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Krotov V, Belan P, Voitenko N. Approach for Electrophysiological Studies of Spinal Lamina X Neurons. Bio Protoc 2024; 14:e5035. [PMID: 39100598 PMCID: PMC11292132 DOI: 10.21769/bioprotoc.5035] [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: 04/15/2024] [Revised: 06/15/2024] [Accepted: 06/16/2024] [Indexed: 08/06/2024] Open
Abstract
Despite playing diverse physiological roles, the area surrounding the central canal, lamina X, remains one of the least studied spinal cord regions. Technical challenges and limitations of the commonly used experimental approaches are the main difficulties that hamper lamina X research. In the current protocol, we describe a reliable method for functional investigation of lamina X neurons that requires neither time-consuming slicing nor sophisticated in vivo experiments. Our approach relies on ex vivo hemisected spinal cord preparation that preserves the rostrocaudal and mediolateral spinal architecture as well as the dorsal roots, and infrared LED oblique illumination for visually guided patch clamp in thick blocks of tissue. When coupled with electric stimulation of the spared dorsal roots, electrophysiological recordings provide information on primary afferent inputs to lamina X neurons from myelinated and non-myelinated fibers and allow estimating primary afferent-driven presynaptic inhibition. Overall, we describe a simple, time-efficient, inexpensive, and versatile approach for lamina X research. Key features • Quick and easy preparation procedure that grants access to lamina X neurons without spinal cord slicing • Preserved rostrocaudal and mediolateral connectivity and preserved primary afferent supply • Ability to perform electrophysiological recordings in combination with dorsal root stimulations allowing to study afferent inputs and presynaptic inhibition of lamina X neurons.
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Affiliation(s)
- Volodymyr Krotov
- Department of Molecular Biophysics, Bogomoletz Institute of Physiology, Kyiv, Ukraine
| | - Pavel Belan
- Department of Molecular Biophysics, Bogomoletz Institute of Physiology, Kyiv, Ukraine
- Department of Biomedicine and Neuroscience, Kyiv Academic University, Kyiv, Ukraine
| | - Nana Voitenko
- Department of Biomedicine and Neuroscience, Kyiv Academic University, Kyiv, Ukraine
- Dobrobut Academy Medical School, Kyiv, Ukraine
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Safronov BV, Szucs P. Novel aspects of signal processing in lamina I. Neuropharmacology 2024; 247:109858. [PMID: 38286189 DOI: 10.1016/j.neuropharm.2024.109858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Revised: 01/12/2024] [Accepted: 01/25/2024] [Indexed: 01/31/2024]
Abstract
The most superficial layer of the spinal dorsal horn, lamina I, is a key element of the nociceptive processing system. It contains different types of projection neurons (PNs) and local-circuit neurons (LCNs) whose functional roles in the signal processing are poorly understood. This article reviews recent progress in elucidating novel anatomical features and physiological properties of lamina I PNs and LCNs revealed by whole-cell recordings in ex vivo spinal cord. This article is part of the Special Issue on "Ukrainian Neuroscience".
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Affiliation(s)
- Boris V Safronov
- Neuronal Networks Group, Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.
| | - Peter Szucs
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary; HUN-REN-DE Neuroscience Research Group, Debrecen, Hungary
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3
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Krotov V, Agashkov K, Romanenko S, Halaidych O, Andrianov Y, Safronov BV, Belan P, Voitenko N. Elucidating afferent-driven presynaptic inhibition of primary afferent input to spinal laminae I and X. Front Cell Neurosci 2023; 16:1029799. [PMID: 36713779 PMCID: PMC9874151 DOI: 10.3389/fncel.2022.1029799] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 12/14/2022] [Indexed: 01/13/2023] Open
Abstract
Although spinal processing of sensory information greatly relies on afferent-driven (AD) presynaptic inhibition (PI), our knowledge about how it shapes peripheral input to different types of nociceptive neurons remains insufficient. Here we examined the AD-PI of primary afferent input to spinal neurons in the marginal layer, lamina I, and the layer surrounding the central canal, lamina X; two nociceptive-processing regions with similar patterns of direct supply by Aδ- and C-afferents. Unmyelinated C-fibers were selectively activated by electrical stimuli of negative polarity that induced an anodal block of myelinated Aβ/δ-fibers. Combining this approach with the patch-clamp recording in an ex vivo spinal cord preparation, we found that attenuation of the AD-PI by the anodal block of Aβ/δ-fibers resulted in the appearance of new mono- and polysynaptic C-fiber-mediated excitatory postsynaptic current (EPSC) components. Such homosegmental Aβ/δ-AD-PI affected neurons in the segment of the dorsal root entrance as well as in the adjacent rostral segment. In their turn, C-fibers from the L5 dorsal root induced heterosegmental AD-PI of the inputs from the L4 Aδ- and C-afferents to the neurons in the L4 segment. The heterosegmental C-AD-PI was reciprocal since the L4 C-afferents inhibited the L5 Aδ- and C-fiber inputs, as well as some direct L5 Aβ-fiber inputs. Moreover, the C-AD-PI was found to control the spike discharge in spinal neurons. Given that the homosegmental Aβ/δ-AD-PI and heterosegmental C-AD-PI affected a substantial percentage of lamina I and X neurons, we suggest that these basic mechanisms are important for shaping primary afferent input to the neurons in the spinal nociceptive-processing network.
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Affiliation(s)
- Volodymyr Krotov
- Department of Sensory Signaling, Bogomoletz Institute of Physiology, Kyiv, Ukraine,Department of Molecular Biophysics, Bogomoletz Institute of Physiology, Kyiv, Ukraine,*Correspondence: Volodymyr Krotov,
| | - Kirill Agashkov
- Department of Sensory Signaling, Bogomoletz Institute of Physiology, Kyiv, Ukraine
| | - Sergii Romanenko
- Department of Sensory Signaling, Bogomoletz Institute of Physiology, Kyiv, Ukraine
| | - Oleh Halaidych
- Department of Sensory Signaling, Bogomoletz Institute of Physiology, Kyiv, Ukraine
| | - Yaroslav Andrianov
- Department of Sensory Signaling, Bogomoletz Institute of Physiology, Kyiv, Ukraine
| | - Boris V. Safronov
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal,Neuronal Networks Group, Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
| | - Pavel Belan
- Department of Molecular Biophysics, Bogomoletz Institute of Physiology, Kyiv, Ukraine,Department of Biomedicine and Neuroscience, Kyiv Academic University, Kyiv, Ukraine
| | - Nana Voitenko
- Department of Sensory Signaling, Bogomoletz Institute of Physiology, Kyiv, Ukraine,Department of Biomedicine and Neuroscience, Kyiv Academic University, Kyiv, Ukraine,Dobrobut Academy Medical School, Kyiv, Ukraine
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4
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Tadokoro T, Bravo-Hernandez M, Agashkov K, Kobayashi Y, Platoshyn O, Navarro M, Marsala S, Miyanohara A, Yoshizumi T, Shigyo M, Krotov V, Juhas S, Juhasova J, Nguyen D, Kupcova Skalnikova H, Motlik J, Studenovska H, Proks V, Reddy R, Driscoll SP, Glenn TD, Kemthong T, Malaivijitnond S, Tomori Z, Vanicky I, Kakinohana M, Pfaff SL, Ciacci J, Belan P, Marsala M. Precision spinal gene delivery-induced functional switch in nociceptive neurons reverses neuropathic pain. Mol Ther 2022; 30:2722-2745. [PMID: 35524407 PMCID: PMC9372322 DOI: 10.1016/j.ymthe.2022.04.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 03/31/2022] [Accepted: 04/29/2022] [Indexed: 11/17/2022] Open
Abstract
Second-order spinal cord excitatory neurons play a key role in spinal processing and transmission of pain signals to the brain. Exogenously-induced change in developmentally-imprinted excitatory neurotransmitter phenotype of these neurons to inhibitory has not yet been achieved. Here we use a subpial dorsal horn-targeted delivery of AAV (adeno-associated virus) vector(s) encoding GABA (gamma-Aminobutyric acid,) synthesizing-releasing inhibitory machinery in mice with neuropathic pain. Treated animals showed a progressive and complete reversal of neuropathic pain (tactile and brush-evoked pain behavior) which persisted for minimum 2.5 months post-treatment. The mechanism of this treatment effect results from the switch of excitatory to preferential inhibitory neurotransmitter phenotype in dorsal horn nociceptive neurons and a resulting increase in inhibitory activity in regional spinal circuitry after peripheral nociceptive stimulation. No detectable side effects (such as sedation, motor weakness or loss of normal sensation) were seen between 2-13 months post-treatment in naive adult mice, pigs and non-human primates. The use of this treatment approach may represent a potent and safe treatment modality in patients suffering from spinal cord- or peripheral nerve-injury induced neuropathic pain.
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Affiliation(s)
- Takahiro Tadokoro
- Neuroregeneration Laboratory, Department of Anesthesiology, University of California, San Diego (UCSD), La Jolla, CA 92037, USA; Department of Anesthesiology, University of Ryukyus, Okinawa, Japan; Neurgain Technologies, 9620 Towne Centre Drive, Suite 100, San Diego, CA 92121, USA
| | - Mariana Bravo-Hernandez
- Neuroregeneration Laboratory, Department of Anesthesiology, University of California, San Diego (UCSD), La Jolla, CA 92037, USA
| | - Kirill Agashkov
- Departments of Sensory Signaling and Molecular Biophysics, Bogomoletz Institute of Physiology, Kyiv, Ukraine
| | - Yoshiomi Kobayashi
- Neuroregeneration Laboratory, Department of Anesthesiology, University of California, San Diego (UCSD), La Jolla, CA 92037, USA
| | - Oleksandr Platoshyn
- Neuroregeneration Laboratory, Department of Anesthesiology, University of California, San Diego (UCSD), La Jolla, CA 92037, USA
| | - Michael Navarro
- Neuroregeneration Laboratory, Department of Anesthesiology, University of California, San Diego (UCSD), La Jolla, CA 92037, USA
| | - Silvia Marsala
- Neuroregeneration Laboratory, Department of Anesthesiology, University of California, San Diego (UCSD), La Jolla, CA 92037, USA; Neurgain Technologies, 9620 Towne Centre Drive, Suite 100, San Diego, CA 92121, USA
| | - Atsushi Miyanohara
- Neuroregeneration Laboratory, Department of Anesthesiology, University of California, San Diego (UCSD), La Jolla, CA 92037, USA; Vector Core Laboratory, University of California, San Diego (UCSD), La Jolla, CA 92037, USA
| | - Tetsuya Yoshizumi
- Neuroregeneration Laboratory, Department of Anesthesiology, University of California, San Diego (UCSD), La Jolla, CA 92037, USA
| | - Michiko Shigyo
- Neuroregeneration Laboratory, Department of Anesthesiology, University of California, San Diego (UCSD), La Jolla, CA 92037, USA
| | - Volodymyr Krotov
- Departments of Sensory Signaling and Molecular Biophysics, Bogomoletz Institute of Physiology, Kyiv, Ukraine
| | - Stefan Juhas
- Institute of Animal Physiology and Genetics, Czech Academy of Sciences, Rumburská 89, 277 21 Liběchov, Czech Republic
| | - Jana Juhasova
- Institute of Animal Physiology and Genetics, Czech Academy of Sciences, Rumburská 89, 277 21 Liběchov, Czech Republic
| | - Duong Nguyen
- Institute of Animal Physiology and Genetics, Czech Academy of Sciences, Rumburská 89, 277 21 Liběchov, Czech Republic
| | - Helena Kupcova Skalnikova
- Institute of Animal Physiology and Genetics, Czech Academy of Sciences, Rumburská 89, 277 21 Liběchov, Czech Republic
| | - Jan Motlik
- Institute of Animal Physiology and Genetics, Czech Academy of Sciences, Rumburská 89, 277 21 Liběchov, Czech Republic
| | - Hana Studenovska
- Institute of Macromolecular Chemistry, Czech Academy of Sciences, Department of Biomaterials and Bioanalogous Systems, Heyrovsky Square 2,162 06 Prague 6, Czech Republic
| | - Vladimir Proks
- Institute of Macromolecular Chemistry, Czech Academy of Sciences, Department of Biomaterials and Bioanalogous Systems, Heyrovsky Square 2,162 06 Prague 6, Czech Republic
| | - Rajiv Reddy
- Department of Anesthesiology, Pain Medicine, University of California, San Diego (UCSD), La Jolla, CA 92037, USA
| | - Shawn P Driscoll
- Gene Expression Laboratory and the Howard Hughes Medical Institute, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Thomas D Glenn
- Gene Expression Laboratory and the Howard Hughes Medical Institute, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Taratorn Kemthong
- National Primate Research Center of Thailand, Chulalongkorn University, Kaengkhoi District, Saraburi 18110, Thailand
| | - Suchinda Malaivijitnond
- National Primate Research Center of Thailand, Chulalongkorn University, Kaengkhoi District, Saraburi 18110, Thailand
| | - Zoltan Tomori
- Department of Biophysics, Institute of Experimental Physics, Slovak Academy of Sciences, Kosice, Slovakia
| | - Ivo Vanicky
- Institute of Neurobiology, Biomedical Research Center, Slovak Academy of Sciences, Kosice, Slovakia
| | | | - Samuel L Pfaff
- Gene Expression Laboratory and the Howard Hughes Medical Institute, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Joseph Ciacci
- Department of Neurosurgery, University of California, San Diego (UCSD), La Jolla, CA 92037, USA
| | - Pavel Belan
- Departments of Sensory Signaling and Molecular Biophysics, Bogomoletz Institute of Physiology, Kyiv, Ukraine; Kyiv Academic University, Kyiv, Ukraine
| | - Martin Marsala
- Neuroregeneration Laboratory, Department of Anesthesiology, University of California, San Diego (UCSD), La Jolla, CA 92037, USA; Institute of Neurobiology, Biomedical Research Center, Slovak Academy of Sciences, Kosice, Slovakia.
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5
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Ohashi N, Uta D, Ohashi M, Baba H. Norepinephrine restores inhibitory tone of spinal lamina X circuitry, thus contributing to analgesia against inflammatory pain. Neuroscience 2022; 490:224-235. [DOI: 10.1016/j.neuroscience.2022.03.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 03/12/2022] [Accepted: 03/16/2022] [Indexed: 10/18/2022]
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Chronic Stress and Gonadectomy Affect the Expression of Cx37, Cx40 and Cx43 in the Spinal Cord. Life (Basel) 2021; 11:life11121330. [PMID: 34947861 PMCID: PMC8706389 DOI: 10.3390/life11121330] [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: 09/08/2021] [Revised: 11/22/2021] [Accepted: 11/29/2021] [Indexed: 11/20/2022] Open
Abstract
The study aimed to determine whether the exposure to chronic stress and/or performance of gonadectomy might lead to disturbance in the expression of connexin (Cx) 37, 40 and 43 in the spinal cord (SC), as a potential explanation for sex differences in stress-related chronic pain conditions. After the rats were sham-operated or gonadectomized, three 10-day sessions of sham or chronic stress were applied. Immunohistochemistry and transmission electron microscopy (TEM) were used to examine Cx localization and expression in the SC. The gonadectomy resulted in an increase of Cx37 expression in the dorsal horn (DH) of the female rats, but chronic stress suppressed the effects of castration. In male rats, only the combined effects of castration and chronic stress increased Cx37 expression. The influence of chronic stress on the DH Cx40 expression was inversely evident after the castration: increased in the ovariectomized female rats, while decreased in the orchidectomized male rats. We did not find any effect of chronic stress and castration, alone or together, on Cx43 expression in the DH, but the percentage of Cx43 overlapping the astrocyte marker glial fibrillary acidic protein (gfap) increased in the male stressed group after the castration. In conclusion, the association of the chronic stress with sex hormone depletion results in disturbances of the SC Cx expression and might be a possible mechanism of disturbed pain perception after chronic stress exposure.
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7
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In Vivo Electrophysiology of Peptidergic Neurons in Deep Layers of the Lumbar Spinal Cord after Optogenetic Stimulation of Hypothalamic Paraventricular Oxytocin Neurons in Rats. Int J Mol Sci 2021; 22:ijms22073400. [PMID: 33810239 PMCID: PMC8036474 DOI: 10.3390/ijms22073400] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Revised: 03/22/2021] [Accepted: 03/23/2021] [Indexed: 01/28/2023] Open
Abstract
The spinal ejaculation generator (SEG) is located in the central gray (lamina X) of the rat lumbar spinal cord and plays a pivotal role in the ejaculatory reflex. We recently reported that SEG neurons express the oxytocin receptor and are activated by oxytocin projections from the paraventricular nucleus of hypothalamus (PVH). However, it is unknown whether the SEG responds to oxytocin in vivo. In this study, we analyzed the characteristics of the brain–spinal cord neural circuit that controls male sexual function using a newly developed in vivo electrophysiological technique. Optogenetic stimulation of the PVH of rats expressing channel rhodopsin under the oxytocin receptor promoter increased the spontaneous firing of most lamina X SEG neurons. This is the first demonstration of the in vivo electrical response from the deeper (lamina X) neurons in the spinal cord. Furthermore, we succeeded in the in vivo whole-cell recordings of lamina X neurons. In vivo whole-cell recordings may reveal the features of lamina X SEG neurons, including differences in neurotransmitters and response to stimulation. Taken together, these results suggest that in vivo electrophysiological stimulation can elucidate the neurophysiological response of a variety of spinal neurons during male sexual behavior.
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8
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Browne TJ, Hughes DI, Dayas CV, Callister RJ, Graham BA. Projection Neuron Axon Collaterals in the Dorsal Horn: Placing a New Player in Spinal Cord Pain Processing. Front Physiol 2020; 11:560802. [PMID: 33408637 PMCID: PMC7779806 DOI: 10.3389/fphys.2020.560802] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Accepted: 11/26/2020] [Indexed: 11/13/2022] Open
Abstract
The pain experience depends on the relay of nociceptive signals from the spinal cord dorsal horn to higher brain centers. This function is ultimately achieved by the output of a small population of highly specialized neurons called projection neurons (PNs). Like output neurons in other central nervous system (CNS) regions, PNs are invested with a substantial axon collateral system that ramifies extensively within local circuits. These axon collaterals are widely distributed within and between spinal cord segments. Anatomical data on PN axon collaterals have existed since the time of Cajal, however, their function in spinal pain signaling remains unclear and is absent from current models of spinal pain processing. Despite these omissions, some insight on the potential role of PN axon collaterals can be drawn from axon collateral systems of principal or output neurons in other CNS regions, such as the hippocampus, amygdala, olfactory cortex, and ventral horn of the spinal cord. The connectivity and actions of axon collaterals in these systems have been well-defined and used to confirm crucial roles in memory, fear, olfaction, and movement control, respectively. We review this information here and propose a framework for characterizing PN axon collateral function in the dorsal horn. We highlight that experimental approaches traditionally used to delineate axon collateral function in other CNS regions are not easily applied to PNs because of their scarcity relative to spinal interneurons (INs), and the lack of cellular organization in the dorsal horn. Finally, we emphasize how the rapid development of techniques such as viral expression of optogenetic or chemogenetic probes can overcome these challenges and allow characterization of PN axon collateral function. Obtaining detailed information of this type is a necessary first step for incorporation of PN collateral system function into models of spinal sensory processing.
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Affiliation(s)
- Tyler J Browne
- School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine, University of Newcastle, Callaghan, NSW, Australia.,Hunter Medical Research Institute (HMRI), New Lambton Heights, NSW, Australia
| | - David I Hughes
- Institute of Neuroscience Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Christopher V Dayas
- School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine, University of Newcastle, Callaghan, NSW, Australia.,Hunter Medical Research Institute (HMRI), New Lambton Heights, NSW, Australia
| | - Robert J Callister
- School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine, University of Newcastle, Callaghan, NSW, Australia.,Hunter Medical Research Institute (HMRI), New Lambton Heights, NSW, Australia
| | - Brett A Graham
- School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine, University of Newcastle, Callaghan, NSW, Australia.,Hunter Medical Research Institute (HMRI), New Lambton Heights, NSW, Australia
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Abstract
The spinal gray matter region around the central canal, lamina X, is critically involved in somatosensory processing and visceral nociception. Although several classes of primary afferent fibers terminate or decussate in this area, little is known about organization and functional significance of the afferent supply of lamina X neurons. Using the hemisected ex vivo spinal cord preparation, we show that virtually all lamina X neurons receive primary afferent inputs, which are predominantly mediated by the high-threshold Aδ- fibers and C-fibers. In two-thirds of the neurons tested, the inputs were monosynaptic, implying a direct targeting of the population of lamina X neurons by the primary nociceptors. Beside the excitatory inputs, 48% of the neurons also received polysynaptic inhibitory inputs. A complex pattern of interactions between the excitatory and inhibitory components determined the output properties of the neurons, one-third of which fired spikes in response to the nociceptive dorsal root stimulation. In this respect, the spinal gray matter region around the central canal is similar to the superficial dorsal horn, the major spinal nociceptive processing area. We conclude that lamina X neurons integrate direct and indirect inputs from several types of thin primary afferent fibers and play an important role in nociception.
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Vahdat S, Khatibi A, Lungu O, Finsterbusch J, Büchel C, Cohen-Adad J, Marchand-Pauvert V, Doyon J. Resting-state brain and spinal cord networks in humans are functionally integrated. PLoS Biol 2020; 18:e3000789. [PMID: 32614823 PMCID: PMC7363111 DOI: 10.1371/journal.pbio.3000789] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2020] [Revised: 07/15/2020] [Accepted: 06/15/2020] [Indexed: 01/04/2023] Open
Abstract
In the absence of any task, both the brain and spinal cord exhibit spontaneous intrinsic activity organised in a set of functionally relevant neural networks. However, whether such resting-state networks (RSNs) are interconnected across the brain and spinal cord is unclear. Here, we used a unique scanning protocol to acquire functional images of both brain and cervical spinal cord (CSC) simultaneously and examined their spatiotemporal correspondence in humans. We show that the brain and spinal cord activities are strongly correlated during rest periods, and specific spinal cord regions are functionally linked to consistently reported brain sensorimotor RSNs. The functional organisation of these networks follows well-established anatomical principles, including the contralateral correspondence between the spinal hemicords and brain hemispheres as well as sensory versus motor segregation of neural pathways along the brain–spinal cord axis. Thus, our findings reveal a unified functional organisation of sensorimotor networks in the entire central nervous system (CNS) at rest. This neuroimaging study reveals novel insights into the functional organization of resting-state networks in the brain and spinal cord, such as the contralateral correspondence between the two halves of the brain and spinal cord, and segregation of sensory versus motor neural pathways along this axis.
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Affiliation(s)
- Shahabeddin Vahdat
- Centre de recherche de l'Institut Universitaire de Gériatrie de Montréal, Montréal, Quebec, Canada.,Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida, United States of America
| | - Ali Khatibi
- McConnell Brain Imaging Center, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada.,Centre of Precision Rehabilitation for Spinal Pain (CPR Spine), University of Birmingham, Birmingham, United Kingdom
| | - Ovidiu Lungu
- Centre de recherche de l'Institut Universitaire de Gériatrie de Montréal, Montréal, Quebec, Canada.,McConnell Brain Imaging Center, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada.,Department of Psychiatry, University of Montreal, Montreal, Quebec, Canada
| | - Jürgen Finsterbusch
- Department of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Christian Büchel
- Department of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Julien Cohen-Adad
- Centre de recherche de l'Institut Universitaire de Gériatrie de Montréal, Montréal, Quebec, Canada.,NeuroPoly Lab, Department of Electrical Engineering, Polytechnique Montreal, Montreal, Quebec, Canada
| | | | - Julien Doyon
- Centre de recherche de l'Institut Universitaire de Gériatrie de Montréal, Montréal, Quebec, Canada.,McConnell Brain Imaging Center, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
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11
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Distinct mechanisms of signal processing by lamina I spino-parabrachial neurons. Sci Rep 2019; 9:19231. [PMID: 31848358 PMCID: PMC6917718 DOI: 10.1038/s41598-019-55462-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Accepted: 11/26/2019] [Indexed: 12/20/2022] Open
Abstract
Lamina I spino-parabrachial neurons (SPNs) receive peripheral nociceptive input, process it and transmit to the supraspinal centres. Although responses of SPNs to cutaneous receptive field stimulations have been intensively studied, the mechanisms of signal processing in these neurons are poorly understood. Therefore, we used an ex-vivo spinal cord preparation to examine synaptic and cellular mechanisms determining specific input-output characteristics of the neurons. The vast majority of the SPNs received a few direct nociceptive C-fiber inputs and generated one spike in response to saturating afferent stimulation, thus functioning as simple transducers of painful stimulus. However, 69% of afferent stimulation-induced action potentials in the entire SPN population originated from a small fraction (19%) of high-output neurons. These neurons received a larger number of direct Aδ- and C-fiber inputs, generated intrinsic bursts and efficiently integrated a local network activity via NMDA-receptor-dependent mechanisms. The high-output SPNs amplified and integrated the nociceptive input gradually encoding its intensity into the number of generated spikes. Thus, different mechanisms of signal processing allow lamina I SPNs to play distinct roles in nociception.
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12
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Propriospinal Neurons of L3-L4 Segments Involved in Control of the Rat External Urethral Sphincter. Neuroscience 2019; 425:12-28. [PMID: 31785359 DOI: 10.1016/j.neuroscience.2019.11.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 10/31/2019] [Accepted: 11/11/2019] [Indexed: 12/17/2022]
Abstract
Coordination of activity of external urethral sphincter (EUS) striated muscle and bladder (BL) smooth muscle is essential for efficient voiding. In this study we examined the morphological and electrophysiological properties of neurons in the L3/L4 spinal cord (SC) that are likely to have an important role in EUS-BL coordination in rats. EUS-related SC neurons were identified by retrograde transsynaptic tracing following injection of pseudorabies virus (PRV) co-expressing fluorescent markers into the EUS of P18-P20 male rats. Tracing revealed not only EUS motoneurons in L6/S1 but also interneurons in lamina X of the L6/S1 and L3/L4 SC. Physiological properties of fluorescently labeled neurons were assessed during whole-cell recordings in SC slices followed by reconstruction of biocytin-filled neurons. Reconstructions of neuronal processes from transverse or longitudinal slices showed that some L3/L4 neurons have axons projecting toward and into the ventro-medial funiculus (VMf) where axons extended caudally. Other neurons had axons projecting within laminae X and VII. Dendrites of L3/L4 neurons were distributed within laminae X and VII. The majority of L3/L4 neurons exhibited tonic firing in response to depolarizing currents. In transverse slices focal electrical stimulation (FES) in the VMf or in laminae X and VII elicited antidromic axonal spikes and/or excitatory synaptic responses in L3/L4 neurons; while in longitudinal slices FES elicited excitatory synaptic inputs from sites up to 400 μm along the central canal. Inhibitory inputs were rarely observed. These data suggest that L3/L4 EUS-related circuitry consists of at least two neuronal populations: segmental interneurons and propriospinal neurons projecting to L6/S1.
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Ohashi N, Ohashi M, Baba H. Action of Norepinephrine on Lamina X of the Spinal Cord. Neuroscience 2019; 408:214-225. [PMID: 30981866 DOI: 10.1016/j.neuroscience.2019.04.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 03/28/2019] [Accepted: 04/02/2019] [Indexed: 11/30/2022]
Abstract
Lamina X is localized in the spinal cord within the region surrounding the central canal and receives descending projections from the supraspinal nuclei. Norepinephrine (NE) is a neurotransmitter in descending pathways emanating from the brain stem; NE-containing fibers terminate in the spinal dorsal cord, particularly in the substantia gelatinosa (SG). NE enhances inhibitory synaptic transmission in SG neurons by activating presynaptic α1-receptors and hyperpolarizes the membranes of SG neurons by acting on α2-receptors; NE may thus act directly on SG neurons of the dorsal spinal cord and inhibit nociceptive transmission at the spinal level. NE-containing fibers also reportedly terminate in lamina X, suggesting that NE also modulates synaptic transmission in lamina X. However, the cellular mechanisms underlying such action have not been investigated. We hypothesized that NE might directly act on lamina X and enhance inhibitory synaptic transmission therein. Using rat spinal cord slices and in vitro whole-cell patch-clamps, we found that the bath-application of NE to lamina X does not affect the excitatory interneurons but enhances GABAergic and glycinergic miniature inhibitory postsynaptic currents (mIPSCs) and induces an outward current. NE-induced enhancement of mIPSCs was blocked by α1A-receptor antagonists, and NE-induced outward current was blocked by α2-receptor antagonists. NE did not affect GABA- or glycine- induced outward currents. These findings are similar to those obtained from SG neurons: NE may act at presynaptic terminals of GABAergic and glycinergic interneurons on lamina X to facilitate inhibitory-transmitter release through α1A-receptor activation and directly induce inhibitory interneuron membrane hyperpolarization through α2-receptors activation.
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Affiliation(s)
- Nobuko Ohashi
- Division of Anesthesiology, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi Dori, Chuo-Ku, Niigata City, Niigata 951-8510, Japan.
| | - Masayuki Ohashi
- Division of Orthopedic Surgery, Department of Regenerative and Transplant Medicine, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi Dori, Chuo-Ku, Niigata City, Niigata 951-8510, Japan
| | - Hiroshi Baba
- Division of Anesthesiology, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi Dori, Chuo-Ku, Niigata City, Niigata 951-8510, Japan
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