Care and Neurorehabilitation, Member of the European Reference Network EpiCARE, Christian Doppler University Hospital, Centre for Cognitive Neuroscience, Paracelsus Medical University Salzburg, Salzburg, Austria
- IDA Lab Salzburg, Team Biostatistics and Big Medical Data, Paracelsus Medical University Salzburg, Salzburg, Austria
| | - Christopher Höhn
- Laboratory for Sleep, Cognition and Consciousness Research, Department of Psychology, Centre for Cognitive Neuroscience, University of Salzburg, Salzburg, Austria
| | - Kerstin Schwenker
- Department of Neurology, Neurointensive Care and Neurorehabilitation, Member of the European Reference Network EpiCARE, Christian Doppler University Hospital, Centre for Cognitive Neuroscience, Paracelsus Medical University Salzburg, Salzburg, Austria
- Spinal Cord Injury and Tissue Regeneration Center, Paracelsus Medical University, Salzburg, Austria
- Karl Landsteiner Institute for Neurorehabilitation and Space Neurology Salzburg, Salzburg, Austria
| | - Aljoscha Thomschewski
- Department of Neurology, Neurointensive Care and Neurorehabilitation, Member of the European Reference Network EpiCARE, Christian Doppler University Hospital, Centre for Cognitive Neuroscience, Paracelsus Medical University Salzburg, Salzburg, Austria
- Spinal Cord Injury and Tissue Regeneration Center, Paracelsus Medical University, Salzburg, Austria
| | - Alexander B. Kunz
- Department of Neurology, Neurointensive Care and Neurorehabilitation, Member of the European Reference Network EpiCARE, Christian Doppler University Hospital, Centre for Cognitive Neuroscience, Paracelsus Medical University Salzburg, Salzburg, Austria
- Karl Landsteiner Institute for Neurorehabilitation and Space Neurology Salzburg, Salzburg, Austria
| | - Yvonne Höller
- Department of Neurology, Neurointensive Care and Neurorehabilitation, Member of the European Reference Network EpiCARE, Christian Doppler University Hospital, Centre for Cognitive Neuroscience, Paracelsus Medical University Salzburg, Salzburg, Austria
- Faculty of Psychology, University of Akureyri, Akureyri, Iceland
| | - Raffaele Nardone
- Department of Neurology, Neurointensive Care and Neurorehabilitation, Member of the European Reference Network EpiCARE, Christian Doppler University Hospital, Centre for Cognitive Neuroscience, Paracelsus Medical University Salzburg, Salzburg, Austria
- Spinal Cord Injury and Tissue Regeneration Center, Paracelsus Medical University, Salzburg, Austria
- Karl Landsteiner Institute for Neurorehabilitation and Space Neurology Salzburg, Salzburg, Austria
- Department of Neurology, Tappeiner Hospital, Meran, Italy
| | - Eugen Trinka
- Department of Neurology, Neurointensive Care and Neurorehabilitation, Member of the European Reference Network EpiCARE, Christian Doppler University Hospital, Centre for Cognitive Neuroscience, Paracelsus Medical University Salzburg, Salzburg, Austria
- Spinal Cord Injury and Tissue Regeneration Center, Paracelsus Medical University, Salzburg, Austria
- Karl Landsteiner Institute for Neurorehabilitation and Space Neurology Salzburg, Salzburg, Austria
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Sanganahalli BG, Pavuluri S, Chitturi J, Herman P, Elkabes S, Heary R, Hyder F, Kannurpatti SS. Lateralized Supraspinal Functional Connectivity Correlate with Pain and Motor Dysfunction in Rat Hemicontusion Cervical Spinal Cord Injury. Neurotrauma Rep 2022; 3:421-432. [PMID: 36337081 PMCID: PMC9622206 DOI: 10.1089/neur.2022.0040] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Afferent nociceptive activity in the reorganizing spinal cord after SCI influences supraspinal regions to establish pain. Clinical evidence of poor motor functional recovery in SCI patients with pain, led us to hypothesize that sensory-motor integration transforms into sensory-motor interference to manifest pain. This was tested by investigating supraspinal changes in a rat model of hemicontusion cervical SCI. Animals displayed ipsilateral forelimb motor dysfunction and pain, which persisted at 6 weeks after SCI. Using resting state fMRI at 8 weeks after SCI, RSFC across 14 ROIs involved in nociception, indicated lateral differences with a relatively weaker right-right connectivity (deafferented-contralateral) compared to left-left (unaffected-ipsilateral). However, the sensory (S1) and motor (M1/M2) networks showed greater RSFC using right hemisphere ROI seeds when compared to left. Voxel seeds from the somatosensory forelimb (S1FL) and M1/M2 representations reproduced the SCI-induced sensory and motor RSFC enhancements observed using the ROI seeds. Larger local connectivity occurred in the right sensory and motor networks amidst a decreasing overall local connectivity. This maladaptive reorganization of the right (deafferented) hemisphere localized the sensory component of pain emerging from the ipsilateral forepaw. A significant expansion of the sensory and motor network s overlap occurred globally after SCI when compared to sham, supporting the hypothesis that sensory and motor interference manifests pain. Voxel-seed based analysis revealed greater sensory and motor network overlap in the left hemisphere when compared to the right. This left predominance of the overlap suggested relatively larger pain processing in the unaffected hemisphere, when compared to the deafferented side.
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Affiliation(s)
- Basavaraju G. Sanganahalli
- Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Swathi Pavuluri
- Department of Radiology, Rutgers Biomedical and Health Sciences–New Jersey Medical School, Newark, New Jersey, USA
| | - Jyothsna Chitturi
- Department of Radiology, Rutgers Biomedical and Health Sciences–New Jersey Medical School, Newark, New Jersey, USA
| | - Peter Herman
- Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Stella Elkabes
- Department of Neurosurgery, Rutgers Biomedical and Health Sciences–New Jersey Medical School, Newark, New Jersey, USA
| | - Robert Heary
- Hackensack Meridian School of Medicine, Mountainside Medical Center, Montclair, New Jersey, USA
| | - Fahmeed Hyder
- Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Sridhar S. Kannurpatti
- Department of Radiology, Rutgers Biomedical and Health Sciences–New Jersey Medical School, Newark, New Jersey, USA.,Address correspondence to: Sridhar S. Kannurpatti, PhD, Department of Radiology, RUTGERS–New Jersey Medical School, MSB, F-506, 185 South Orange Avenue, Newark, NJ 07103, USA.
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3
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Vianna-Barbosa R, Bahia CP, Sanabio A, de Freitas GPA, Madeiro da Costa RF, Garcez PP, Miranda K, Lent R, Tovar-Moll F. Myelination of Callosal Axons Is Hampered by Early and Late Forelimb Amputation in Rats. Cereb Cortex Commun 2020; 2:tgaa090. [PMID: 34296146 PMCID: PMC8152840 DOI: 10.1093/texcom/tgaa090] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 11/17/2020] [Accepted: 11/22/2020] [Indexed: 11/14/2022] Open
Abstract
Deafferentation is an important determinant of plastic changes in the CNS, which consists of a loss of inputs from the body periphery or from the CNS itself. Although cortical reorganization has been well documented, white matter plasticity was less explored. Our goal was to investigate microstructural interhemispheric connectivity changes in early and late amputated rats. For that purpose, we employed diffusion-weighted magnetic resonance imaging, as well as Western blotting, immunohistochemistry, and electron microscopy of sections of the white matter tracts to analyze the microstructural changes in the corticospinal tract and in the corpus callosum (CC) sector that contains somatosensory fibers integrating cortical areas representing the forelimbs and compare differences in rats undergoing forelimb amputation as neonates, with those amputated as adults. Results showed that early amputation induced decreased fractional anisotropy values and reduction of total myelin amount in the cerebral peduncle contralateral to the amputation. Both early and late forelimb amputations induced decreased myelination of callosal fibers. While early amputation affected myelination of thinner axons, late amputation disrupted axons of all calibers. Since the CC provides a modulation of inhibition and excitation between the hemispheres, we suggest that the demyelination observed among callosal fibers may misbalance this modulation.
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Affiliation(s)
- Rodrigo Vianna-Barbosa
- Post-Graduate Program in Morphological Sciences, Institute of Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro CEP 21941-902, Brazil.,National Center of Structural Biology and Bioimaging, Federal University of Rio de Janeiro, Rio de Janeiro CEP 21941-902, Brazil
| | - Carlomagno P Bahia
- Institute of Health Sciences, Federal University of Pará, Pará CEP 66035-160, Brazil
| | - Alexandre Sanabio
- Post-Graduate Program in Morphological Sciences, Institute of Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro CEP 21941-902, Brazil
| | - Gabriella P A de Freitas
- Post-Graduate Program in Morphological Sciences, Institute of Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro CEP 21941-902, Brazil
| | | | - Patricia P Garcez
- Post-Graduate Program in Morphological Sciences, Institute of Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro CEP 21941-902, Brazil
| | - Kildare Miranda
- National Center of Structural Biology and Bioimaging, Federal University of Rio de Janeiro, Rio de Janeiro CEP 21941-902, Brazil.,Institute of Biophysics, Federal University of Rio de Janeiro, Rio de Janeiro CEP 21941-902, Brazil
| | - Roberto Lent
- Post-Graduate Program in Morphological Sciences, Institute of Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro CEP 21941-902, Brazil.,D'Or Institute of Research and Education (IDOR), Rio de Janeiro, CEP 22281-100, Brazil
| | - Fernanda Tovar-Moll
- Post-Graduate Program in Morphological Sciences, Institute of Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro CEP 21941-902, Brazil.,National Center of Structural Biology and Bioimaging, Federal University of Rio de Janeiro, Rio de Janeiro CEP 21941-902, Brazil.,D'Or Institute of Research and Education (IDOR), Rio de Janeiro, CEP 22281-100, Brazil
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McCann MM, Fisher KM, Ahloy-Dallaire J, Darian-Smith C. Somatosensory corticospinal tract axons sprout within the cervical cord following a dorsal root/dorsal column spinal injury in the rat. J Comp Neurol 2020; 528:1293-1306. [PMID: 31769033 PMCID: PMC7102935 DOI: 10.1002/cne.24826] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 11/18/2019] [Accepted: 11/20/2019] [Indexed: 12/19/2022]
Abstract
The corticospinal tract (CST) is the major descending pathway controlling voluntary hand function in primates, and though less dominant, it mediates voluntary paw movements in rats. As with primates, the CST in rats originates from multiple (albeit fewer) cortical sites, and functionally different motor and somatosensory subcomponents terminate in different regions of the spinal gray matter. We recently reported in monkeys that following a combined cervical dorsal root/dorsal column lesion (DRL/DCL), both motor and S1 CSTs sprout well beyond their normal terminal range. The S1 CST sprouting response is particularly dramatic, indicating an important, if poorly understood, somatosensory role in the recovery process. As rats are used extensively to model spinal cord injury, we asked if the S1 CST response is conserved in rodents. Rats were divided into sham controls, and two groups surviving post-lesion for ~6 and 10 weeks. A DRL/DCL was made to partially deafferent one paw. Behavioral testing showed a post-lesion deficit and recovery over several weeks. Three weeks prior to ending the experiment, S1 cortex was mapped electrophysiologically, for tracer injection placement to determine S1 CST termination patterns within the cord. Synaptogenesis was also assessed for labeled S1 CST terminals within the dorsal horn. Our findings show that the affected S1 CST sprouts well beyond its normal range in response to a DRL/DCL, much as it does in macaque monkeys. This, along with evidence for increased synaptogenesis post-lesion, indicates that CST terminal sprouting following a central sensory lesion, is a robust and conserved response.
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Affiliation(s)
- Margaret M. McCann
- Department of Comparative Medicine, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA94305-5342
- Margaret M. McCann, Creighton University, Department of Biomedical Sciences, 2500 California Plaza, Criss II, Omaha NE 68178
| | - Karen M. Fisher
- Department of Comparative Medicine, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA94305-5342
| | - Jamie Ahloy-Dallaire
- Department of Comparative Medicine, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA94305-5342
- Département des sciences animales, Université Laval, 2425 rue de l’Agriculture, Québec, Québec, Canada G1V 0A6
| | - Corinna Darian-Smith
- Department of Comparative Medicine, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA94305-5342
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5
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Slow-Wave Activity in the S1HL Cortex Is Contributed by Different Layer-Specific Field Potential Sources during Development. J Neurosci 2019; 39:8900-8915. [PMID: 31548234 PMCID: PMC6832678 DOI: 10.1523/jneurosci.1212-19.2019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 08/06/2019] [Accepted: 08/27/2019] [Indexed: 01/12/2023] Open
Abstract
Spontaneous correlated activity in cortical columns is critical for postnatal circuit refinement. We used spatial discrimination techniques to explore the late maturation of synaptic pathways through the laminar distribution of the field potential (FP) generators underlying spontaneous and evoked activities of the S1HL cortex in juvenile (P14-P16) and adult anesthetized rats. Juveniles exhibit an intermittent FP pattern resembling Up/Down states in adults, but with much reduced power and different laminar distribution. Whereas FPs in active periods are dominated by a layer VI generator in juveniles, in adults a developing multipart generator takes over, displaying current sinks in middle layers (III-V). The blockade of excitatory transmission in upper and middle layers of adults recovered the juvenile-like FP profiles. In addition to the layer VI generator, a gamma-specific generator in supragranular layers was the same in both age groups. While searching for dynamical coupling among generators in juveniles we found significant cross-correlation in ∼one-half of the tested pairs, whereas excessive coherence hindered their efficient separation in adults. Also, potentials evoked by tactile and electrical stimuli showed different short-latency dipoles between the two age groups, and the juveniles lacked the characteristic long latency UP state currents in middle layers. In addition, the mean firing rate of neurons was lower in juveniles. Thus, cortical FPs originate from different intra-columnar segments as they become active postnatally. We suggest that although some cortical segments are active early postnatally, a functional sensory-motor control relies on a delayed maturation and network integration of synaptic connections in middle layers.SIGNIFICANCE STATEMENT Early postnatal activity in the rodent cortex is mostly endogenous, whereas it becomes driven by peripheral input at later stages. The precise schedule for the maturation of synaptic pathways is largely unknown. We explored this in the somatosensory hindlimb cortex at an age when animals begin to use their limbs by uncovering the laminar distribution of the field potential generators underlying the dominant delta waves in juveniles and adults. Our results suggest that field potentials are mostly generated by a pathway in deep layers, whereas other pathways mature later in middle layers and take over in adults. We suggest that a functional sensory-motor control relies on a delayed maturation and network integration of synaptic connections in middle layers.
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Jutzeler CR, Streijger F, Aguilar J, Shortt K, Manouchehri N, Okon E, Hupp M, Curt A, Kwon BK, Kramer JLK. Sensorimotor plasticity after spinal cord injury: a longitudinal and translational study. Ann Clin Transl Neurol 2018; 6:68-82. [PMID: 30656185 PMCID: PMC6331953 DOI: 10.1002/acn3.679] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 09/12/2018] [Accepted: 10/03/2018] [Indexed: 11/06/2022] Open
Abstract
Objective The objective was to track and compare the progression of neuroplastic changes in a large animal model and humans with spinal cord injury. Methods A total of 37 individuals with acute traumatic spinal cord injury were followed over time (1, 3, 6, and 12 months post-injury) with repeated neurophysiological assessments. Somatosensory and motor evoked potentials were recorded in the upper extremities above the level of injury. In a reverse-translational approach, similar neurophysiological techniques were examined in a porcine model of thoracic spinal cord injury. Twelve Yucatan mini-pigs underwent a contusive spinal cord injury at T10 and tracked with somatosensory and motor evoked potentials assessments in the fore- and hind limbs pre- (baseline, post-laminectomy) and post-injury (10 min, 3 h, 12 weeks). Results In both humans and pigs, the sensory responses in the cranial coordinates of upper extremities/forelimbs progressively increased from immediately post-injury to later time points. Motor responses in the forelimbs increased immediately after experimental injury in pigs, remaining elevated at 12 weeks. In humans, motor evoked potentials were significantly higher at 1-month (and remained so at 1 year) compared to normative values. Conclusions Despite notable differences between experimental models and the human condition, the brain's response to spinal cord injury is remarkably similar between humans and pigs. Our findings further underscore the utility of this large animal model in translational spinal cord injury research.
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Affiliation(s)
- Catherine R Jutzeler
- Spinal Cord Injury Center University Hospital Balgrist University of Zurich Zurich Switzerland.,ICORD University of British Columbia Vancouver British Columbia Canada.,School of Kinesiology University of British Columbia Vancouver British Columbia Canada
| | - Femke Streijger
- ICORD University of British Columbia Vancouver British Columbia Canada
| | - Juan Aguilar
- Experimental Neurophysiology Group Hospital Nacional de Parapléjicos SESCAM Toledo Spain
| | - Katelyn Shortt
- ICORD University of British Columbia Vancouver British Columbia Canada
| | - Neda Manouchehri
- Spinal Cord Injury Center University Hospital Balgrist University of Zurich Zurich Switzerland
| | - Elena Okon
- Spinal Cord Injury Center University Hospital Balgrist University of Zurich Zurich Switzerland
| | - Markus Hupp
- Spinal Cord Injury Center University Hospital Balgrist University of Zurich Zurich Switzerland
| | - Armin Curt
- Spinal Cord Injury Center University Hospital Balgrist University of Zurich Zurich Switzerland.,European Multi-Centre Study about Spinal Cord Injury (EMSCI) Study Group University Hospital Balgrist University of Zurich Zurich 8008 Switzerland
| | - Brian K Kwon
- ICORD University of British Columbia Vancouver British Columbia Canada
| | - John L K Kramer
- ICORD University of British Columbia Vancouver British Columbia Canada.,School of Kinesiology University of British Columbia Vancouver British Columbia Canada
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7
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Balaram P, Hackett TA, Polley DB. Synergistic Transcriptional Changes in AMPA and GABA A Receptor Genes Support Compensatory Plasticity Following Unilateral Hearing Loss. Neuroscience 2018; 407:108-119. [PMID: 30176318 DOI: 10.1016/j.neuroscience.2018.08.023] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 08/02/2018] [Accepted: 08/22/2018] [Indexed: 01/11/2023]
Abstract
Debilitating perceptual disorders including tinnitus, hyperacusis, phantom limb pain and visual release hallucinations may reflect aberrant patterns of neural activity in central sensory pathways following a loss of peripheral sensory input. Here, we explore short- and long-term changes in gene expression that may contribute to hyperexcitability following a sudden, profound loss of auditory input from one ear. We used fluorescence in situ hybridization to quantify mRNA levels for genes encoding AMPA and GABAA receptor subunits (Gria2 and Gabra1, respectively) in single neurons from the inferior colliculus (IC) and auditory cortex (ACtx). Thirty days after unilateral hearing loss, Gria2 levels were significantly increased while Gabra1 levels were significantly decreased. Transcriptional rebalancing was more pronounced in ACtx than IC and bore no obvious relationship to the degree of hearing loss. By contrast to the opposing, synergistic shifts in Gria2 and Gabra1 observed 30 days after hearing loss, we found that transcription levels for both genes were equivalently reduced after 5 days of hearing loss, producing no net change in the excitatory/inhibitory transcriptional balance. Opposing transcriptional shifts in AMPA and GABA receptor genes that emerge several weeks after a peripheral insult could promote both sensitization and disinhibition to support a homeostatic recovery of neural activity following auditory deprivation. Imprecise transcriptional changes could also drive the system toward perceptual hypersensitivity, degraded temporal processing and the irrepressible perception of non-existent environmental stimuli, a trio of perceptual impairments that often accompany chronic sensory deprivation.
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Affiliation(s)
- P Balaram
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear Infirmary, Boston MA 02114, USA; Dept. of Otolaryngology, Harvard Medical School, Boston MA 02114, USA
| | - T A Hackett
- Dept. of Hearing and Speech Sciences, Vanderbilt Bill Wilkerson Center for Otolaryngology and Communication Sciences, Vanderbilt University Medical Center, Nashville TN 37232 USA
| | - D B Polley
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear Infirmary, Boston MA 02114, USA; Dept. of Otolaryngology, Harvard Medical School, Boston MA 02114, USA.
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Manohar A, Foffani G, Ganzer PD, Bethea JR, Moxon KA. Cortex-dependent recovery of unassisted hindlimb locomotion after complete spinal cord injury in adult rats. eLife 2017; 6. [PMID: 28661400 PMCID: PMC5499944 DOI: 10.7554/elife.23532] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2016] [Accepted: 06/22/2017] [Indexed: 12/29/2022] Open
Abstract
After paralyzing spinal cord injury the adult nervous system has little ability to ‘heal’ spinal connections, and it is assumed to be unable to develop extra-spinal recovery strategies to bypass the lesion. We challenge this assumption, showing that completely spinalized adult rats can recover unassisted hindlimb weight support and locomotion without explicit spinal transmission of motor commands through the lesion. This is achieved with combinations of pharmacological and physical therapies that maximize cortical reorganization, inducing an expansion of trunk motor cortex and forepaw sensory cortex into the deafferented hindlimb cortex, associated with sprouting of corticospinal axons. Lesioning the reorganized cortex reverses the recovery. Adult rats can thus develop a novel cortical sensorimotor circuit that bypasses the lesion, probably through biomechanical coupling, to partly recover unassisted hindlimb locomotion after complete spinal cord injury. DOI:http://dx.doi.org/10.7554/eLife.23532.001
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Affiliation(s)
- Anitha Manohar
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, United States
| | - Guglielmo Foffani
- CINAC, Hospital Universitario HM Puerta del Sur, Universidad CEU-San Pablo, Madrid, Spain.,Hospital Nacional de Parapléjicos, Servicio de Salud de Castilla-La Mancha, Toledo, Spain
| | - Patrick D Ganzer
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, United States
| | - John R Bethea
- Department of Biology, Drexel University, Philadelphia, United States
| | - Karen A Moxon
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, United States.,Department of Biomedical Engineering, University of California, Davis, United States
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