During development, all animals undergo major adaptations to accommodate behavioral flexibility and diversity. How these adaptations are reflected in the changes in the motor circuits controlling our behaviors remains poorly understood. Here, we show, using a combination of techniques applied at larval and adult zebrafish stages, that the pattern-generating V0d inhibitory interneurons within the locomotor circuit undergo a developmental switch in their role. In larvae, we show that V0d interneurons have a primary function in high-speed motor behavior yet are redundant for explorative swimming. By contrast, adult V0d interneurons have diversified into speed-dependent subclasses, with an overrepresentation of those active at the slowest speeds. The ablation of V0d interneurons in adults disrupts slow explorative swimming, which is associated with a loss of mid-cycle inhibition onto target motoneurons. Thus, we reveal a developmental switch in V0d interneuron function from a role in high-speed motor behavior to a function in timing and thus coordinating slow explorative locomotion. Our study suggests that early motor circuit composition is not predictive of the adult system but instead undergoes major functional transformations during development.
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http://dx.doi.org/10.1016/j.cub.2022.06.059 | DOI Listing |
Curr Biol
August 2022
Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden. Electronic address:
During development, all animals undergo major adaptations to accommodate behavioral flexibility and diversity. How these adaptations are reflected in the changes in the motor circuits controlling our behaviors remains poorly understood. Here, we show, using a combination of techniques applied at larval and adult zebrafish stages, that the pattern-generating V0d inhibitory interneurons within the locomotor circuit undergo a developmental switch in their role.
View Article and Find Full Text PDFJ Neurosci
April 2021
Department of Neuroscience, Karolinska Institute, SE-17177 Stockholm, Sweden
Locomotion, scratching, and stabilization of the body orientation in space are basic motor functions which are critically important for animal survival. Their execution requires coordinated activity of muscles located in the left and right halves of the body. Commissural interneurons (CINs) are critical elements of the neuronal networks underlying the left-right motor coordination.
View Article and Find Full Text PDFFront Cell Neurosci
November 2019
Department of Medical Neuroscience, Brain Repair Centre, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada.
Commissural interneurons (CINs) mediate interactions between rhythm-generating locomotor circuits located on each side of the spinal cord and are necessary for left-right limb coordination during locomotion. While glutamatergic V3 CINs have been implicated in left-right coordination, their functional connectivity remains elusive. Here, we addressed this issue by combining experimental and modeling approaches.
View Article and Find Full Text PDFNat Commun
September 2019
Department of Neurobiology, Northwestern University, Evanston, IL, 60208, USA.
In all vertebrates, excitatory spinal interneurons execute dynamic adjustments in the timing and amplitude of locomotor movements. Currently, it is unclear whether interneurons responsible for timing control are distinct from those involved in amplitude control. Here, we show that in larval zebrafish, molecularly, morphologically and electrophysiologically distinct types of V2a neurons exhibit complementary patterns of connectivity.
View Article and Find Full Text PDFDev Biol
December 2017
Institut Jacques Monod, CNRS UMR7592, Université Paris Diderot, Sorbonne Paris Cité, 75205 Paris Cedex, France. Electronic address:
Transcription factors are key orchestrators of the emergence of neuronal diversity within the developing spinal cord. As such, the two paralogous proteins Pax3 and Pax7 regulate the specification of progenitor cells within the intermediate neural tube, by defining a neat segregation between those fated to form motor circuits and those involved in the integration of sensory inputs. To attain insights into the molecular means by which they control this process, we have performed detailed phenotypic analyses of the intermediate spinal interneurons (IN), namely the dI6, V0, V0 and V1 populations in compound null mutants for Pax3 and Pax7.
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