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Zaforas M, Miguel-Quesada C, Fernández-López E, Alonso-Calviño E, Barranco-Maresca V, Misol-Ortiz A, Aguilar J, Rosa JM. Protocol for stimulating specific rodent limb receptive fields while recording in vivo somatosensory-evoked activity. STAR Protoc 2024; 5:102972. [PMID: 38502685 PMCID: PMC10960094 DOI: 10.1016/j.xpro.2024.102972] [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: 01/02/2024] [Revised: 02/06/2024] [Accepted: 03/05/2024] [Indexed: 03/21/2024] Open
Abstract
Studies on sensory information processing typically focus on whisker-related tactile information, overlooking the question of how sensory inputs from other body areas are processed at cortical levels. Here, we present a protocol for stimulating specific rodent limb receptive fields while recording in vivo somatosensory-evoked activity. We describe steps for localizing cortical-hindlimb coordinates using acute peripheral stimulation, electrode placement, and the application of electrical stimulation. This protocol overcomes the challenge of inducing a reproducible and consistent stimulation of specific limbs. For complete details on the use and execution of this protocol, please refer to Miguel-Quesada et al.1.
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Affiliation(s)
- Marta Zaforas
- Experimental Neurophysiology Group, Hospital Nacional de Parapléjicos. SESCAM, 45071 Toledo, Spain; Instituto de Investigación Sanitaria de Castilla-La Mancha (IDISCAM), 45071 Toledo, Spain.
| | - Claudia Miguel-Quesada
- Experimental Neurophysiology Group, Hospital Nacional de Parapléjicos. SESCAM, 45071 Toledo, Spain; Neuronal Circuits and Behaviour Group, Hospital Nacional de Parapléjicos, 45071 Toledo, Spain
| | - Elena Fernández-López
- Experimental Neurophysiology Group, Hospital Nacional de Parapléjicos. SESCAM, 45071 Toledo, Spain; Instituto de Investigación Sanitaria de Castilla-La Mancha (IDISCAM), 45071 Toledo, Spain
| | - Elena Alonso-Calviño
- Experimental Neurophysiology Group, Hospital Nacional de Parapléjicos. SESCAM, 45071 Toledo, Spain; Instituto de Investigación Sanitaria de Castilla-La Mancha (IDISCAM), 45071 Toledo, Spain
| | - Verónica Barranco-Maresca
- Neuronal Circuits and Behaviour Group, Hospital Nacional de Parapléjicos, 45071 Toledo, Spain; Instituto de Investigación Sanitaria de Castilla-La Mancha (IDISCAM), 45071 Toledo, Spain
| | - Andrea Misol-Ortiz
- Experimental Neurophysiology Group, Hospital Nacional de Parapléjicos. SESCAM, 45071 Toledo, Spain; Instituto de Investigación Sanitaria de Castilla-La Mancha (IDISCAM), 45071 Toledo, Spain
| | - Juan Aguilar
- Experimental Neurophysiology Group, Hospital Nacional de Parapléjicos. SESCAM, 45071 Toledo, Spain; Instituto de Investigación Sanitaria de Castilla-La Mancha (IDISCAM), 45071 Toledo, Spain
| | - Juliana M Rosa
- Neuronal Circuits and Behaviour Group, Hospital Nacional de Parapléjicos, 45071 Toledo, Spain; Instituto de Investigación Sanitaria de Castilla-La Mancha (IDISCAM), 45071 Toledo, Spain.
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2
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Alonso-Calviño E, Fernández-López E, Zaforas M, Rosa JM, Aguilar J. Increased excitability and reduced GABAergic levels in somatosensory cortex under chronic spinal cord injury. Exp Neurol 2023; 369:114504. [PMID: 37591355 DOI: 10.1016/j.expneurol.2023.114504] [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: 04/29/2023] [Revised: 07/07/2023] [Accepted: 08/11/2023] [Indexed: 08/19/2023]
Abstract
The complete or partial damage of ascending somatosensory pathways produced by a spinal cord injury triggers changes in the somatosensory cortex consisting in a functional expansion of activity from intact cortical regions towards deafferented ones, a process known as cortical reorganization. However, it is still unclear whether cortical reorganization depends on the severity of the spinal cord damage or if a spinal cord injury always leads to a similar cortical reorganization process in the somatosensory cortex. To answer these open questions in the field, we obtained longitudinal somatosensory evoked responses from bilateral hindlimb and forelimb cortex from animals with chronic full-transection or contusive spinal cord injury at thoracic level (T9-T10) to induce sensory deprivation of hindlimb cortex while preserving intact the forelimb cortex. Electrophysiological recordings from the four locations were obtained before lesion and weekly for up to 4 weeks. Our results show that cortical reorganization depends on the type of spinal cord injury, which tends to be more bilateral in full transection while is more unilateral in the model of contusive spinal cord injury. Moreover, in full transection of spinal cord, the deafferented and intact cortex exhibited similar increments of somatosensory evoked responses in both models of spinal cord injury - a feature observed in about 80% of subjects. The other 20% were unaffected by the injury indicating that cortical reorganization does not undergo in all subjects. In addition, we demonstrated an increased probability of triggered up-states in animals with spinal cord injury. This data indicates increased cortical excitability that could be proposed as a new feature of cortical reorganization. Finally, decreased levels of GABA marker GAD67 across cortical layers were only found in those animals with increased somatosensory evoked responses, but not in the unaffected population. In conclusion, cortical reorganization depends on the types of spinal cord injuries, and suggest that the phenomenon is strongly determined by cortical circuits. Moreover, changes in GABAergic transmission at the deprived cortex may be considered one of the mechanisms underlying the process of cortical reorganization and increased excitability.
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Affiliation(s)
- Elena Alonso-Calviño
- Experimental Neurophysiology Group, Hospital Nacional de Parapléjicos, SESCAM, Toledo, Spain; Instituto de Investigación Sanitaria de Castilla-La Mancha (IDISCAM), Toledo, Spain
| | - Elena Fernández-López
- Experimental Neurophysiology Group, Hospital Nacional de Parapléjicos, SESCAM, Toledo, Spain; Instituto de Investigación Sanitaria de Castilla-La Mancha (IDISCAM), Toledo, Spain
| | - Marta Zaforas
- Experimental Neurophysiology Group, Hospital Nacional de Parapléjicos, SESCAM, Toledo, Spain; Instituto de Investigación Sanitaria de Castilla-La Mancha (IDISCAM), Toledo, Spain
| | - Juliana M Rosa
- Neuronal Circuits and Behaviour Group, Hospital Nacional de Parapléjicos, SESCAM, Toledo, Spain; Instituto de Investigación Sanitaria de Castilla-La Mancha (IDISCAM), Toledo, Spain
| | - Juan Aguilar
- Experimental Neurophysiology Group, Hospital Nacional de Parapléjicos, SESCAM, Toledo, Spain; Instituto de Investigación Sanitaria de Castilla-La Mancha (IDISCAM), Toledo, Spain.
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Miguel-Quesada C, Zaforas M, Herrera-Pérez S, Lines J, Fernández-López E, Alonso-Calviño E, Ardaya M, Soria FN, Araque A, Aguilar J, Rosa JM. Astrocytes adjust the dynamic range of cortical network activity to control modality-specific sensory information processing. Cell Rep 2023; 42:112950. [PMID: 37543946 DOI: 10.1016/j.celrep.2023.112950] [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] [Received: 10/19/2022] [Revised: 03/21/2023] [Accepted: 07/23/2023] [Indexed: 08/08/2023] Open
Abstract
Cortical neuron-astrocyte communication in response to peripheral sensory stimulation occurs in a topographic-, frequency-, and intensity-dependent manner. However, the contribution of this functional interaction to the processing of sensory inputs and consequent behavior remains unclear. We investigate the role of astrocytes in sensory information processing at circuit and behavioral levels by monitoring and manipulating astrocytic activity in vivo. We show that astrocytes control the dynamic range of the cortical network activity, optimizing its responsiveness to incoming sensory inputs. The astrocytic modulation of sensory processing contributes to setting the detection threshold for tactile and thermal behavior responses. The mechanism of such astrocytic control is mediated through modulation of inhibitory transmission to adjust the gain and sensitivity of responding networks. These results uncover a role for astrocytes in maintaining the cortical network activity in an optimal range to control behavior associated with specific sensory modalities.
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Affiliation(s)
- Claudia Miguel-Quesada
- Neuronal Circuits and Behaviour Group, Hospital Nacional de Parapléjicos, Instituto de Investigación Sanitaria de Castilla-La Mancha (IDISCAM), 45071 Toledo, Spain; Experimental Neurophysiology Group, Hospital Nacional de Parapléjicos, Instituto de Investigación Sanitaria de Castilla-La Mancha (IDISCAM), 45071 Toledo, Spain
| | - Marta Zaforas
- Experimental Neurophysiology Group, Hospital Nacional de Parapléjicos, Instituto de Investigación Sanitaria de Castilla-La Mancha (IDISCAM), 45071 Toledo, Spain
| | - Salvador Herrera-Pérez
- Experimental Neurophysiology Group, Hospital Nacional de Parapléjicos, Instituto de Investigación Sanitaria de Castilla-La Mancha (IDISCAM), 45071 Toledo, Spain
| | - Justin Lines
- Department of Neuroscience, University of Minnesota, Minneapolis, MN 55455, USA
| | - Elena Fernández-López
- Experimental Neurophysiology Group, Hospital Nacional de Parapléjicos, Instituto de Investigación Sanitaria de Castilla-La Mancha (IDISCAM), 45071 Toledo, Spain
| | - Elena Alonso-Calviño
- Experimental Neurophysiology Group, Hospital Nacional de Parapléjicos, Instituto de Investigación Sanitaria de Castilla-La Mancha (IDISCAM), 45071 Toledo, Spain
| | - Maria Ardaya
- Donostia International Physics Center (DIPC), 20018 San Sebastian, Spain; Achucarro Basque Center for Neuroscience, 48940 Leioa, Spain
| | - Federico N Soria
- Achucarro Basque Center for Neuroscience, 48940 Leioa, Spain; Ikerbasque, Basque Foundation for Science, 48009 Bilbao, Spain; Centro de Investigación Biomédica en Red Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Alfonso Araque
- Department of Neuroscience, University of Minnesota, Minneapolis, MN 55455, USA
| | - Juan Aguilar
- Experimental Neurophysiology Group, Hospital Nacional de Parapléjicos, Instituto de Investigación Sanitaria de Castilla-La Mancha (IDISCAM), 45071 Toledo, Spain.
| | - Juliana M Rosa
- Neuronal Circuits and Behaviour Group, Hospital Nacional de Parapléjicos, Instituto de Investigación Sanitaria de Castilla-La Mancha (IDISCAM), 45071 Toledo, Spain.
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4
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Zaforas M, Rosa JM, Alonso-Calviño E, Fernández-López E, Miguel-Quesada C, Oliviero A, Aguilar J. Cortical layer-specific modulation of neuronal activity after sensory deprivation due to spinal cord injury. J Physiol 2021; 599:4643-4669. [PMID: 34418097 PMCID: PMC9292026 DOI: 10.1113/jp281901] [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: 05/11/2021] [Accepted: 08/19/2021] [Indexed: 11/28/2022] Open
Abstract
Abstract Cortical areas have the capacity of large‐scale reorganization following sensory deafferentation. However, it remains unclear whether this phenomenon is a unique process that homogeneously affects the entire deprived cortical region or whether it is susceptible to changes depending on neuronal networks across distinct cortical layers. Here, we studied how the local circuitry within each layer of the deafferented cortex forms the basis for neuroplastic changes after immediate thoracic spinal cord injury (SCI) in anaesthetized rats. In vivo electrophysiological recordings from deafferented hindlimb somatosensory cortex showed that SCI induces layer‐specific changes mediating evoked and spontaneous activity. In supragranular layer 2/3, SCI increased gamma oscillations and the ability of these neurons to initiate up‐states during spontaneous activity, suggesting an altered corticocortical network and/or intrinsic properties that may serve to maintain the excitability of the cortical column after deafferentation. On the other hand, SCI enhanced the infragranular layers’ ability to integrate evoked sensory inputs leading to increased and faster neuronal responses. Delayed evoked response onsets were also observed in layer 5/6, suggesting alterations in thalamocortical connectivity. Altogether, our data indicate that SCI immediately modifies the local circuitry within the deafferented cortex allowing supragranular layers to better integrate spontaneous corticocortical information, thus modifying column excitability, and infragranular layers to better integrate evoked sensory inputs to preserve subcortical outputs. These layer‐specific neuronal changes may guide the long‐term alterations in neuronal excitability and plasticity associated with the rearrangements of somatosensory networks and the appearance of central sensory pathologies usually associated with spinal cord injury. Key points Sensory stimulation of forelimb produces cortical evoked responses in the somatosensory hindlimb cortex in a layer‐dependent manner. Spinal cord injury favours the input statistics of corticocortical connections between intact and deafferented cortices. After spinal cord injury supragranular layers exhibit better integration of spontaneous corticocortical information while infragranular layers exhibit better integration of evoked sensory stimulation. Cortical reorganization is a layer‐specific phenomenon.
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Affiliation(s)
- Marta Zaforas
- Experimental Neurophysiology and Neuronal Circuits Group, Research Unit, Hospital Nacional de Parapléjicos - SESCAM, Toledo, 45071, Spain.,FENNSI Group, Hospital Nacional de Parapléjicos - SESCAM, Research Unit, Toledo, 45071, Spain
| | - Juliana M Rosa
- Experimental Neurophysiology and Neuronal Circuits Group, Research Unit, Hospital Nacional de Parapléjicos - SESCAM, Toledo, 45071, Spain
| | - Elena Alonso-Calviño
- Experimental Neurophysiology and Neuronal Circuits Group, Research Unit, Hospital Nacional de Parapléjicos - SESCAM, Toledo, 45071, Spain
| | - Elena Fernández-López
- Experimental Neurophysiology and Neuronal Circuits Group, Research Unit, Hospital Nacional de Parapléjicos - SESCAM, Toledo, 45071, Spain
| | - Claudia Miguel-Quesada
- Experimental Neurophysiology and Neuronal Circuits Group, Research Unit, Hospital Nacional de Parapléjicos - SESCAM, Toledo, 45071, Spain
| | - Antonio Oliviero
- FENNSI Group, Hospital Nacional de Parapléjicos - SESCAM, Research Unit, Toledo, 45071, Spain
| | - Juan Aguilar
- Experimental Neurophysiology and Neuronal Circuits Group, Research Unit, Hospital Nacional de Parapléjicos - SESCAM, Toledo, 45071, Spain
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5
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Nandakumar B, Blumenthal GH, Pauzin FP, Moxon KA. Hindlimb Somatosensory Information Influences Trunk Sensory and Motor Cortices to Support Trunk Stabilization. Cereb Cortex 2021; 31:5165-5187. [PMID: 34165153 DOI: 10.1093/cercor/bhab150] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 04/10/2021] [Accepted: 04/27/2021] [Indexed: 11/14/2022] Open
Abstract
Sensorimotor integration in the trunk system is poorly understood despite its importance for functional recovery after neurological injury. To address this, a series of mapping studies were performed in the rat. First, the receptive fields (RFs) of cells recorded from thoracic dorsal root ganglia were identified. Second, the RFs of cells recorded from trunk primary sensory cortex (S1) were used to assess the extent and internal organization of trunk S1. Finally, the trunk motor cortex (M1) was mapped using intracortical microstimulation to assess coactivation of trunk muscles with hindlimb and forelimb muscles, and integration with S1. Projections from trunk S1 to trunk M1 were not anatomically organized, with relatively weak sensorimotor integration between trunk S1 and M1 compared to extensive integration between hindlimb S1/M1 and trunk M1. Assessment of response latency and anatomical tracing suggest that trunk M1 is abundantly guided by hindlimb somatosensory information that is derived primarily from the thalamus. Finally, neural recordings from awake animals during unexpected postural perturbations support sensorimotor integration between hindlimb S1 and trunk M1, providing insight into the role of the trunk system in postural control that is useful when studying recovery after injury.
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Affiliation(s)
- Bharadwaj Nandakumar
- Department of Biomedical Engineering, Science, and Health Systems, Drexel University, Philadelphia, 19104 PA, USA.,Department of Biomedical Engineering, University of California, Davis, 95616 CA, USA
| | - Gary H Blumenthal
- Department of Biomedical Engineering, Science, and Health Systems, Drexel University, Philadelphia, 19104 PA, USA.,Department of Biomedical Engineering, University of California, Davis, 95616 CA, USA
| | | | - Karen A Moxon
- Department of Biomedical Engineering, Science, and Health Systems, Drexel University, Philadelphia, 19104 PA, USA.,Department of Biomedical Engineering, University of California, Davis, 95616 CA, USA.,Center for Neuroscience, Davis, 95618 CA, USA
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6
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Claron J, Hingot V, Rivals I, Rahal L, Couture O, Deffieux T, Tanter M, Pezet S. Large-scale functional ultrasound imaging of the spinal cord reveals in-depth spatiotemporal responses of spinal nociceptive circuits in both normal and inflammatory states. Pain 2021; 162:1047-1059. [PMID: 32947542 PMCID: PMC7977620 DOI: 10.1097/j.pain.0000000000002078] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 07/28/2020] [Accepted: 08/20/2020] [Indexed: 12/13/2022]
Abstract
Despite a century of research on the physiology/pathophysiology of the spinal cord in chronic pain condition, the properties of the spinal cord were rarely studied at the large-scale level from a neurovascular point of view. This is mostly due to the limited spatial and/or temporal resolution of the available techniques. Functional ultrasound imaging (fUS) is an emerging neuroimaging approach that allows, through the measurement of cerebral blood volume, the study of brain functional connectivity or functional activations with excellent spatial (100 μm) and temporal (1 msec) resolutions and a high sensitivity. The aim of this study was to increase our understanding of the spinal cord physiology through the study of the properties of spinal hemodynamic response to the natural or electrical stimulation of afferent fibers. Using a combination of fUS and ultrasound localization microscopy, the first step of this study was the fine description of the vascular structures in the rat spinal cord. Then, using either natural or electrical stimulations of different categories of afferent fibers (Aβ, Aδ, and C fibers), we could define the characteristics of the typical hemodynamic response of the rat spinal cord experimentally. We showed that the responses are fiber-specific, located ipsilaterally in the dorsal horn, and that they follow the somatotopy of afferent fiber entries in the dorsal horn and that the C-fiber response is an N-methyl-D-aspartate receptor-dependent mechanism. Finally, fUS imaging of the mesoscopic hemodynamic response induced by natural tactile stimulations revealed a potentiated response in inflammatory condition, suggesting an enhanced response to allodynic stimulations.
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Affiliation(s)
- Julien Claron
- Laboratory of Brain Plasticity, ESPCI Paris, PSL Research University, CNRS UMR 8249, Paris, France
- Physics for Medicine Paris, Inserm, ESPCI Paris, CNRS, PSL Research, University, Paris, France
| | - Vincent Hingot
- Physics for Medicine Paris, Inserm, ESPCI Paris, CNRS, PSL Research, University, Paris, France
| | - Isabelle Rivals
- Equipe de Statistique Appliquée, ESPCI Paris, PSL Research University, CNRS UMRS 1158, Paris, France
| | - Line Rahal
- Laboratory of Brain Plasticity, ESPCI Paris, PSL Research University, CNRS UMR 8249, Paris, France
- Physics for Medicine Paris, Inserm, ESPCI Paris, CNRS, PSL Research, University, Paris, France
| | - Olivier Couture
- Physics for Medicine Paris, Inserm, ESPCI Paris, CNRS, PSL Research, University, Paris, France
| | - Thomas Deffieux
- Physics for Medicine Paris, Inserm, ESPCI Paris, CNRS, PSL Research, University, Paris, France
| | - Mickael Tanter
- Physics for Medicine Paris, Inserm, ESPCI Paris, CNRS, PSL Research, University, Paris, France
| | - Sophie Pezet
- Laboratory of Brain Plasticity, ESPCI Paris, PSL Research University, CNRS UMR 8249, Paris, France
- Physics for Medicine Paris, Inserm, ESPCI Paris, CNRS, PSL Research, University, Paris, France
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7
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Cha M, Choi S, Kim K, Lee BH. Manganese-enhanced MRI depicts a reduction in brain responses to nociception upon mTOR inhibition in chronic pain rats. Mol Brain 2020; 13:158. [PMID: 33267907 PMCID: PMC7713325 DOI: 10.1186/s13041-020-00687-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 10/17/2020] [Indexed: 11/30/2022] Open
Abstract
Neuropathic pain induced by a nerve injury can lead to chronic pain. Recent studies have reported hyperactive neural activities in the nociceptive-related area of the brain as a result of chronic pain. Although cerebral activities associated with hyperalgesia and allodynia in chronic pain models are difficult to represent with functional imaging techniques, advances in manganese (Mn)-enhanced magnetic resonance imaging (MEMRI) could facilitate the visualization of the activation of pain-specific neural responses in the cerebral cortex. In order to investigate the alleviation of pain nociception by mammalian target of rapamycin (mTOR) modulation, we observed cerebrocortical excitability changes and compared regional Mn2+ enhancement after mTOR inhibition. At day 7 after nerve injury, drugs were applied into the intracortical area, and drug (Vehicle, Torin1, and XL388) effects were compared within groups using MEMRI. Therein, signal intensities of the insular cortex (IC), primary somatosensory cortex of the hind limb region, motor cortex 1/2, and anterior cingulate cortex regions were significantly reduced after application of mTOR inhibitors (Torin1 and XL388). Furthermore, rostral-caudal analysis of the IC indicated that the rostral region of the IC was more strongly associated with pain perception than the caudal region. Our data suggest that MEMRI can depict pain-related signal changes in the brain and that mTOR inhibition is closely correlated with pain modulation in chronic pain rats.
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Affiliation(s)
- Myeounghoon Cha
- Department of Physiology, Yonsei University College of Medicine, 50-1, Yonsei-ro, Seodaemun-gu, 03722, Seoul, Republic of Korea.
| | - Songyeon Choi
- Department of Physiology, Yonsei University College of Medicine, 50-1, Yonsei-ro, Seodaemun-gu, 03722, Seoul, Republic of Korea.,Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, 03722, Seoul, Republic of Korea
| | - Kyeongmin Kim
- Department of Physiology, Yonsei University College of Medicine, 50-1, Yonsei-ro, Seodaemun-gu, 03722, Seoul, Republic of Korea.,Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, 03722, Seoul, Republic of Korea
| | - Bae Hwan Lee
- Department of Physiology, Yonsei University College of Medicine, 50-1, Yonsei-ro, Seodaemun-gu, 03722, Seoul, Republic of Korea. .,Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, 03722, Seoul, Republic of Korea.
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8
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Lines J, Martin ED, Kofuji P, Aguilar J, Araque A. Astrocytes modulate sensory-evoked neuronal network activity. Nat Commun 2020; 11:3689. [PMID: 32704144 PMCID: PMC7378834 DOI: 10.1038/s41467-020-17536-3] [Citation(s) in RCA: 75] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Accepted: 07/01/2020] [Indexed: 11/12/2022] Open
Abstract
While neurons principally mediate brain function, astrocytes are emerging as cells with important neuromodulatory actions in brain physiology. In addition to homeostatic roles, astrocytes respond to neurotransmitters with calcium transients stimulating the release of gliotransmitters that regulate synaptic and neuronal functions. We investigated astrocyte-neuronal network interactions in vivo by combining two-photon microscopy to monitor astrocyte calcium and electrocorticogram to record neuronal network activity in the somatosensory cortex during sensory stimulation. We found astrocytes respond to sensory stimuli in a stimulus-dependent manner. Sensory stimuli elicit a surge of neuronal network activity in the gamma range (30-50 Hz) followed by a delayed astrocyte activity that dampens the steady-state gamma activity. This sensory-evoked gamma activity increase is enhanced in transgenic mice with impaired astrocyte calcium signaling and is decreased by pharmacogenetic stimulation of astrocytes. Therefore, cortical astrocytes respond to sensory inputs and regulate sensory-evoked neuronal network activity maximizing its dynamic range.
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Affiliation(s)
- Justin Lines
- Department of Neuroscience, University of Minnesota, 321 Church St SE, Minneapolis, MN, 55455, USA
| | | | - Paulo Kofuji
- Department of Neuroscience, University of Minnesota, 321 Church St SE, Minneapolis, MN, 55455, USA
| | - Juan Aguilar
- Experimental Neurophysiology, Hospital Nacional de Parapléjicos SESCAM, Finca La Peraleda s/n, 45071, Toledo, Spain.
| | - Alfonso Araque
- Department of Neuroscience, University of Minnesota, 321 Church St SE, Minneapolis, MN, 55455, USA.
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9
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Reorganization of the somatosensory pathway after subacute incomplete cervical cord injury. NEUROIMAGE-CLINICAL 2019; 21:101674. [PMID: 30642754 PMCID: PMC6412100 DOI: 10.1016/j.nicl.2019.101674] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2018] [Revised: 12/07/2018] [Accepted: 01/08/2019] [Indexed: 12/11/2022]
Abstract
Objective The main purpose of the present study was to investigate the possible somatosensory-related brain functional reorganization after traumatic spinal cord injury (SCI). Methods Thirteen patients with subacute incomplete cervical cord injury (ICCI) and thirteen age- and sex-matched healthy controls (HCs) were recruited. Eleven patients and all the HCs underwent both sensory task-related brain functional scanning and whole brain structural scanning on a 3.0 Tesla MRI system, and two patients underwent only structural scanning; the process of structural scanning was completed on thirteen patients, while functional scanning was only applied to eleven patients. We performed sensory task-related functional MRI (fMRI) to investigate the functional changes in the brain. In addition, voxel-based morphometry (VBM) was applied to explore whether any sensory-related brain structural changes occur in the whole brain after SCI. Results Compared with HCs, ICCI patients exhibited decreased activation in the left postcentral gyrus (postCG), the brainstem (midbrain and right pons) and the right cerebellar lobules IV-VI. Moreover, a significant positive association was found between the activation in the left PostCG and the activation in both the brainstem and the right cerebellar lobules IV-VI. Additionally, the decrease in gray matter volume (GMV) was detected in the left superior parietal lobule (SPL). The decrease of white matter volume (WMV) was observed in the right temporal lobe, the right occipital lobe, and the right calcarine gyrus. No structural change in the primary sensory cortex (S1), the secondary somatosensory cortex (S2) or the thalamus was detected. Conclusion These functional and structural findings may demonstrate the existence of an alternative pathway in the impairment of somatosensory function after SCI, which consists of the ipsilateral cerebellum, the brainstem and the contralateral postCG. It provides a new theoretical basis for the mechanism of sensory-related brain alteration in SCI patients and the rehabilitation therapy based on this pathway in the future. We found that sensory-related brain reorganization may not occur in the thalamus in patients with ICCI. We found that brain structural reorganization did not occur in the S1 or the S2 in patients with ICCI. We observed that SCI can cause brain structural reorganization in non-sensory-related areas. We observed that an alternative pathway may exist in the impairment of somatosensory function after SCI.
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10
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Jia Y, Shen Z, Lin G, Nie T, Zhang T, Wu R. Lumbar Spinal Cord Activity and Blood Biochemical Changes in Individuals With Diabetic Peripheral Neuropathy During Electrical Stimulation. Front Neurol 2019; 10:222. [PMID: 30936849 PMCID: PMC6431615 DOI: 10.3389/fneur.2019.00222] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Accepted: 02/20/2019] [Indexed: 02/05/2023] Open
Abstract
It is difficult to perform an in vivo evaluation of the nerve conduction mechanism in a patient with diabetic peripheral neuropathy (DPN). We aim to explore possible activation differences to enable a further understanding of the nerve conduction mechanisms of diabetic neuropathy and to present a novel clinical method to evaluate nerve injury and recovery. DPN patients (n = 20) and healthy volunteers (n = 20) were included in this study to detect the functional activation of the lumbar spinal cord via electric stimulation. Spinal fMRI data sets were acquired via a single-shot fast spin echo (SSFSE) sequence. A task-related fMRI was performed via low-frequency electrical stimulation. After post-processing, the active voxels and the percentage of signal changes were calculated for the DPN evaluation and the correlations between the blood biochemical indexes, such as glucose, total cholesterol, and hemoglobin A1c were explored. Activation in the DPN patients was primarily observed in the T12 (10/13) vertebral level. The percentage of signal changes in DPN patients was higher than that in the control group (Z = -2.757, P < 0.05). Positive correlation between the percentage of signal changes and the total cholesterol/glucose in the DNP group was found (P < 0.05). Lumbar spinal cord fMRI, based on the SEEP effect, was determined to be feasible. The repetitive activation distribution was primarily located at the T12 vertebral level. Lumbar spinal cord fMRI might be used as a potential tool to assess and reveal the nerve conduction mechanisms in DPN.
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Affiliation(s)
- Yanlong Jia
- Department of Medical Imaging, Second Affiliated Hospital, Shantou University Medical College, Shantou, China
| | - Zhiwei Shen
- Department of Medical Imaging, Second Affiliated Hospital, Shantou University Medical College, Shantou, China
| | - Guisen Lin
- Department of Medical Imaging, Second Affiliated Hospital, Shantou University Medical College, Shantou, China
| | - Tingting Nie
- Department of Medical Imaging, Second Affiliated Hospital, Shantou University Medical College, Shantou, China
| | - Tao Zhang
- Department of Medical Imaging, Second Affiliated Hospital, Shantou University Medical College, Shantou, China
| | - Renhua Wu
- Department of Medical Imaging, Second Affiliated Hospital, Shantou University Medical College, Shantou, China
- Provincial Key Laboratory of Medical Molecular Imaging, Shantou University Medical College, Shantou, China
- *Correspondence: Renhua Wu
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11
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Paquette T, Jeffrey-Gauthier R, Leblond H, PichÉ M. Functional Neuroimaging of Nociceptive and Pain-Related Activity in the Spinal Cord and Brain: Insights From Neurovascular Coupling Studies. Anat Rec (Hoboken) 2018; 301:1585-1595. [PMID: 29752872 DOI: 10.1002/ar.23854] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 03/22/2018] [Accepted: 03/31/2018] [Indexed: 12/12/2022]
Abstract
Spinal cord and brain processes underlie pain perception, which produces systemic cardiovascular changes. In turn, the autonomic nervous system regulates vascular function in the spinal cord and brain in order to adapt to these systemic changes, while neuronal activity induces local vascular changes. Thus, autonomic regulation and pain processes in the brain and spinal cord are tightly linked and interrelated. The objective of this topical review is to discuss work on neurovascular coupling during nociceptive processing in order to highlight supporting evidence and limitations for the use of cerebral and spinal fMRI to investigate pain mechanisms and spinal nociceptive processes. Work on functional neuroimaging of pain is presented and discussed in relation to available neurovascular coupling studies and related issues. Perspectives on future work are also discussed with an emphasis on differences between the brain and the spinal cord and on different approaches that may be useful to improve current methods, data analyses and interpretation. In summary, this review highlights the lack of data on neurovascular coupling during nociceptive stimulation and indicates that hemodynamic and BOLD responses measured with fMRI may be biased by nonspecific vascular changes. Future neuroimaging studies on nociceptive and pain-related processes would gain further understanding of neurovascular coupling in the brain and spinal cord and should take into account the effects of systemic vascular changes that may affect hemodynamic responses. Anat Rec, 301:1585-1595, 2018. © 2018 Wiley Periodicals, Inc.
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Affiliation(s)
- Thierry Paquette
- Department of Chiropractic, Université du Québec à Trois-Rivières, Trois-Rivières, Canada.,CogNAC Research Group, Université du Québec à Trois-Rivières, Trois-Rivières, Canada.,Department of Anatomy, Université du Québec à Trois-Rivières, Trois-Rivières, QC, Canada
| | - Renaud Jeffrey-Gauthier
- Department of Chiropractic, Université du Québec à Trois-Rivières, Trois-Rivières, Canada.,CogNAC Research Group, Université du Québec à Trois-Rivières, Trois-Rivières, Canada.,Department of Anatomy, Université du Québec à Trois-Rivières, Trois-Rivières, QC, Canada
| | - Hugues Leblond
- CogNAC Research Group, Université du Québec à Trois-Rivières, Trois-Rivières, Canada.,Department of Anatomy, Université du Québec à Trois-Rivières, Trois-Rivières, QC, Canada
| | - Mathieu PichÉ
- Department of Chiropractic, Université du Québec à Trois-Rivières, Trois-Rivières, Canada.,CogNAC Research Group, Université du Québec à Trois-Rivières, Trois-Rivières, Canada
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12
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Hama N, Kawai M, Ito SI, Hirota A. Optical study of interactions among propagation waves of neural excitation in the rat somatosensory cortex evoked by forelimb and hindlimb stimuli. J Neurophysiol 2018; 119:1934-1946. [DOI: 10.1152/jn.00904.2017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Multisite optical recording has revealed that the neural excitation wave induced by a sensory stimulation begins at a focus and propagates in the cortex. This wave is considered to be important for computation in the sensory cortex, particularly the integration of sensory information; however, the nature of this wave remains largely unknown. In the present study, we examined the interaction between two waves in the rat sensory cortex induced by hindlimb and forelimb stimuli with different interstimulus intervals. We classified the resultant patterns as follows: 1) the collision of two waves, 2) the hindlimb response being evoked while the forelimb-induced wave is passing the hindlimb focus, and 3) the hindlimb response being evoked after the forelimb-induced wave has passed the hindlimb focus. In pattern 1, the two waves fused into a single wave, but the propagation pattern differed from that predicted by the superimposition of two singly induced propagation courses. In pattern 2, the state of the interaction between the two waves varied depending on the phase of optical signals constituting the forelimb-induced wave around the hindlimb focus. Although no hindlimb-induced wave was observed in the rising phase, the propagating velocity of the forelimb-induced wave increased. At the peak, neither the hindlimb-induced response nor a modulatory effect on the forelimb-induced wave was detected. In pattern 3, the hindlimb-induced wave showed a reduced amplitude and spatial extent. These results indicate that the state of the interaction between waves was strongly influenced by the relative timing of sensory inputs. NEW & NOTEWORTHY Sensory stimulation-induced cortical excitation propagates as a wave and spreads over a wide area of the sensory cortex. To elucidate the characteristics of this relatively unknown phenomenon, we examined the interaction between two individually induced waves in the somatosensory cortex. Either the waves collided or the preceding wave affected the emergence of the following one. Our results indicate that the state of the interaction was strongly influenced by the relative timing of sensory inputs.
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Affiliation(s)
- Noriyuki Hama
- Department of Neural and Muscular Physiology, Shimane University School of Medicine, Izumo, Shimane, Japan
| | - Minako Kawai
- Department of Neural and Muscular Physiology, Shimane University School of Medicine, Izumo, Shimane, Japan
| | - Shin-Ichi Ito
- Department of Neural and Muscular Physiology, Shimane University School of Medicine, Izumo, Shimane, Japan
| | - Akihiko Hirota
- Department of Neural and Muscular Physiology, Shimane University School of Medicine, Izumo, Shimane, Japan
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13
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Humanes-Valera D, Foffani G, Alonso-Calviño E, Fernández-López E, Aguilar J. Dual Cortical Plasticity After Spinal Cord Injury. Cereb Cortex 2018; 27:2926-2940. [PMID: 27226441 DOI: 10.1093/cercor/bhw142] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
During cortical development, plasticity reflects the dynamic equilibrium between increasing and decreasing functional connectivity subserved by synaptic sprouting and pruning. After adult cortical deafferentation, plasticity seems to be dominated by increased functional connectivity, leading to the classical expansive reorganization from the intact to the deafferented cortex. In contrast, here we show a striking "decrease" in the fast cortical responses to high-intensity forepaw stimulation 1-3 months after complete thoracic spinal cord transection, as evident in both local field potentials and intracellular in vivo recordings. Importantly, this decrease in fast cortical responses co-exists with an "increase" in cortical activation over slower post-stimulus timescales, as measured by an increased forepaw-to-hindpaw propagation of stimulus-triggered cortical up-states, as well as by the enhanced slow sustained depolarization evoked by high-frequency forepaw stimuli in the deafferented hindpaw cortex. This coincidence of diminished fast cortical responses and enhanced slow cortical activation offers a dual perspective of adult cortical plasticity after spinal cord injury.
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Affiliation(s)
- Desire Humanes-Valera
- Hospital Nacional de Parapléjicos, Servicio de Salud de Castilla-La Mancha, 45071 Toledo, Spain.,Department of Systems Neuroscience, Institute of Physiology, Faculty of Medicine, Ruhr-University Bochum, D-44801 Bochum, Germany
| | - Guglielmo Foffani
- Hospital Nacional de Parapléjicos, Servicio de Salud de Castilla-La Mancha, 45071 Toledo, Spain.,CINAC, HM Puerta del Sur, Hospitales de Madrid, Móstoles, and CEU-San Pablo University, Madrid, Spain
| | - Elena Alonso-Calviño
- Hospital Nacional de Parapléjicos, Servicio de Salud de Castilla-La Mancha, 45071 Toledo, Spain
| | - Elena Fernández-López
- Hospital Nacional de Parapléjicos, Servicio de Salud de Castilla-La Mancha, 45071 Toledo, Spain
| | - Juan Aguilar
- Hospital Nacional de Parapléjicos, Servicio de Salud de Castilla-La Mancha, 45071 Toledo, Spain
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14
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Kjell J, Olson L. Rat models of spinal cord injury: from pathology to potential therapies. Dis Model Mech 2017; 9:1125-1137. [PMID: 27736748 PMCID: PMC5087825 DOI: 10.1242/dmm.025833] [Citation(s) in RCA: 226] [Impact Index Per Article: 32.3] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
A long-standing goal of spinal cord injury research is to develop effective spinal cord repair strategies for the clinic. Rat models of spinal cord injury provide an important mammalian model in which to evaluate treatment strategies and to understand the pathological basis of spinal cord injuries. These models have facilitated the development of robust tests for assessing the recovery of locomotor and sensory functions. Rat models have also allowed us to understand how neuronal circuitry changes following spinal cord injury and how recovery could be promoted by enhancing spontaneous regenerative mechanisms and by counteracting intrinsic inhibitory factors. Rat studies have also revealed possible routes to rescuing circuitry and cells in the acute stage of injury. Spatiotemporal and functional studies in these models highlight the therapeutic potential of manipulating inflammation, scarring and myelination. In addition, potential replacement therapies for spinal cord injury, including grafts and bridges, stem primarily from rat studies. Here, we discuss advantages and disadvantages of rat experimental spinal cord injury models and summarize knowledge gained from these models. We also discuss how an emerging understanding of different forms of injury, their pathology and degree of recovery has inspired numerous treatment strategies, some of which have led to clinical trials. Summary: In this Review, we discuss the advantages and disadvantages of the rat for studies of experimental spinal cord injury and summarize the knowledge gained from such studies.
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Affiliation(s)
- Jacob Kjell
- Department of Physiological Genomics, Ludwig-Maximilians-Universität München, Munich 80336, Germany
| | - Lars Olson
- Department of Neuroscience, Karolinska Institutet, Stockholm 171 77, Sweden
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15
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Boussida S, Traoré AS, Durif F. Mapping of the brain hemodynamic responses to sensorimotor stimulation in a rodent model: A BOLD fMRI study. PLoS One 2017; 12:e0176512. [PMID: 28441420 PMCID: PMC5404844 DOI: 10.1371/journal.pone.0176512] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Accepted: 04/12/2017] [Indexed: 12/02/2022] Open
Abstract
Blood Oxygenation Level Dependent functional MRI (BOLD fMRI) during electrical paw stimulation has been widely used in studies aimed at the understanding of the somatosensory network in rats. However, despite the well-established anatomical connections between cortical and subcortical structures of the sensorimotor system, most of these functional studies have been concentrated on the cortical effects of sensory electrical stimulation. BOLD fMRI study of the integration of a sensorimotor input across the sensorimotor network requires an appropriate methodology to elicit functional activation in cortical and subcortical areas owing to the regional differences in both neuronal and vascular architectures between these brain regions. Here, using a combination of low level anesthesia, long pulse duration of the electrical stimulation along with improved spatial and temporal signal to noise ratios, we provide a functional description of the main cortical and subcortical structures of the sensorimotor rat brain. With this calibrated fMRI protocol, unilateral non-noxious sensorimotor electrical hindpaw stimulation resulted in robust positive activations in the contralateral sensorimotor cortex and bilaterally in the sensorimotor thalamus nuclei, whereas negative activations were observed bilaterally in the dorsolateral caudate-putamen. These results demonstrate that, once the experimental setup allowing necessary spatial and temporal signal to noise ratios is reached, hemodynamic changes related to neuronal activity, as preserved by the combination of a soft anesthesia with a soft muscle relaxation, can be measured within the sensorimotor network. Moreover, the observed responses suggest that increasing pulse duration of the electrical stimulus adds a proprioceptive component to the sensory input that activates sensorimotor network in the brain, and that these activation patterns are similar to those induced by digits paw’s movements. These findings may find application in fMRI studies of sensorimotor disorders within cortico-basal network in rodents.
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16
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Eippert F, Kong Y, Jenkinson M, Tracey I, Brooks JCW. Denoising spinal cord fMRI data: Approaches to acquisition and analysis. Neuroimage 2016; 154:255-266. [PMID: 27693613 DOI: 10.1016/j.neuroimage.2016.09.065] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 09/23/2016] [Accepted: 09/27/2016] [Indexed: 01/11/2023] Open
Abstract
Functional magnetic resonance imaging (fMRI) of the human spinal cord is a difficult endeavour due to the cord's small cross-sectional diameter, signal drop-out as well as image distortion due to magnetic field inhomogeneity, and the confounding influence of physiological noise from cardiac and respiratory sources. Nevertheless, there is great interest in spinal fMRI due to the spinal cord's role as the principal sensorimotor interface between the brain and the body and its involvement in a variety of sensory and motor pathologies. In this review, we give an overview of the various methods that have been used to address the technical challenges in spinal fMRI, with a focus on reducing the impact of physiological noise. We start out by describing acquisition methods that have been tailored to the special needs of spinal fMRI and aim to increase the signal-to-noise ratio and reduce distortion in obtained images. Following this, we concentrate on image processing and analysis approaches that address the detrimental effects of noise. While these include variations of standard pre-processing methods such as motion correction and spatial filtering, the main focus lies on denoising techniques that can be applied to task-based as well as resting-state data sets. We review both model-based approaches that rely on externally acquired respiratory and cardiac signals as well as data-driven approaches that estimate and correct for noise using the data themselves. We conclude with an outlook on techniques that have been successfully applied for noise reduction in brain imaging and whose use might be beneficial for fMRI of the human spinal cord.
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Affiliation(s)
- Falk Eippert
- Oxford Centre for Functional Magnetic Resonance Imaging of the Brain, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Yazhuo Kong
- Oxford Centre for Functional Magnetic Resonance Imaging of the Brain, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Mark Jenkinson
- Oxford Centre for Functional Magnetic Resonance Imaging of the Brain, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Irene Tracey
- Oxford Centre for Functional Magnetic Resonance Imaging of the Brain, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
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17
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Weber KA, Chen Y, Wang X, Kahnt T, Parrish TB. Functional magnetic resonance imaging of the cervical spinal cord during thermal stimulation across consecutive runs. Neuroimage 2016; 143:267-279. [PMID: 27616641 DOI: 10.1016/j.neuroimage.2016.09.015] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 08/19/2016] [Accepted: 09/08/2016] [Indexed: 12/29/2022] Open
Abstract
The spinal cord is the first site of nociceptive processing in the central nervous system and has a role in the development and perpetuation of clinical pain states. Advancements in functional magnetic resonance imaging are providing a means to non-invasively measure spinal cord function, and functional magnetic resonance imaging may provide an objective method to study spinal cord nociceptive processing in humans. In this study, we tested the validity and reliability of functional magnetic resonance imaging using a selective field-of-view gradient-echo echo-planar-imaging sequence to detect activity induced blood oxygenation level-dependent signal changes in the cervical spinal cord of healthy volunteers during warm and painful thermal stimulation across consecutive runs. At the group and subject level, the activity was localized more to the dorsal hemicord, the spatial extent and magnitude of the activity was greater for the painful stimulus than the warm stimulus, and the spatial extent and magnitude of the activity exceeded that of a control analysis. Furthermore, the spatial extent of the activity for the painful stimuli increased across the runs likely reflecting sensitization. Overall, the spatial localization of the activity varied considerably across the runs, but despite this variability, a machine-learning algorithm was able to successfully decode the stimuli in the spinal cord based on the distributed pattern of the activity. In conclusion, we were able to successfully detect and characterize cervical spinal cord activity during thermal stimulation at the group and subject level.
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Affiliation(s)
- Kenneth A Weber
- Department of Radiology, Northwestern University, 737 North Michigan Avenue, Suite 1600, Chicago, IL 60611, USA.
| | - Yufen Chen
- Department of Radiology, Northwestern University, 737 North Michigan Avenue, Suite 1600, Chicago, IL 60611, USA
| | - Xue Wang
- Department of Radiology, Northwestern University, 737 North Michigan Avenue, Suite 1600, Chicago, IL 60611, USA
| | - Thorsten Kahnt
- Department of Neurology, Northwestern University, 303 East Chicago Avenue, Ward 13-006, Chicago, IL 60611, USA
| | - Todd B Parrish
- Department of Radiology, Northwestern University, 737 North Michigan Avenue, Suite 1600, Chicago, IL 60611, USA
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18
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Increased responses in the somatosensory thalamus immediately after spinal cord injury. Neurobiol Dis 2016; 87:39-49. [DOI: 10.1016/j.nbd.2015.12.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Revised: 11/26/2015] [Accepted: 12/14/2015] [Indexed: 11/24/2022] Open
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19
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[Imaging techniques and pain]. Schmerz 2015; 29:539-43. [PMID: 26351124 DOI: 10.1007/s00482-015-0053-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Over the last 15 years, functional brain imaging techniques have provided critical insights into cortical, subcortical and even spinal mechanisms involved in pain perception and pain modulation in humans. The pivotal contribution of brain imaging studies conducted in Germany have thereby been internationally acknowledged. One of the key challenges for the next decade is to shift the focus from studies in healthy volunteers to different clinical populations suffering from chronic pain to characterize CNS mechanisms, as well as neurobiological predictors and resilience factors of pain chronification. Ultimately, the knowledge gained by this work may help identify individual or syndrome-specific CNS changes as biomarkers to make therapeutic decisions.
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20
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BOLD fMRI of C-Fiber Mediated Nociceptive Processing in Mouse Brain in Response to Thermal Stimulation of the Forepaws. PLoS One 2015; 10:e0126513. [PMID: 25950440 PMCID: PMC4423852 DOI: 10.1371/journal.pone.0126513] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 03/17/2015] [Indexed: 11/30/2022] Open
Abstract
Functional magnetic resonance imaging (fMRI) in rodents enables non-invasive studies of brain function in response to peripheral input or at rest. In this study we describe a thermal stimulation paradigm using infrared laser diodes to apply noxious heat to the forepaw of mice in order to study nociceptive processing. Stimulation at 45 and 46°C led to robust BOLD signal changes in various brain structures including the somatosensory cortices and the thalamus. The BOLD signal amplitude scaled with the temperature applied but not with the area irradiated by the laser beam. To demonstrate the specificity of the paradigm for assessing nociceptive signaling we administered the quaternary lidocaine derivative QX-314 to the forepaws, which due to its positive charge cannot readily cross biological membranes. However, upon activation of TRPV1 channels following the administration of capsaicin the BOLD signal was largely abolished, indicative of a selective block of the C-fiber nociceptors due to QX-314 having entered the cells via the now open TRPV1 channels. This demonstrates that the cerebral BOLD response to thermal noxious paw stimulation is specifically mediated by C-fibers.
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21
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Yagüe J, Humanes-Valera D, Aguilar J, Foffani G. Functional reorganization of the forepaw cortical representation immediately after thoracic spinal cord hemisection in rats. Exp Neurol 2014; 257:19-24. [DOI: 10.1016/j.expneurol.2014.03.015] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Revised: 03/07/2014] [Accepted: 03/19/2014] [Indexed: 11/28/2022]
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22
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Fratini M, Moraschi M, Maraviglia B, Giove F. On the impact of physiological noise in spinal cord functional MRI. J Magn Reson Imaging 2013; 40:770-7. [PMID: 24925698 DOI: 10.1002/jmri.24467] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Accepted: 09/11/2013] [Indexed: 01/09/2023] Open
Abstract
Functional magnetic resonance imaging (fMRI) techniques are widely exploited for the study of brain activation. In recent years, similar approaches have been attempted for the study of spinal cord function; however, obtaining good functional images of spinal cord still represents a technical and scientific challenge. Some of the main limiting factors can be classified under the broad category of "physiological noise," and are related to 1) the cerebrospinal fluid (CSF) flux in the subarachnoid space surrounding the spinal cord; 2) the cord motion itself; and 3) the small area of the cord, which makes it critical to have a high image resolution. In addition, the different magnetic susceptibility properties of tissues surrounding the spinal cord reduce the local homogeneity of the static magnetic field, causing image distortion, reduction of the effective resolution, and signal loss, all effects that are modulated by motion. For these reasons, a number of methods have been developed for the purpose of denoising spinal cord fMRI time series. In this work, after a short introduction on the relevant features of the spinal cord anatomy, we review the main sources of physiological noise in spinal cord fMRI and discuss the main approaches useful for its mitigation.
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Affiliation(s)
- Michela Fratini
- MARBILab - Museo storico della fisica e Centro di studi e ricerche Enrico Fermi, Roma, Italy; Dipartimento di Fisica, Sapienza Universita' di Roma, Roma, Italy
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23
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Sydekum E, Ghosh A, Gullo M, Baltes C, Schwab M, Rudin M. Rapid functional reorganization of the forelimb cortical representation after thoracic spinal cord injury in adult rats. Neuroimage 2013; 87:72-9. [PMID: 24185021 DOI: 10.1016/j.neuroimage.2013.10.045] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 09/30/2013] [Accepted: 10/21/2013] [Indexed: 11/28/2022] Open
Abstract
Thoracic spinal cord injured rats rely largely on forelimbs to walk, as their hindlimbs are dysfunctional. This increased limb use is accompanied by expansion of the cortical forelimb sensory representation. It is unclear how quickly the representational changes occur and whether they are at all related to the behavioral adaptation. Using blood oxygenation level dependent functional mangetic resonance imaging (BOLD-fMRI) we show that major plastic changes of the somato-sensory map can occur as early as one day after injury. The extent of map increase was variable between animals, and some animals showed a reduction in map size. However, at three or seven days after injury a significant enhancement of the forelimb representation was evident in all the animals. In a behavioral test for precise limb control, crossing of a horizontal ladder, the injured rats relied almost entirely on their forelimbs; they initially made more mistakes than at 7 days post injury. Remarkably, in the individual animals the behavioral performance seen at seven days was proportional to the physiological change present at one day after injury. The rapid increase in cortical representation of the injury-spared body part may provide the additional neural substrate necessary for high level behavioral adaptation.
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Affiliation(s)
- Esther Sydekum
- Institute for Biomedical Engineering, University of Zurich, Switzerland; ETH Zurich, Switzerland
| | - Arko Ghosh
- Institute of Neuroinformatics, University of Zurich, Switzerland; Center for Neuroscience Zurich, University of Zurich and ETH Zurich, Switzerland; Institute of Cognitive Neuroscience, University College London, UK; ETH Zurich, Switzerland.
| | - Miriam Gullo
- Brain Research Institute, University of Zurich, Switzerland; ETH Zurich, Switzerland
| | - Christof Baltes
- Institute for Biomedical Engineering, University of Zurich, Switzerland; ETH Zurich, Switzerland
| | - Martin Schwab
- Center for Neuroscience Zurich, University of Zurich and ETH Zurich, Switzerland; Brain Research Institute, University of Zurich, Switzerland; ETH Zurich, Switzerland
| | - Markus Rudin
- Institute for Biomedical Engineering, University of Zurich, Switzerland; Center for Neuroscience Zurich, University of Zurich and ETH Zurich, Switzerland; Institute for Pharmacology and Toxicology, University of Zurich, Switzerland; ETH Zurich, Switzerland.
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24
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Zhao F, Williams M, Bowlby M, Houghton A, Hargreaves R, Evelhoch J, Williams DS. Qualification of fMRI as a biomarker for pain in anesthetized rats by comparison with behavioral response in conscious rats. Neuroimage 2013; 84:724-32. [PMID: 24064074 DOI: 10.1016/j.neuroimage.2013.09.036] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Revised: 09/07/2013] [Accepted: 09/13/2013] [Indexed: 10/26/2022] Open
Abstract
fMRI can objectively measure pain-related neural activities in humans and animals, providing a valuable tool for studying the mechanisms of nociception and for developing new analgesics. However, due to its extreme sensitivity to subject motion, pain fMRI studies are performed in animals that are immobilized, typically with anesthesia. Since anesthesia could confound the nociceptive processes, it is unknown how well nociceptive-related neural activities measured by fMRI in anesthetized animals correlate with nociceptive behaviors in conscious animals. The threshold to vocalization (VT) in response to an increasing noxious electrical stimulus (NES) was implemented in conscious rats as a behavioral measure of nociception. The antinociceptive effect of systemic (intravenous infusion) lidocaine on NES-induced fMRI signals in anesthetized rats was compared with the corresponding VT in conscious rats. Lidocaine infusion increased VT and suppressed the NES-induced fMRI signals in most activated brain regions. The temporal characteristics of the nociception signal by fMRI and by VT in response to lidocaine infusion were highly correlated with each other, and with the pharmacokinetics (PK) of lidocaine. These results indicate that the fMRI activations in these regions may be used as biomarkers of acute nociception in anesthetized rats. Interestingly, systemic lidocaine had no effect on NES-induced fMRI activations in the primary somatosensory cortex (S1), a result that warrants further investigation.
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25
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Humanes-Valera D, Aguilar J, Foffani G. Reorganization of the intact somatosensory cortex immediately after spinal cord injury. PLoS One 2013; 8:e69655. [PMID: 23922771 PMCID: PMC3726757 DOI: 10.1371/journal.pone.0069655] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Accepted: 06/14/2013] [Indexed: 02/06/2023] Open
Abstract
Sensory deafferentation produces extensive reorganization of the corresponding deafferented cortex. Little is known, however, about the role of the adjacent intact cortex in this reorganization. Here we show that a complete thoracic transection of the spinal cord immediately increases the responses of the intact forepaw cortex to forepaw stimuli (above the level of the lesion) in anesthetized rats. These increased forepaw responses were independent of the global changes in cortical state induced by the spinal cord transection described in our previous work (Aguilar et al., J Neurosci 2010), as the responses increased both when the cortex was in a silent state (down-state) or in an active state (up-state). The increased responses in the intact forepaw cortex correlated with increased responses in the deafferented hindpaw cortex, suggesting that they could represent different points of view of the same immediate state-independent functional reorganization of the primary somatosensory cortex after spinal cord injury. Collectively, the results of the present study and of our previous study suggest that both state-dependent and state-independent mechanisms can jointly contribute to cortical reorganization immediately after spinal cord injury.
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Affiliation(s)
- Desire Humanes-Valera
- Hospital Nacional de Parapléjicos, Servicio de Salud de Castilla-La Mancha, Toledo, Spain
| | - Juan Aguilar
- Hospital Nacional de Parapléjicos, Servicio de Salud de Castilla-La Mancha, Toledo, Spain
- * E-mail: (JA); (GF)
| | - Guglielmo Foffani
- Hospital Nacional de Parapléjicos, Servicio de Salud de Castilla-La Mancha, Toledo, Spain
- * E-mail: (JA); (GF)
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26
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Murray D, Stoessl AJ. Mechanisms and therapeutic implications of the placebo effect in neurological and psychiatric conditions. Pharmacol Ther 2013; 140:306-18. [PMID: 23880289 DOI: 10.1016/j.pharmthera.2013.07.009] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Accepted: 07/09/2013] [Indexed: 12/19/2022]
Abstract
The power of a placebo to effect clinically meaningful neurobiological change comparable to pharmacological therapies has been demonstrated, although the mechanisms are not fully understood. Predicting placebo responsiveness has only recently received more attention, but psychological disposition, contextual and biological factors are now known to dramatically affect a person's susceptibility to the placebo effect. The placebo effect depends upon expectancies that can be modified in a number of ways, including conditioning through explicit or implicit learned associations. Based on the dopaminergic response to anticipation of benefit in Parkinson's disease, it was suggested that the placebo effect can be seen as analogous to the expectation of reward. Dopaminergic pathways have since been implicated in the placebo response in pain and depression. Additionally, endogenous opioid release is known to mediate many forms of placebo analgesia. We provide an overview of the mechanisms and the therapeutic implications of the placebo effect in neurological and psychiatric conditions. We include evidence for detrimental effects arising from seemingly inert interventions, termed the 'nocebo effect.' Neuroimaging has critically advanced the study of the placebo effect and provides some of the strongest evidence for the mechanisms of this phenomenon prevalent across an array of human health-related circumstances. This review specifically focuses on mechanisms of the placebo effect in the three conditions that have most significantly demonstrated this effect and for which a plausible physiological basis can be identified: pain, PD and depression. Other neurological and psychiatric diseases reviewed include multiple sclerosis, Huntington's disease, Alzheimer's disease, schizophrenia and epilepsy.
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Affiliation(s)
- Danielle Murray
- Pacific Parkinson's Research Centre and Department of Medicine, Division of Neurology, University of British Columbia & Vancouver Coastal Health, Canada
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Nardone R, Höller Y, Brigo F, Seidl M, Christova M, Bergmann J, Golaszewski S, Trinka E. Functional brain reorganization after spinal cord injury: Systematic review of animal and human studies. Brain Res 2013; 1504:58-73. [DOI: 10.1016/j.brainres.2012.12.034] [Citation(s) in RCA: 121] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2012] [Revised: 11/26/2012] [Accepted: 12/24/2012] [Indexed: 12/18/2022]
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Cortright DN, Matson DJ, Broom DC. New frontiers in assessing pain and analgesia in laboratory animals. Expert Opin Drug Discov 2013; 3:1099-108. [PMID: 23506182 DOI: 10.1517/17460441.3.9.1099] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
BACKGROUND Translating promising analgesic compounds into reliable pain therapeutics in humans is made particularly challenging by the difficulty in measuring the pain quantitatively. This problem is manifest not only in clinical settings in which patient pain assessments involve mostly subjective measures but also in preclinical settings wherein laboratory animals, most commonly rodents, are typically evaluated in stimulus-evoked response tests. OBJECTIVE Given the limitations of traditional pain tests, we sought out new approaches to measure pain, and analgesia, in laboratory animals. METHODS We reviewed the peer reviewed literature to identify pain tests that could be utilized in preclinical settings to understand the effects of new and established analgesics. RESULTS/CONCLUSIONS The tests identified include weight bearing differential, suppression of feeding, reduction in locomotor activity, gait analysis, conditioning models and functional MRI. Although the pharmacology of known and new analgesics has not been broadly established in these models, they hold the promise of better predictive utility for the discovery of pain relievers.
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Bellistri E, Aguilar J, Brotons-Mas JR, Foffani G, de la Prida LM. Basic properties of somatosensory-evoked responses in the dorsal hippocampus of the rat. J Physiol 2013; 591:2667-86. [PMID: 23420661 DOI: 10.1113/jphysiol.2013.251892] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The hippocampus is a pivotal structure for episodic memory function. This ability relies on the possibility of integrating different features of sensory stimuli with the spatio-temporal context in which they occur. While recent studies now suggest that somatosensory information is already processed by the hippocampus, the basic mechanisms still remain unexplored. Here, we used electrical stimulation of the paws, the whisker pad or the medial lemniscus to probe the somatosensory pathway to the hippocampus in the anaesthetized rat, and multisite electrodes, in combination with tetrode and intracellular recordings, to look at the properties of somatosensory hippocampal responses. We found that peripheral and lemniscal stimulation elicited small local field potential responses in the dorsal hippocampus about 35-40 ms post-stimulus. Current source density analysis established the local nature of these responses, revealing associated synaptic sinks that were consistently confined to the molecular layer (ML) of the dentate gyrus (DG), with less regular activation of the CA1 stratum lacunosum moleculare (SLM). A delayed (40-45 ms), potentially active, current source that outlasted the SLM sink was present in about 50% cases around the CA1 pyramidal cell layer. Somatosensory stimulation resulted in multi-unit firing increases in the majority of DG responses (79%), whereas multi-unit firing suppression was observed in the majority of CA1 responses (62%). Tetrode and intracellular recordings of individual cells confirmed different firing modulation in the DG and the CA1 region, and verified the active nature of both the early ML sink and delayed somatic CA1 source. Hippocampal responses to somatosensory stimuli were dependent on fluctuations in the strength and composition of synaptic inputs due to changes of the ongoing local (hippocampal) and distant (cortical) state. We conclude that somatosensory signals reach the hippocampus mainly from layer II entorhinal cortex to directly discharge DG granule cells, while a different predominantly inhibitory process takes place in CA1, further controlling the hippocampal output. Therefore, our data reveal a distinct organization of somatosensory-related extra-hippocampal inputs converging onto DG and CA1.
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Affiliation(s)
- Elisa Bellistri
- Instituto Cajal CSIC, Neurobiología-Investigación, Ave Doctor Arce 37, Madrid 28002, Spain
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30
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Aizawa-Kohama M, Endo T, Kitada M, Wakao S, Sumiyoshi A, Matsuse D, Kuroda Y, Morita T, Riera JJ, Kawashima R, Tominaga T, Dezawa M. Transplantation of bone marrow stromal cell-derived neural precursor cells ameliorates deficits in a rat model of complete spinal cord transection. Cell Transplant 2012; 22:1613-25. [PMID: 23127893 DOI: 10.3727/096368912x658791] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
After severe spinal cord injury, spontaneous functional recovery is limited. Numerous studies have demonstrated cell transplantation as a reliable therapeutic approach. However, it remains unknown whether grafted neuronal cells could replace lost neurons and reconstruct neuronal networks in the injured spinal cord. To address this issue, we transplanted bone marrow stromal cell-derived neural progenitor cells (BM-NPCs) in a rat model of complete spinal cord transection 9 days after the injury. BM-NPCs were induced from bone marrow stromal cells (BMSCs) by gene transfer of the Notch-1 intracellular domain followed by culturing in the neurosphere method. As reported previously, BM-NPCs differentiated into neuronal cells in a highly selective manner in vitro. We assessed hind limb movements of the animals weekly for 7 weeks to monitor functional recovery after local injection of BM-NPCs to the transected site. To test the sensory recovery, we performed functional magnetic resonance imaging (fMRI) using electrical stimulation of the hind limbs. In the injured spinal cord, transplanted BM-NPCs were confirmed to express neuronal markers 7 weeks following the transplantation. Grafted cells successfully extended neurites beyond the transected portion of the spinal cord. Adjacent localization of synaptophysin and PSD-95 in the transplanted cells suggested synaptic formations. These results indicated survival and successful differentiation of BM-NPCs in the severely injured spinal cord. Importantly, rats that received BM-NPCs demonstrated significant motor recovery when compared to the vehicle injection group. Volumes of the fMRI signals in somatosensory cortex were larger in the BM-NPC-grafted animals. However, neuronal activity was diverse and not confined to the original hind limb territory in the somatosensory cortex. Therefore, reconstruction of neuronal networks was not clearly confirmed. Our results indicated BM-NPCs as an effective method to deliver neuronal lineage cells in a severely injured spinal cord. However, reestablishment of neuronal networks in completed transected spinal cord was still a challenging task.
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Affiliation(s)
- Misaki Aizawa-Kohama
- Department of Stem Cell Biology and Histology, Tohoku University Graduate School of Medicine, Sendai, Japan
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Fujiyoshi K, Konomi T, Yamada M, Hikishima K, Tsuji O, Komaki Y, Momoshima S, Toyama Y, Nakamura M, Okano H. Diffusion tensor imaging and tractography of the spinal cord: from experimental studies to clinical application. Exp Neurol 2012; 242:74-82. [PMID: 22868199 DOI: 10.1016/j.expneurol.2012.07.015] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2011] [Revised: 06/21/2012] [Accepted: 07/24/2012] [Indexed: 02/08/2023]
Abstract
Diffusion-weighted magnetic resonance imaging provides detailed information about biological structures. In particular, diffusion tensor imaging and diffusion tensor tractography (DTT) are powerful tools for evaluating white matter fibers in the central nervous system. We previously established a reproducible spinal cord injury model in adult common marmosets and showed that DTT could be used to trace the neural tracts in the intact and injured spinal cord of these animals in vivo. Recently, many reports using DTT to analyze the spinal cord area have been published. Based on the findings from our experimental studies, we are now routinely performing DTT of the human spinal cord in the clinic. In this review we outline the basic principles of DTT, and describe the characteristics, limitations, and future uses of DTT to examine the spinal cord.
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Affiliation(s)
- Kanehiro Fujiyoshi
- Department of Orthopaedic Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjuku, Tokyo 160-8582, Japan
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Imaging the spatio-temporal dynamics of supragranular activity in the rat somatosensory cortex in response to stimulation of the paws. PLoS One 2012; 7:e40174. [PMID: 22829873 PMCID: PMC3400596 DOI: 10.1371/journal.pone.0040174] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Accepted: 06/03/2012] [Indexed: 11/25/2022] Open
Abstract
We employed voltage-sensitive dye (VSD) imaging to investigate the spatio-temporal dynamics of the responses of the supragranular somatosensory cortex to stimulation of the four paws in urethane-anesthetized rats. We obtained the following main results. (1) Stimulation of the contralateral forepaw evoked VSD responses with greater amplitude and smaller latency than stimulation of the contralateral hindpaw, and ipsilateral VSD responses had a lower amplitude and greater latency than contralateral responses. (2) While the contralateral stimulation initially activated only one focus, the ipsilateral stimulation initially activated two foci: one focus was typically medial to the focus activated by contralateral stimulation and was stereotaxically localized in the motor cortex; the other focus was typically posterior to the focus activated by contralateral stimulation and was stereotaxically localized in the somatosensory cortex. (3) Forepaw and hindpaw somatosensory stimuli activated large areas of the sensorimotor cortex, well beyond the forepaw and hindpaw somatosensory areas of classical somatotopic maps, and forepaw stimuli activated larger cortical areas with greater activation velocity than hindpaw stimuli. (4) Stimulation of the forepaw and hindpaw evoked different cortical activation dynamics: forepaw responses displayed a clear medial directionality, whereas hindpaw responses were much more uniform in all directions. In conclusion, this work offers a complete spatio-temporal map of the supragranular VSD cortical activation in response to stimulation of the paws, showing important somatotopic differences between contralateral and ipsilateral maps as well as differences in the spatio-temporal activation dynamics in response to forepaw and hindpaw stimuli.
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Reduction of physiological noise with independent component analysis improves the detection of nociceptive responses with fMRI of the human spinal cord. Neuroimage 2012; 63:245-52. [PMID: 22776463 DOI: 10.1016/j.neuroimage.2012.06.057] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Revised: 06/22/2012] [Accepted: 06/23/2012] [Indexed: 11/20/2022] Open
Abstract
The evaluation of spinal cord neuronal activity in humans with functional magnetic resonance imaging (fMRI) is technically challenging. Major difficulties arise from cardiac and respiratory movement artifacts that constitute significant sources of noise. In this paper we assessed the Correction of Structured noise using spatial Independent Component Analysis (CORSICA). FMRI data of the cervical spinal cord were acquired in 14 healthy subjects using gradient-echo EPI. Nociceptive electrical stimuli were applied to the thumb. Additional data with short TR (250 ms, to prevent aliasing) were acquired to generate a spatial map of physiological noise derived from Independent Component Analysis (ICA). Physiological noise was subsequently removed from the long-TR data after selecting independent components based on the generated noise map. Stimulus-evoked responses were analyzed using the general linear model, with and without CORSICA and with a regressor generated from the cerebrospinal fluid region. Results showed higher sensitivity to detect stimulus-related activation in the targeted dorsal segment of the cord after CORSICA. Furthermore, fewer voxels showed stimulus-related signal changes in the CSF and outside the spinal region, suggesting an increase in specificity. ICA can be used to effectively reduce physiological noise in spinal cord fMRI time series.
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34
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Bosshard SC, Grandjean J, Schroeter A, Baltes C, Zeilhofer HU, Rudin M. Hyperalgesia by low doses of the local anesthetic lidocaine involves cannabinoid signaling: An fMRI study in mice. Pain 2012; 153:1450-1458. [DOI: 10.1016/j.pain.2012.04.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Revised: 03/29/2012] [Accepted: 04/02/2012] [Indexed: 12/17/2022]
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Stimulus site and modality dependence of functional activity within the human spinal cord. J Neurosci 2012; 32:6231-9. [PMID: 22553029 DOI: 10.1523/jneurosci.2543-11.2012] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Chronic pain is thought to arise because of maladaptive changes occurring within the peripheral nervous system and CNS. The transition from acute to chronic pain is known to involve the spinal cord (Woolf and Salter, 2000). Therefore, to investigate altered human spinal cord function and translate results obtained from other species, a noninvasive neuroimaging technique is desirable. We have investigated the functional response in the cervical spinal cord of 18 healthy human subjects (aged 22-40 years) to noxious thermal and non-noxious tactile stimulation of the left and right forearms. Physiological noise, which is a significant source of signal variability in the spinal cord, was accounted for in the general linear model. Group analysis, performed using a mixed-effects model, revealed distinct regions of activity that were dependent on both the side and the type of stimulation. In particular, thermal stimulation on the medial aspect of the wrist produced activity within the C6/C5 segment ipsilateral to the side of stimulation. Similar to data recorded in animals (Fitzgerald, 1982), painful thermal stimuli produced increased ipsilateral and decreased contralateral blood flow, which may reflect, respectively, excitatory and inhibitory processes. Nonpainful punctate stimulation of the thenar eminence provoked more diffuse activity but was still ipsilateral to the side of stimulation. These results present the first noninvasive evidence for a lateralized response to noxious and non-noxious stimuli in the human spinal cord. The development of these techniques opens the path to understanding, at a subject-specific level, central sensitization processes that contribute to chronic pain states.
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36
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Assessment of physiological noise modelling methods for functional imaging of the spinal cord. Neuroimage 2012; 60:1538-49. [DOI: 10.1016/j.neuroimage.2011.11.077] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Revised: 10/26/2011] [Accepted: 11/25/2011] [Indexed: 11/22/2022] Open
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Aguilar J, Pulecchi F, Dilena R, Oliviero A, Priori A, Foffani G. Spinal direct current stimulation modulates the activity of gracile nucleus and primary somatosensory cortex in anaesthetized rats. J Physiol 2011; 589:4981-96. [PMID: 21825031 DOI: 10.1113/jphysiol.2011.214189] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Afferent somatosensory activity from the spinal cord has a profound impact on the activity of the brain. Here we investigated the effects of spinal stimulation using direct current, delivered at the thoracic level, on the spontaneous activity and on the somatosensory evoked potentials of the gracile nucleus, which is the main entry point for hindpaw somatosensory signals reaching the brain from the dorsal columns, and of the primary somatosensory cortex in anaesthetized rats. Anodal spinal direct current stimulation (sDCS) increased the spontaneous activity and decreased the amplitude of evoked responses in the gracile nucleus, whereas cathodal sDCS produced the opposite effects. At the level of the primary somatosensory cortex, the changes in spontaneous activity induced by sDCS were consistent with the effects observed in the gracile nucleus, but the changes in cortical evoked responses were more variable and state dependent. Therefore, sDCS can modulate in a polarity-specific manner the supraspinal activity of the somatosensory system, offering a versatile bottom-up neuromodulation technique that could potentially be useful in a number of clinical applications.
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Affiliation(s)
- J Aguilar
- Hospital Nacional de Parapléjicos, SESCAM, Toledo, Spain.
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38
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Abstract
Sensory and motor representations embedded in topographic cortical maps are use-dependent, dynamically maintained, and self-organizing functional mosaics that constitute idiosyncratic entities involved in perceptual and motor learning abilities. Studies of cortical map plasticity have substantiated the view that local reorganization of sensory and motor areas has great significance in recovery of function following brain damage or spinal cord injury. In addition, the transfer of function to distributed cortical areas and subcortical structures represents an adaptive strategy for functional compensation. There is a growing consensus that subject-environment interactions, by continuously refining the canvas of synaptic connectivity and reshaping the anatomical and functional architecture of neural circuits, promote adaptive behavior throughout life. Taking advantage of use-dependent neural plasticity, early initiated rehabilitative procedures improve the potential for recovery.
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Affiliation(s)
- Christian Xerri
- Integrative and Adaptive Neurosciences, University of Provence/CNRS, Marseille, France
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39
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Abstract
Functional brain imaging techniques allow to noninvasively visualize neuronal activity and associated metabolic consequences. In combination with elegant experimental paradigms in both healthy volunteers and, increasingly, in patients, functional brain imaging has led to a vast accumulation of knowledge concerning the CNS mechanisms involved in pain perception and pain modulation in humans. The so-called "pain matrix" represents a dynamic network of cortical and subcortical brain regions regularly activated by acute pain. This includes the somatosensory cortices (SI, SII), insular cortex, the cingulate cortex, prefrontal areas, amygdala, thalamus, brainstem and cerebellum. The subjective perception of pain is substantially influenced by context-dependent intracortical modulations and the descending pain modulatory system. This system includes cingulo-frontal brain areas together with specific brainstem nuclei that can exert control over nociceptive input at the level of the dorsal horn of the spinal cord. Recent studies support the view that a dysfunctional interaction between the ascending and descending pain system may contribute to the development or maintenance of chronic pain states. Here we provide an overview of the principles, applications, key findings and recent advances of functional imaging in pain research.
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Affiliation(s)
- K Somborski
- Institut für Systemische Neurowissenschaften, Universitätsklinikum Hamburg-Eppendorf, Martinistr. 52, 20246, Hamburg, Deutschland.
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40
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CNS activation maps in awake rats exposed to thermal stimuli to the dorsum of the hindpaw. Neuroimage 2011; 54:1355-66. [DOI: 10.1016/j.neuroimage.2010.08.056] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2010] [Revised: 08/19/2010] [Accepted: 08/21/2010] [Indexed: 01/08/2023] Open
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Yague JG, Foffani G, Aguilar J. Cortical hyperexcitability in response to preserved spinothalamic inputs immediately after spinal cord hemisection. Exp Neurol 2010; 227:252-63. [PMID: 21093438 DOI: 10.1016/j.expneurol.2010.11.011] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2010] [Accepted: 11/09/2010] [Indexed: 01/27/2023]
Abstract
Chronic injury of the main somatosensory pathways ascending along the spinal cord - the dorsal columns and the spinothalamic tract - can produce both changes in the organization of cortical somatotopic maps and neuropathic pain. Little is known, however, about the early neurophysiological changes occurring immediately after injury. We bilaterally recorded the neural activity of the hindpaw representation of the primary somatosensory cortex evoked by stimuli delivered to the hindpaws before and immediately after a thoracic spinal cord hemisection in anesthetized rats. This unilateral spinal cord injury allowed us to separately investigate the cortical effects of deafferenting the dorsal column (stimuli ipsilateral to the hemisection) or the spinothalamic tract (stimuli contralateral to the hemisection). The hemisection produced immediate bilateral changes in the cortical responses evoked by stimuli delivered to the hindpaw ipsilateral to the hemisection (deafferented dorsal column): an expected loss of classical short-latency cortical responses, accompanied by an unexpected appearance of long-latency activations. At the population level, these activations reflected a progressive stimulus-induced transition of the hindpaw somatosensory cortex from up-and-down states to a sustained activated state. At the single-cell level, these cortical activations resembled the "wind-up" typically observed - with the same type of stimuli - in the dorsal horn cells originating the spinothalamic tract. Virtually no changes were observed in the responses evoked by stimuli delivered to the hindpaw contralateral to the hemisection (deafferented spinothalamic tract). These results suggest that spinal cord hemisection immediately produces an abnormal hyperexcitability of the primary somatosensory cortex in response to preserved spinothalamic inputs from the hindpaw. This immediate cortical hyperexcitability could be important to understand the long-term development of cortical reorganization and neuropathic pain after incomplete spinal cord lesions.
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Affiliation(s)
- J G Yague
- Hospital Nacional de Parapléjicos, SESCAM, Toledo, Spain
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Bosshard SC, Baltes C, Wyss MT, Mueggler T, Weber B, Rudin M. Assessment of brain responses to innocuous and noxious electrical forepaw stimulation in mice using BOLD fMRI. Pain 2010; 151:655-663. [PMID: 20851520 DOI: 10.1016/j.pain.2010.08.025] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2009] [Revised: 08/04/2010] [Accepted: 08/17/2010] [Indexed: 10/19/2022]
Abstract
Functional magnetic resonance imaging (fMRI) using the blood oxygen level-dependent (BOLD) contrast was used to study sensory processing in the brain of isoflurane-anesthetized mice. The use of a cryogenic surface coil in a small animal 9.4T system provided the sensitivity required for detection and quantitative analysis of hemodynamic changes caused by neural activity in the mouse brain in response to electrical forepaw stimulation at different amplitudes. A gradient echo-echo planar imaging (GE-EPI) sequence was used to acquire five coronal brain slices of 0.5mm thickness. BOLD signal changes were observed in primary and secondary somatosensory cortices, the thalamus and the insular cortex, important regions involved in sensory and nociceptive processing. Activation was observed consistently bilateral despite unilateral stimulation of the forepaw. The temporal BOLD profile was segregated into two signal components with different temporal characteristics. The maximum BOLD amplitude of both signal components correlated strongly with the stimulation amplitude. Analysis of the dynamic behavior of the somatosensory 'fast' BOLD component revealed a decreasing signal decay rate constant k(off) with increasing maximum BOLD amplitude (and stimulation amplitude). This study demonstrates the feasibility of a robust BOLD fMRI protocol to study nociceptive processing in isoflurane-anesthetized mice. The reliability of the method allows for detailed analysis of the temporal BOLD profile and for investigation of somatosensory and noxious signal processing in the brain, which is attractive for characterizing genetically engineered mouse models.
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Affiliation(s)
- Simone C Bosshard
- Institute for Biomedical Engineering, University and ETH Zurich, Switzerland Institute of Pharmacology and Toxicology, University of Zurich, Switzerland PET Center, Department of Nuclear Medicine, University Hospital Zürich, Switzerland
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[Mechanisms of endogenous pain modulation illustrated by placebo analgesia : functional imaging findings]. Schmerz 2010; 24:122-9. [PMID: 20376600 DOI: 10.1007/s00482-010-0901-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Nociceptive information processing and related pain perception are subject to substantial pro- and antinociceptive modulation. Research on the involved circuitry and the implemented mechanisms is a major focus of contemporary neuroscientific studies in the field of pain and will provide new insights into the prevention and treatment of chronic pain states. Placebo analgesia is a powerful clinical example of the cognitive modulation of pain perception. In placebo analgesia the administration of an inert substance will produce an analgesic effect if the subject is convinced that the substance is a potent analgesic. Recent neuroimaging studies have started to characterize the neural circuitry supporting the placebo analgesic effect. The converging evidence from these studies supports the concept that during placebo analgesia cingulo-frontal regions interact with subcortical structures involved in endogenous antinociception to produce the placebo-induced reduction in pain perception. The subject's report of reduced pain during placebo analgesia coincides with decreased activity in the classic pain areas. This indicates that the altered pain experience during placebo analgesia results from active inhibition of nociceptive input. This cognitively triggered endogenous modulation of pain involves, at least in part, the endogenous opioid system. Most recently, functional magnetic resonance imaging data of the human spinal cord revealed that these mechanisms involve the inhibition of nociceptive processing at the level of the dorsal horn of the spinal cord. Here we discuss recent advances in pain imaging research focusing on cognitively triggered endogenous pain control mechanisms and respective implications for future research strategies.
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Brieu N, Beaumont E, Dubeau S, Cohen-Adad J, Lesage F. Characterization of the hemodynamic response in the rat lumbar spinal cord using intrinsic optical imaging and laser speckle. J Neurosci Methods 2010; 191:151-7. [PMID: 20600322 DOI: 10.1016/j.jneumeth.2010.06.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2010] [Revised: 05/28/2010] [Accepted: 06/11/2010] [Indexed: 10/19/2022]
Abstract
Quantifying spinal cord functions is crucial for understanding neurophysiological mechanisms governing the intact and the injured spinal cord. Intrinsic optical imaging (IOI) and laser speckle provides measures of deoxyhemoglobin (HbR) and oxyhemoglobin (HbO(2)) concentrations, blood volume (BV) and blood flow (BF) at high spatial and temporal resolution. In this study we used IOI and laser speckle to characterize the hemodynamic response to neuronal activation in the lumbar spinal cord of anaesthetized rats (N=9). We report consistent temporal variations of HbR, HbO(2), BV and BF located ipsilaterally at L3-L5. Responses were significantly higher when stimulation intensity was increased. Vascular changes extended several millimetres from the epicenter, supporting the venous drainage observed in functional magnetic resonance imaging studies.
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Affiliation(s)
- Nicolas Brieu
- Département de génie électrique, Ecole Polytechnique de Montréal, Montreal, QC, Canada
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45
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Aguilar J, Humanes-Valera D, Alonso-Calviño E, Yague JG, Moxon KA, Oliviero A, Foffani G. Spinal cord injury immediately changes the state of the brain. J Neurosci 2010; 30:7528-37. [PMID: 20519527 PMCID: PMC3842476 DOI: 10.1523/jneurosci.0379-10.2010] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2010] [Revised: 03/16/2010] [Accepted: 04/14/2010] [Indexed: 01/09/2023] Open
Abstract
Spinal cord injury can produce extensive long-term reorganization of the cerebral cortex. Little is known, however, about the sequence of cortical events starting immediately after the lesion. Here we show that a complete thoracic transection of the spinal cord produces immediate functional reorganization in the primary somatosensory cortex of anesthetized rats. Besides the obvious loss of cortical responses to hindpaw stimuli (below the level of the lesion), cortical responses evoked by forepaw stimuli (above the level of the lesion) markedly increase. Importantly, these increased responses correlate with a slower and overall more silent cortical spontaneous activity, representing a switch to a network state of slow-wave activity similar to that observed during slow-wave sleep. The same immediate cortical changes are observed after reversible pharmacological block of spinal cord conduction, but not after sham. We conclude that the deafferentation due to spinal cord injury can immediately (within minutes) change the state of large cortical networks, and that this state change plays a critical role in the early cortical reorganization after spinal cord injury.
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Affiliation(s)
- Juan Aguilar
- Hospital Nacional de Parapléjicos, Servicio de Salud de Castilla–La Mancha, 45071 Toledo, Spain, and
| | - Desiré Humanes-Valera
- Hospital Nacional de Parapléjicos, Servicio de Salud de Castilla–La Mancha, 45071 Toledo, Spain, and
| | - Elena Alonso-Calviño
- Hospital Nacional de Parapléjicos, Servicio de Salud de Castilla–La Mancha, 45071 Toledo, Spain, and
| | - Josué G. Yague
- Hospital Nacional de Parapléjicos, Servicio de Salud de Castilla–La Mancha, 45071 Toledo, Spain, and
| | - Karen A. Moxon
- School of Biomedical Engineering, Science, and Health Systems, Drexel University, Philadelphia, Pennsylvania 19104
| | - Antonio Oliviero
- Hospital Nacional de Parapléjicos, Servicio de Salud de Castilla–La Mancha, 45071 Toledo, Spain, and
| | - Guglielmo Foffani
- Hospital Nacional de Parapléjicos, Servicio de Salud de Castilla–La Mancha, 45071 Toledo, Spain, and
- School of Biomedical Engineering, Science, and Health Systems, Drexel University, Philadelphia, Pennsylvania 19104
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46
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A quantitative comparison of BOLD fMRI responses to noxious and innocuous stimuli in the human spinal cord. Neuroimage 2010; 50:1408-15. [DOI: 10.1016/j.neuroimage.2010.01.043] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2009] [Revised: 12/07/2009] [Accepted: 01/13/2010] [Indexed: 11/22/2022] Open
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47
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Leitch JK, Figley CR, Stroman PW. Applying functional MRI to the spinal cord and brainstem. Magn Reson Imaging 2010; 28:1225-33. [PMID: 20409662 DOI: 10.1016/j.mri.2010.03.032] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2009] [Revised: 03/07/2010] [Accepted: 03/11/2010] [Indexed: 12/28/2022]
Abstract
Functional magnetic resonance imaging of the spinal cord (spinal fMRI) has facilitated the noninvasive visualization of neural activity in the spinal cord (SC) and brainstem of both animals and humans. This technique has yet to gain the widespread usage of brain fMRI, due in part to the intrinsic technical challenges spinal fMRI presents and to the narrower scope of applications it fulfills. Nonetheless, methodological progress has been considerable and rapid. To date, spinal fMRI studies have investigated SC function during sensory or motor task paradigms in spinal cord injury (SCI), multiple sclerosis (MS) and neuropathic pain (NP) patient populations, all of which have yielded consistent and sensitive results. The most recent study in our laboratory has successfully used spinal fMRI to examine cervical SC activity in a SCI patient with a metallic fixation device spanning the C(4) to C(6) vertebrae, a critical step in realizing the clinical utility of the technique. The literature reviewed in this article suggests that spinal fMRI is poised for usage in a wide range of patient populations, as multiple groups have observed intriguing, yet consistent, results using standard, readily available MR systems and hardware. The next step is the implementation of this technique in the clinic to supplement standard qualitative behavioral assessments of SCI. Spinal fMRI may offer insight into the subtleties of function in the injured and diseased SC, and support the development of new methods for treatment and monitoring.
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Affiliation(s)
- Jordan K Leitch
- Centre for Neuroscience Studies, Queen's University, Kingston, Ontario, Canada
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48
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BOLD signal responses to controlled hypercapnia in human spinal cord. Neuroimage 2010; 50:1074-84. [DOI: 10.1016/j.neuroimage.2009.12.122] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2009] [Revised: 12/08/2009] [Accepted: 12/31/2009] [Indexed: 01/21/2023] Open
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49
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Shanthanna H. Is preoperative opioid utilization an important factor in predicting phantom limb pain? Can J Anaesth 2010; 57:620-1. [PMID: 20300908 DOI: 10.1007/s12630-010-9296-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2010] [Accepted: 03/01/2010] [Indexed: 11/30/2022] Open
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50
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Verbal fluency deficits and altered lateralization of language brain areas in individuals genetically predisposed to schizophrenia. Schizophr Res 2009; 115:202-8. [PMID: 19840895 PMCID: PMC4841274 DOI: 10.1016/j.schres.2009.09.033] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2009] [Revised: 09/18/2009] [Accepted: 09/22/2009] [Indexed: 11/21/2022]
Abstract
Alterations of verbal fluency may correlate with deficits of gray matter volume and hemispheric lateralization of language brain regions like the pars triangularis (PT) in schizophrenia. Examining non-psychotic individuals at high genetic risk (HR) for schizophrenia may clarify if these deficits represent heritable trait markers or state dependent phenomena. We assessed adolescent and young adult HR subjects (N=60) and healthy controls (HC; N=42) using verbal fluency tests and Freesurfer to process T1-MRI scans. We hypothesized volumetric and lateralization alterations of the PT and their correlation with verbal fluency deficits. HR subjects had letter verbal fluency deficits (controlling for IQ), left PT deficits (p=.00), (controlling ICV) and reversal of the L>R PT asymmetry noted in HC. Right Heschl's (p=.00), left supramarginal (p=.00) and right angular gyrii (p=.02) were also reduced in HR subjects. The L>R asymmetry of the Heschl's gyrus seen in HC was exaggerated and asymmetries of L>R of supramarginal and R>L of angular gyri, seen in HC were attenuated in HR subjects. L>R asymmetry of the PT predicted better verbal fluency across the pooled HR and HC groups. Young relatives of schizophrenia patients have verbal fluency deficits, gray matter volume deficits and reversed asymmetry of the pars triangularis. A reversed structural asymmetry of the PT in HR subjects may impair expressive language abilities leading to verbal fluency deficits. Volumetric deficits and altered asymmetry in inferior parietal and Heschl's gyrii may accompany genetic liability to schizophrenia.
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