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Bartmeyer PM, Biscola NP, Havton LA. Nonbinary 2D Distribution Tool Maps Autonomic Nerve Fiber Clustering in Lumbosacral Ventral Roots of Rhesus Macaques. eNeuro 2024; 11:ENEURO.0009-23.2024. [PMID: 38548331 PMCID: PMC11015947 DOI: 10.1523/eneuro.0009-23.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 12/13/2023] [Accepted: 02/05/2024] [Indexed: 04/14/2024] Open
Abstract
Neuromodulation of the peripheral nervous system (PNS) by electrical stimulation may augment autonomic function after injury or in neurodegenerative disorders. Nerve fiber size, myelination, and distance between individual fibers and the stimulation electrode may influence response thresholds to electrical stimulation. However, information on the spatial distribution of nerve fibers within the PNS is sparse. We developed a new two-dimensional (2D) morphological mapping tool to assess spatial heterogeneity and clustering of nerve fibers. The L6-S3 ventral roots (VRs) in rhesus macaques were used as a model system to map preganglionic parasympathetic, γ-motor, and α-motor fibers. Random and ground truth distributions of nerve fiber centroids were determined for each VR by light microscopy. The proposed tool allows for nonbinary determinations of fiber heterogeneity by defining the minimum distance between nerve fibers for cluster inclusion and comparisons with random fiber distributions for each VR. There was extensive variability in the relative composition of nerve fiber types and degree of 2D fiber heterogeneity between different L6-S3 VR levels within and across different animals. There was a positive correlation between the proportion of autonomic fibers and the degree of nerve fiber clustering. Nerve fiber cluster heterogeneity between VRs may contribute to varied functional outcomes from neuromodulation.
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Affiliation(s)
- Petra M Bartmeyer
- Departments of Neurology, Icahn School of Medicine at Mount Sinai, New York, New York 10029
| | - Natalia P Biscola
- Departments of Neurology, Icahn School of Medicine at Mount Sinai, New York, New York 10029
| | - Leif A Havton
- Departments of Neurology, Icahn School of Medicine at Mount Sinai, New York, New York 10029
- Neuroscience, Icahn School of Medicine at Mount Sinai, New York, New York 10029
- James J. Peters Veterans Affairs Medical Center, Bronx, New York 10468
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Bennet BM, Pardo ID, Assaf BT, Buza E, Cramer S, Crawford LK, Engelhardt JA, Grubor B, Morrison JP, Osborne TS, Sharma AK, Bolon B. Scientific and Regulatory Policy Committee Points to Consider: Sampling, Processing, Evaluation, Interpretation, and Reporting of Test Article-Related Ganglion Pathology for Nonclinical Toxicity Studies. Toxicol Pathol 2023; 51:176-204. [PMID: 37489508 DOI: 10.1177/01926233231179707] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/26/2023]
Abstract
Certain biopharmaceutical products consistently affect dorsal root ganglia, trigeminal ganglia, and/or autonomic ganglia. Product classes targeting ganglia include antineoplastic chemotherapeutics, adeno-associated virus-based gene therapies, antisense oligonucleotides, and anti-nerve growth factor agents. This article outlines "points to consider" for sample collection, processing, evaluation, interpretation, and reporting of ganglion findings; these points are consistent with published best practices for peripheral nervous system evaluation in nonclinical toxicity studies. Ganglion findings often occur as a combination of neuronal injury (e.g., degeneration, necrosis, and/or loss) and/or glial effects (e.g., increased satellite glial cell cellularity) with leukocyte accumulation (e.g., mononuclear cell infiltration or inflammation). Nerve fiber degeneration and/or glial reactions may be seen in nerves, dorsal spinal nerve roots, spinal cord, and occasionally brainstem. Interpretation of test article (TA)-associated effects may be confounded by incidental background changes or experimental procedure-related changes and limited historical control data. Reports should describe findings at these sites, any TA relationship, and the criteria used for assigning severity grades. Contextualizing adversity of ganglia findings can require a weight-of-evidence approach because morphologic changes of variable severity occur in ganglia but often are not accompanied by observable overt in-life functional alterations detectable by conventional behavioral and neurological testing techniques.
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Affiliation(s)
| | | | | | - Elizabeth Buza
- University of Pennsylvania, Gene Therapy Program, Philadelphia, Pennsylvania, USA
| | | | - LaTasha K Crawford
- University of Wisconsin-Madison, School of Veterinary Medicine, Madison, Wisconsin, USA
| | | | | | - James P Morrison
- Charles River Laboratories, Inc., Shrewsbury, Massachusetts, USA
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Bartmeyer PM, Biscola NP, Havton LA. A shape-adjusted ellipse approach corrects for varied axonal dispersion angles and myelination in primate nerve roots. Sci Rep 2021; 11:3150. [PMID: 33542368 PMCID: PMC7862494 DOI: 10.1038/s41598-021-82575-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Accepted: 01/21/2021] [Indexed: 11/12/2022] Open
Abstract
Segmentation of axons in light and electron micrographs allows for quantitative high-resolution analysis of nervous tissues, but varied axonal dispersion angles result in over-estimates of fiber sizes. To overcome this technical challenge, we developed a novel shape-adjusted ellipse (SAE) determination of axonal size and myelination as an all-inclusive and non-biased tool to correct for oblique nerve fiber presentations. Our new resource was validated by light and electron microscopy against traditional methods of determining nerve fiber size and myelination in rhesus macaques as a model system. We performed detailed segmental mapping and characterized the morphological signatures of autonomic and motor fibers in primate lumbosacral ventral roots (VRs). An en bloc inter-subject variability for the preganglionic parasympathetic fibers within the L7-S2 VRs was determined. The SAE approach allows for morphological ground truth data collection and assignment of individual axons to functional phenotypes with direct implications for fiber mapping and neuromodulation studies.
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Affiliation(s)
- Petra M Bartmeyer
- Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.,School of Electrical and Computer Engineering at University of Campinas, Campinas, SP, Brazil
| | - Natalia P Biscola
- Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.,Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Leif A Havton
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA. .,Departments of Neurology and Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA. .,Departments of Neurology and Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA. .,Neurology Service and RR&D National Center for the Medical Consequences of Spinal Cord Injury, James J. Peters Veterans Administration Medical Center, Bronx, NY, USA.
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Toossi A, Everaert DG, Perlmutter SI, Mushahwar VK. Functional organization of motor networks in the lumbosacral spinal cord of non-human primates. Sci Rep 2019; 9:13539. [PMID: 31537819 PMCID: PMC6753145 DOI: 10.1038/s41598-019-49328-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Accepted: 08/24/2019] [Indexed: 12/17/2022] Open
Abstract
Implantable spinal-cord-neuroprostheses aiming to restore standing and walking after paralysis have been extensively studied in animal models (mainly cats) and have shown promising outcomes. This study aimed to take a critical step along the clinical translation path of these neuroprostheses, and investigated the organization of the neural networks targeted by these implants in a non-human primate. This was accomplished by advancing a microelectrode into various locations of the lumbar enlargement of the spinal cord, targeting the ventral horn of the gray matter. Microstimulation in these locations produced a variety of functional movements in the hindlimb. The resulting functional map of the spinal cord in monkeys was found to have a similar overall organization along the length of the spinal cord to that in cats. This suggests that the human spinal cord may also be organized similarly. The obtained spinal cord maps in monkeys provide important knowledge that will guide the very first testing of these implants in humans.
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Affiliation(s)
- Amirali Toossi
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada.,Sensory Motor Adaptive Rehabilitation Technology (SMART) Network, University of Alberta, Edmonton, Alberta, Canada
| | - Dirk G Everaert
- Division of Physical Medicine and Rehabilitation, Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada.,Sensory Motor Adaptive Rehabilitation Technology (SMART) Network, University of Alberta, Edmonton, Alberta, Canada
| | - Steve I Perlmutter
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington, USA.,Washington National Primate Research Centre, Seattle, Washington, USA.,Sensory Motor Adaptive Rehabilitation Technology (SMART) Network, University of Alberta, Edmonton, Alberta, Canada.,Center for Sensorimotor Neural Engineering, Seattle, Washington, USA
| | - Vivian K Mushahwar
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada. .,Division of Physical Medicine and Rehabilitation, Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada. .,Sensory Motor Adaptive Rehabilitation Technology (SMART) Network, University of Alberta, Edmonton, Alberta, Canada.
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Noninvasive spinal neuromodulation to map and augment lower urinary tract function in rhesus macaques. Exp Neurol 2019; 322:113033. [PMID: 31400304 DOI: 10.1016/j.expneurol.2019.113033] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 07/15/2019] [Accepted: 08/06/2019] [Indexed: 12/25/2022]
Abstract
Dysfunction of the lower urinary tract (LUT) is prevalent in neurological disorders, including multiple sclerosis, stroke, spinal cord injury and neurodegenerative conditions. Common symptoms include urgency, incontinence, and urinary retention. Recent advances in neuromodulation have resulted in improved treatments for overactive bladder symptoms of urgency, frequency, and nocturia. However, there are presently no treatments available for the induction of voiding to overcome urinary retention. We demonstrate that transcutaneous spinal cord stimulation (TSCS), a non-invasive intervention, applied over the thoracolumbar spine in neurologically intact rhesus macaques can activate the LUT, including activation of the bladder detrusor muscle, the urethral sphincter and pelvic floor muscles. Urodynamic studies show improved voiding efficiency and decreased post-voiding residual volumes in the bladder, while maintaining coordinated activity in the detrusor and sphincter with physiologic detrusor peak pressure, contraction duration, and urine flow rate remaining unchanged. We conclude that TSCS may represent a novel approach to activate the LUT and enable voiding in select neurological conditions.
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Chang HH, Lee U, Vu T, Pikov V, Nieto JH, Christe KL, Havton LA. EMG characteristics of the external anal sphincter guarding reflex and effects of a unilateral ventral root avulsion injury in rhesus macaques ( Macaca mulatta). J Neurophysiol 2018; 120:2710-2718. [PMID: 30089020 PMCID: PMC6337026 DOI: 10.1152/jn.00435.2017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 08/06/2018] [Accepted: 08/06/2018] [Indexed: 11/22/2022] Open
Abstract
The external anal sphincter (EAS) is important for the maintenance of bowel continence and may be compromised by a variety of neuropathic conditions. However, large animal models for the study of EAS functions have been sparse. The EAS guarding reflex was examined by electromyography (EMG) in neurologically intact rhesus macaques ( n = 6) and at 4-6 wk after a unilateral EAS denervation from an L6-S3 ventral root avulsion (VRA) injury ( n = 6). Baseline EAS EMG recordings were quiescent in all subjects, and evoked responses showed an initial large-amplitude EMG activity, which gradually returned to baseline within 1-2 min. At 4-6 wk postoperatively, the EAS guarding reflex showed a significantly reduced EMG response duration of 47 ± 15 s and area under the curve (AUC) of 0.198 ± 0.097 mV·s compared with the corresponding evoked EAS EMG duration of 102 ± 19 s and AUC of 0.803 ± 0.225 mV·s ( P < 0.05) in the control group. Detailed time- and frequency-domain analysis of the evoked EAS EMG responses for the first 40 s showed no difference between groups for the maximum amplitude but a significant decrease for the mean amplitude across the study period and an early AUC reduction for the first 10 s in the VRA injury group. Time-frequency analysis and power spectrum plots indicated decreased intensity and a narrower midrange of frequencies in the VRA injury group. We conclude that the EAS guarding reflex in rhesus macaques shows characteristic EMG features in control subjects and signs of partial target denervation after a unilateral L6-S3 VRA injury. NEW & NOTEWORTHY The external anal sphincter guarding reflex showed initial large-amplitude peaks and a gradual return to a quiescent baseline after a rectal probe stimulus in rhesus macaques. At 4-6 wk after a unilateral ventral root avulsion (VRA) injury, the electromyography duration, mean amplitude, and area under the curve measurements were decreased. Time-frequency analysis and power spectrum plots indicated decreased intensity and a narrowed midrange of frequencies in the VRA injury cohort.
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Affiliation(s)
- Huiyi H Chang
- Department of Urology and Reeve-Irvine Research Center, University of California , Irvine, California
| | - Una Lee
- Section of Urology, Virginia Mason Medical Center , Seattle, Washington
| | - Timothy Vu
- Department of Biochemistry and Molecular Biology, University of Chicago , Chicago, Illinois
| | | | - Jaime H Nieto
- Department of Neurology, David Geffen School of Medicine, University of California , Los Angeles, California
| | - Kari L Christe
- California National Primate Research Center, University of California , Davis, California
| | - Leif A Havton
- Department of Neurology, David Geffen School of Medicine, University of California , Los Angeles, California
- Department of Neurobiology, David Geffen School of Medicine, University of Los Angeles, California
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Gad PN, Kokikian N, Christe KL, Edgerton VR, Havton LA. Noninvasive neurophysiological mapping of the lower urinary tract in adult and aging rhesus macaques. J Neurophysiol 2018; 119:1521-1527. [PMID: 29361664 DOI: 10.1152/jn.00840.2017] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The lower urinary tract (LUT) may be activated by spinal cord stimulation, but the physiological mapping characteristics of LUT activation with noninvasive transcutaneous spinal cord stimulation (TSCS) are not known. The effects of aging on the contractile properties of the detrusor are also not well understood. Therefore, TSCS was applied over the T10/T11 to L6/L7 spinous processes in adult ( n = 6) and aged ( n = 9) female rhesus macaques. A combination of urodynamic studies and electromyography recordings of the external urethral sphincter (EUS), external anal sphincter (EAS), and pelvic floor muscles was performed. Distinct functional maps were demonstrated for TSCS-evoked detrusor and urethral pressures and for the activation of the EUS, EAS, and pelvic floor muscles. The magnitude of responses for each peripheral target organ was dependent on TSCS location and strength. The strongest detrusor contraction was observed with TSCS at the L1/L2 site in adults and the L3/L4 site in aged subjects. TSCS-evoked bladder pressure at the L1/L2 site was significantly higher for the adults compared with the aged subjects ( P < 0.05). Cumulative normalized TSCS-evoked pressures, calculated for five consecutive sites between the T11/T12 and L3/L4 levels, were significantly lower for aged compared with adult subjects ( P < 0.05). The aged animals also showed a caudal shift for the TSCS site that generated the strongest detrusor contraction. We conclude that natural aging in rhesus macaques is associated with decreased detrusor contractility, a finding of significant translational research relevance as detrusor underactivity is a common occurrence with aging in humans. NEW & NOTEWORTHY Transcutaneous spinal cord stimulation (TSCS) was used to map lower urinary tract function in adult and aged rhesus macaques. Aging was associated with decreased peak pressure responses to TSCS, reduced cumulative normalized evoked bladder pressure responses, and a caudal shift for the site generating the strongest TSCS-induced detrusor contraction. We demonstrate the utility of TSCS as a new diagnostic tool for detrusor contractility assessments and conclude that aging is associated with decreased detrusor contractility in primates.
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Affiliation(s)
- Parag N Gad
- Department of Integrative Biology and Physiology, University of California , Los Angeles, California
| | - Nelly Kokikian
- Department of Integrative Biology and Physiology, University of California , Los Angeles, California
| | - Kari L Christe
- California National Primate Research Center, University of California , Davis, California
| | - V Reggie Edgerton
- Department of Integrative Biology and Physiology, University of California , Los Angeles, California.,Department of Neurobiology, David Geffen School of Medicine at University of California , Los Angeles, California.,Department of Neurosurgery, David Geffen School of Medicine at University of California , Los Angeles, California.,Brain Research Institute, University of California , Los Angeles, California.,Institut Guttmann, Hospital de Neurorehabilitació, Universitat Autònoma de Barcelona, Badalona, Spain.,Centre for Neuroscience and Regenerative Medicine, University of Technology , Sydney , Australia
| | - Leif A Havton
- Department of Neurobiology, David Geffen School of Medicine at University of California , Los Angeles, California.,Department of Neurology, David Geffen School of Medicine at University of California , Los Angeles, California
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