Optogenetic dissection of a behavioural module in the vertebrate spinal cord. Nature

Helen Wills Neuroscience Institute and Department of Molecular and Cell Biology, University of California in Berkeley, Berkeley, California 94720, USA.
Nature (Impact Factor: 41.46). 09/2009; 461(7262):407-10. DOI: 10.1038/nature08323
Source: PubMed


Locomotion relies on neural networks called central pattern generators (CPGs) that generate periodic motor commands for rhythmic movements. In vertebrates, the excitatory synaptic drive for inducing the spinal CPG can originate from either supraspinal glutamatergic inputs or from within the spinal cord. Here we identify a spinal input to the CPG that drives spontaneous locomotion using a combination of intersectional gene expression and optogenetics in zebrafish larvae. The photo-stimulation of one specific cell type was sufficient to induce a symmetrical tail beating sequence that mimics spontaneous slow forward swimming. This neuron is the Kolmer-Agduhr cell, which extends cilia into the central cerebrospinal-fluid-containing canal of the spinal cord and has an ipsilateral ascending axon that terminates in a series of consecutive segments. Genetically silencing Kolmer-Agduhr cells reduced the frequency of spontaneous free swimming, indicating that activity of Kolmer-Agduhr cells provides necessary tone for spontaneous forward swimming. Kolmer-Agduhr cells have been known for over 75 years, but their function has been mysterious. Our results reveal that during early development in zebrafish these cells provide a positive drive to the spinal CPG for spontaneous locomotion.

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    • "Furthermore, this phenotype was specific to the tissue expression of LiGluR as expression throughout the entire nervous system led to complete paralysis, but expression in the heart led to no phenotypic changes. Later, this group limited LiGluR expression to a single spinal neuron type, Kolmer-Agduhr cells, to identify their role in spontaneous locomotion during zebrafish development, a function previously unknown (Wyart et al. 2009). These studies demonstrated that it is possible to use light to manipulate LiGLuR in vivo making it possible to dissect the role of neural circuits in behavior. "
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    • "We tested immunoreactivity pattern for both rabbit and rat anti-glycine antibodies, and we obtained similar patterns of staining. The polyclonal rabbit anti-GABA antibody (Sigma, code A2052) has previously been used in many studies with zebrafish (Higashijima et al., 2004; Mueller et al., 2006; Wyart et al., 2009) and specific subpopulations of neurons were labeled with this antibody. In Higashijima et al. (2004), double staining with immunohistochemistry with rabbit anti- GABA antibody (Sigma) and in situ hybridization with GAD probes (GAD65 and GAD67) performed and almost complete overlap of both staining was observed. "
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