Project description:Neural circuits in the spinal cord have a critical role in integrating sensory information and descending commands to coordinate body movements. Defining the functional diversity of spinal neurons is therefore essential for understanding the mechanisms underlying motor control. In this study, by combining anatomical, molecular, and functional analyses in mice, we identified and characterized a subtype of ascending spinal neurons belonging to the V0g family. We found that V0g ascending neurons are integrated in lumbar sensorimotor circuits and their function is specifically required for the execution of precise limb movements necessary for skilled locomotion. This work advances our understanding of the functional organization of V0 neurons and highlights a previously unappreciated role in adjusting body movements to the more demanding needs of skilled locomotor tasks
Project description:The flexibility of motor actions is ingrained in the diversity of neurons and how they are organized into functional circuit modules, yet our knowledge of the molecular underpinning of motor circuit modularity remains limited. Locomotion is a motor behavior characterized by sudden changes in speed and strength enabled by the coordinated recruitment of different motoneuron subtypes. Here we use adult zebrafish to link the molecular diversity of motoneurons and the rhythm-generating V2a interneurons with their modular circuit organization that is responsible for changes in locomotor speed. We show that the molecular diversity of motoneurons and V2a interneurons reflects their functional segregation into slow, intermediate or fast subtypes. Furthermore, we reveal shared molecular signatures between V2a interneurons and motoneurons of the three speed circuit modules. Overall, by characterizing how the molecular diversity of motoneurons and V2a interneurons relates to their function, connectivity and behavior, our study provides important insights not only into the molecular mechanisms for neuronal and circuit diversity for locomotor flexibility but also for charting circuits for motor actions in general.
Project description:Electrical stimulation can augment or modify neuronal function and can have therapeutic benefits for certain neurological disorders. There is evidence that enhancing spinal excitability with either epidural or transcutaneous stimulation can restore some volitional motor output after spinal cord injury (SCI). Lumbosacral epidural stimulation temporarily improves locomotor and autonomic function in both rodents and humans with SCI. When combined with overground locomotor training enabled by a weight-supporting device, epidural electrical stimulation (EES) promotes extensive reorganization of residual neural pathways that improves locomotion after stopping stimulation. However, the exact mechanism underlying the reconstruction of spinal cord neural circuits with electrical stimulation is not yet known. Thus, we developed a epidural electrical and muscle stimulation(EEMS) system at the interface of the spinal cord and muscle to mimic feedforward and feedback electrical signals in spinal sensorimotor circuits. Using methods of motor function evaluation, neural circuit tracing and neural signal recording, we discovered a unique stimulus frequency of 10-20 Hz under EEMS conditions that was required for structural and functional reconstruction of spinal sensorimotor circuits. Single-cell transcriptome analysis of EEMS activated motoneurons characterized molecular networks involved in spinal sensorimotor circuit reconstruction. This study provides insights into neural signal decoding during spinal sensorimotor circuit reconstruction, and indicates a technological approach for the clinical treatment of SCI.
Project description:This SuperSeries is composed of the following subset Series: GSE36241: Identification of a FOXO3/IRF7 circuit that limits inflammatory sequelae of antiviral responses (ChIP-Seq) GSE37051: Identification of a FOXO3/IRF7 circuit that limits inflammatory sequelae of antiviral responses (expression) Refer to individual Series
Project description:Hv1 upregulation worsens spinal, spleen, and lung molecular pathology and impairs locomotion after spinal cord injury in aged male mice
Project description:Astrocytes, the most abundant cells in the central nervous system, promote synapse formation and help refine neural connectivity. Although they are allocated to spatially distinct regional domains during development, it is unknown whether region-restricted astrocytes are functionally heterogeneous. Here we show that postnatal spinal cord astrocytes express several region-specific genes, and that ventral astrocyte-encoded Semaphorin3a (Sema3a) is required for proper motor neuron and sensory neuron circuit organization. Loss of astrocyte-encoded Sema3a led to dysregulated α−motor neuron axon initial segment orientation, markedly abnormal synaptic inputs, and selective death of α−but not of adjacent γ−motor neurons. Additionally, a subset of TrkA+ sensory afferents projected to ectopic ventral positions. These findings demonstrate that stable maintenance of a positional cue by developing astrocytes influences multiple aspects of sensorimotor circuit formation. More generally, they suggest that regional astrocyte heterogeneity may help to coordinate postnatal neural circuit refinement. 12 total samples consisting of three biological replicates each of flow sorted postnatal day 7 dorsal spinal cord astrocytes, ventral spinal cord astrocytes, dorsal SC non astrocytes, and ventral SC non astrocytes
Project description:Human iPSC-derived thoracic spinal cord organoids were transplanted into spinal cord injury mice, and spinal cord tissue was collected after 7 weeks. The transplantation resulted in functional recovery and neural circuit remodeling in the injured mice.
Project description:Neural circuits in the spinal cord transform instructive signals from the brain into well-coordinated locomotor movements by virtue of rhythm-generating components. Although evidence suggests that excitatory interneurons are the essence of locomotor rhythm generation, their molecular identity and the assessment of their necessity have remained unclear. Here we show, using larval zebrafish, that V2a interneurons represent an intrinsic source of excitation necessary for the normal expression of the locomotor rhythm. Acute and selective ablation of these interneurons increases the threshold of induction of swimming activity, decreases the burst frequency, and alters the coordination of the rostro-caudal propagation of activity. Thus, our results argue that V2a interneurons represent a source of excitation that endows the spinal circuit with the capacity to generate locomotion.
Project description:Spinal cord injury (SCI) induces both intraspinal damage and systemic organ pathology, with aging as a major determinant of outcome. However, how advanced age exacerbates SCI pathology remains unclear. The voltage-gated proton channel Hv1, a regulator of immune activation, increases with age and after SCI, and its deletion is neuroprotective in young mice. Thus, we hypothesized that age-related Hv1 upregulation worsens spinal cord, spleen, and lung pathology and hinders locomotor recovery after SCI through immune modulation. Using aged Hv1 KO and WT male mice subjected to moderate SCI, we assessed behavioral and molecular outcomes. Transcriptomic analysis revealed that Hv1 mRNA expression was higher in the brains of aged sham mice and further upregulated in injured spinal cord tissues. Spinal cord RNA-seq showed acute innate immune and cytokine activation in both genotypes. Hv1 deletion enhanced chromatin remodeling, epigenetic and Wnt signaling, while suppressing NF-κB–driven inflammation and oxidative stress–induced apoptosis. In the spleen, Hv1 depletion enhanced immune responses while suppressing mitosis. T cell and leukocyte activation increased, whereas lung cytokine signaling decreased. At 6 weeks after SCI, Hv1 KO mice showed elevated expression of genes related to circadian rhythm and T cell proliferation in the spinal cord, increased mitotic gene expression but reduced adaptive immunity in the spleen, and enhanced immune activation with decreased cilium activity in the lungs.