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Journal ArticleDOI

Cortical Reorganization of Sensorimotor Systems and the Role of Intracortical Circuits After Spinal Cord Injury

07 Jun 2018-Neurotherapeutics (Springer International Publishing)-Vol. 15, Iss: 3, pp 588-603
TL;DR: This review focuses on the reorganization of cortical networks observed after injury and posits a role of intracortical circuits in recovery.
About: This article is published in Neurotherapeutics.The article was published on 2018-06-07 and is currently open access. It has received 31 citations till now. The article focuses on the topics: Spinal cord injury & Motor learning.
Citations
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Journal ArticleDOI
14 May 2020-Cell
TL;DR: It is demonstrated that subperceptual neural signals can be decoded from the cortex and transformed into conscious perception, significantly augmenting function.

75 citations

Journal ArticleDOI
TL;DR: The mechanisms through which the neuroimmune system mediates plasticity after CNS injury are reviewed to offer valuable therapeutic insight into how to promote adaptive plasticity and/or diminish maladaptive plasticity, respectively.
Abstract: Following an injury to the central nervous system (CNS), spontaneous plasticity is observed throughout the neuraxis and affects multiple key circuits. Much of this spontaneous plasticity can elicit beneficial and deleterious functional outcomes, depending on the context of plasticity and circuit affected. Injury-induced activation of the neuroimmune system has been proposed to be a major factor in driving this plasticity, as neuroimmune and inflammatory factors have been shown to influence cellular, synaptic, structural, and anatomical plasticity. Here, we will review the mechanisms through which the neuroimmune system mediates plasticity after CNS injury. Understanding the role of specific neuroimmune factors in driving adaptive and maladaptive plasticity may offer valuable therapeutic insight into how to promote adaptive plasticity and/or diminish maladaptive plasticity, respectively.

24 citations


Cites background from "Cortical Reorganization of Sensorim..."

  • ...…as well as a shift in electrical and neurochemical activity (e.g., spontaneous ectopic discharge, enhanced excitability; reviewed in more detail in Molander et al., 1994; Bester et al., 2000; Navarro et al., 2007; Devor, 2009; Hou et al., 2009; Latremoliere and Woolf, 2009; NitzanLuques et al.,…...

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Journal ArticleDOI
TL;DR: A meta-analysis of the correlation between EDSS scores and CSCA at 3T MRI in MS demonstrated that CSC a was negatively and moderately correlated with E DSS scores, and encouraged more studies using reliable and consistent methods to explore whether CSCa is suitable as a predictor for MS progression.
Abstract: Background Cervical spinal cord atrophy (CSCA), which partly reflects the axonal loss in the spinal cord, is increasingly recognized as a valuable predictor of disease outcome. However, inconsistent results have been reported regarding the correlation of CSCA and clinical disability in multiple sclerosis (MS). The aim of this meta-analysis was to synthesize the available data obtained from 3.0-Tesla (3T) MRI scanners and to explore the relationship between CSCA and scores on the Expanded Disability Status Scale (EDSS). Methods We searched PubMed, Embase, and Web of Science for articles published from the database inception to February 1, 2019. The quality of the articles was assessed according to a quality evaluation checklist which was created based on the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines. We conducted a meta-analysis of the correlation between EDSS scores and CSCA at 3T MRI in MS. Results Twenty-two eligible studies involving 1933 participants were incorporated into our meta-analysis. Our results demonstrated that CSCA was negatively and moderately correlated with EDSS scores (rs = -0.42, 95% CI: -0.51 to -0.32; p Conclusions The correlation between CSCA and EDSS scores was significant but moderate. We encourage more studies using reliable and consistent methods to explore whether CSCA is suitable as a predictor for MS progression.

23 citations

Journal ArticleDOI
01 Mar 2021-eLife
TL;DR: These results are the first neuron level evidence of touch encoding in human PPC and its cognitive engagement during tactile imagery which may reflect semantic processing, sensory anticipation, and imagined touch.
Abstract: In the human posterior parietal cortex (PPC), single units encode high-dimensional information with partially mixed representations that enable small populations of neurons to encode many variables relevant to movement planning, execution, cognition, and perception. Here, we test whether a PPC neuronal population previously demonstrated to encode visual and motor information is similarly engaged in the somatosensory domain. We recorded neurons within the PPC of a human clinical trial participant during actual touch presentation and during a tactile imagery task. Neurons encoded actual touch at short latency with bilateral receptive fields, organized by body part, and covered all tested regions. The tactile imagery task evoked body part-specific responses that shared a neural substrate with actual touch. Our results are the first neuron-level evidence of touch encoding in human PPC and its cognitive engagement during a tactile imagery task, which may reflect semantic processing, attention, sensory anticipation, or imagined touch.

18 citations


Cites background from "Cortical Reorganization of Sensorim..."

  • ...With mid-cervical lesions, for instance, there is an initial loss of BA 3b hand representations, and a 541 slight expansion in face representation at approximately two years (75, 76)....

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  • ...Although significant axonal 542 sprouting has been demonstrated to occur at the site of deafferentation in the spinal cord, with increased 543 projections to brainstem nuclei, the changes observed in the somatosensory cortex are significantly 544 smaller (75, 76)....

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  • ...Moreover, the reorganization in higher order somatosensory centers such as the 545 secondary somatosensory cortex is even more restricted than in BA 3b (76)....

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Journal ArticleDOI
TL;DR: Paired associative stimulation with 100 Hz PNS is effective and feasible for clinical applications and induces robust motor-evoked potential (MEP) potentiation in healthy subjects.
Abstract: Paired associative stimulation (PAS), a combination of transcranial magnetic stimulation (TMS) with peripheral nerve stimulation (PNS), is emerging as a promising tool for alleviation of motor deficits in neurological disorders. The effectiveness and feasibility of PAS protocols are essential for their use in clinical practice. Plasticity induction by conventional PAS can be variable and unstable. Protocols effective in challenging clinical conditions are needed. We have shown previously that PAS employing 50 Hz PNS enhances motor performance in chronic spinal cord injury patients and induces robust motor-evoked potential (MEP) potentiation in healthy subjects. Here we investigated whether the effectiveness of PAS can be further enhanced. Potentiation of MEPs up to 60 minutes after PAS with PNS frequencies of 25, 50, and 100 Hz was tested in healthy subjects. PAS with 100 Hz PNS was more effective than 50 (P = 0.009) and 25 Hz (P = 0.016) protocols. Moreover, when administered for 3 days, PAS with 100 Hz led to significant MEP potentiation on the 3rd day (P = 0.043) even when the TMS target was selected suboptimally (modelling cases where finding an optimal site for TMS is problematic due to a neurological disease). PAS with 100 Hz PNS is thus effective and feasible for clinical applications.

17 citations

References
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Journal ArticleDOI
21 Jun 1996-Science
TL;DR: The results suggest that, after local damage to the motor cortex, rehabilitative training can shape subsequent reorganization in the adjacent intact cortex, and that the undamaged motor cortex may play an important role in motor recovery.
Abstract: Substantial functional reorganization takes place in the motor cortex of adult primates after a focal ischemic infarct, as might occur in stroke. A subtotal lesion confined to a small portion of the representation of one hand was previously shown to result in a further loss of hand territory in the adjacent, undamaged cortex of adult squirrel monkeys. In the present study, retraining of skilled hand use after similar infarcts resulted in prevention of the loss of hand territory adjacent to the infarct. In some instances, the hand representations expanded into regions formerly occupied by representations of the elbow and shoulder. Functional reorganization in the undamaged motor cortex was accompanied by behavioral recovery of skilled hand function. These results suggest that, after local damage to the motor cortex, rehabilitative training can shape subsequent reorganization in the adjacent intact cortex, and that the undamaged motor cortex may play an important role in motor recovery.

1,821 citations

Journal ArticleDOI
08 Jun 1995-Nature
TL;DR: A very strong direct relationship is reported between the amount of cortical reorganization and the magnitude of phantom limb pain (but not non-painful phantom phenomena) experienced after arm amputation, indicating that phantom-limb pain is related to, and may be a consequence of, plastic changes in primary somatosensory cortex.
Abstract: Although phantom-limb pain is a frequent consequence of the amputation of an extremity, little is known about its origin. On the basis of the demonstration of substantial plasticity of the somatosensory cortex after amputation or somatosensory deafferentation in adult monkeys, it has been suggested that cortical reorganization could account for some non-painful phantom-limb phenomena in amputees and that cortical reorganization has an adaptive (that is, pain-preventing) function. Theoretical and empirical work on chronic back pain has revealed a positive relationship between the amount of cortical alteration and the magnitude of pain, so we predicted that cortical reorganization and phantom-limb pain should be positively related. Using non-invasive neuromagnetic imaging techniques to determine cortical reorganization in humans, we report a very strong direct relationship (r = 0.93) between the amount of cortical reorganization and the magnitude of phantom limb pain (but not non-painful phantom phenomena) experienced after arm amputation. These data indicate that phantom-limb pain is related to, and may be a consequence of, plastic changes in primary somatosensory cortex.

1,692 citations

01 Jan 1950

1,483 citations

Journal ArticleDOI
TL;DR: The finding that cocontracting muscles in the behavior come to be represented together in the cortex argues that, as in sensory cortices, temporal correlations drive emergent changes in distributed motor cortex representations.
Abstract: This study was undertaken to document plastic changes in the functional topography of primary motor cortex (M1) that are generated in motor skill learning in the normal, intact primate. Intracortical microstimulation mapping techniques were used to derive detailed maps of the representation of movements in the distal forelimb zone of M1 of squirrel monkeys, before and after behavioral training on two different tasks that differentially encouraged specific sets of forelimb movements. After training on a small-object retrieval task, which required skilled use of the digits, their evoked-movement digit representations expanded, whereas their evoked-movement wrist/forearm representational zones contracted. These changes were progressive and reversible. In a second motor skill exercise, a monkey pronated and supinated the forearm in a key (eyebolt)-turning task. In this case, the representation of the forearm expanded, whereas the digit representational zones contracted. These results show that M1 is alterable by use throughout the life of an animal. These studies also revealed that after digit training there was an areal expansion of dual-response representations, that is, cortical sectors over which stimulation produced movements about two or more joints. Movement combinations that were used more frequently after training were selectively magnified in their cortical representations. This close correspondence between changes in behavioral performance and electrophysiologically defined motor representations indicates that a neurophysiological correlate of a motor skill resides in M1 for at least several days after acquisition. The finding that cocontracting muscles in the behavior come to be represented together in the cortex argues that, as in sensory cortices, temporal correlations drive emergent changes in distributed motor cortex representations.

1,401 citations

Journal ArticleDOI
17 Dec 2009-Nature
TL;DR: It is shown that learning and daily sensory experience leave minute but permanent marks on cortical connections and suggest that lifelong memories are stored in largely stably connected synaptic networks.
Abstract: Connections between neurons are thought to be remodelled when we learn new tasks or acquire new information. However, this plasticity must also occur against a backdrop of stable memory maintenance. In mice, a paradigm of either enhanced sensory experience or specific motor learning produced new putative neuronal connections that remained stable alongside developmentally preserved connections much later in life. This suggests that learning can produce changes in the neuronal connectivity that can be stable for the lifetime of the network. Connections between neurons are thought to be remodelled when we learn new tasks or acquire new information; however, it is unclear how neural circuits undergo continuous synaptic changes during learning while maintaining lifelong memories. Here, by following post-synaptic dendritic spines in the mouse cortex, it is shown that a small fraction of new spines induced by novel experience are preserved and provide a structural basis for lifelong memory retention. Changes in synaptic connections are considered essential for learning and memory formation1,2,3,4,5,6. However, it is unknown how neural circuits undergo continuous synaptic changes during learning while maintaining lifelong memories. Here we show, by following postsynaptic dendritic spines over time in the mouse cortex7,8, that learning and novel sensory experience lead to spine formation and elimination by a protracted process. The extent of spine remodelling correlates with behavioural improvement after learning, suggesting a crucial role of synaptic structural plasticity in memory formation. Importantly, a small fraction of new spines induced by novel experience, together with most spines formed early during development and surviving experience-dependent elimination, are preserved and provide a structural basis for memory retention throughout the entire life of an animal. These studies indicate that learning and daily sensory experience leave minute but permanent marks on cortical connections and suggest that lifelong memories are stored in largely stably connected synaptic networks.

1,057 citations