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Spinal Efference Copy Signaling and Gaze Stabilization during Locomotion in Juvenile Xenopus Frogs
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EN
Article de revue
Este ítem está publicado en
Journal of Neuroscience. 2013-03-06, vol. 33, n° 10, p. 4253-4264
Resumen en inglés
In swimming Xenopus laevis tadpoles, gaze stabilization is achieved by efference copies of spinal locomotory CPG output that produce rhythmic extraocular motor activity appropriate for minimizing motion-derived visual ...Leer más >
In swimming Xenopus laevis tadpoles, gaze stabilization is achieved by efference copies of spinal locomotory CPG output that produce rhythmic extraocular motor activity appropriate for minimizing motion-derived visual disturbances. During metamorphosis, Xenopus switches its locomotory mechanism from larval tail-based undulatory movements to bilaterally synchronous hindlimb kick propulsion in the adult. The change in locomotory mode leads to body motion dynamics that no longer require conjugate left-right eye rotations for effective retinal image stabilization. Using in vivo kinematic analyses, in vitro electrophysiological recordings and specific CNS lesions, we have investigated spino-extraocular motor coupling in the juvenile frog and the underlying neural pathways to understand how gaze control processes are altered in accordance with the animal's change in body plan and locomotor strategy. Recordings of extraocular and limb motor nerves during spontaneous "fictive" swimming in isolated CNS preparations revealed that there is indeed a corresponding change in spinal efference copy control of extraocular motor output. In contrast to fictive larval swimming where alternating bursts occur in bilateral antagonistic horizontal extraocular nerves, during adult fictive limb-kicking, these motor nerves are synchronously active in accordance with the production of convergent eye movements during the linear head accelerations resulting from forward propulsion. Correspondingly, the neural pathways mediating spino-extraocular coupling have switched from contralateral to strictly ipsilateral ascending influences that ensure a coactivation of bilateral extraocular motoneurons with synchronous left-right limb extensions. Thus, adaptive developmental plasticity during metamorphosis enables spinal CPG-driven extraocular motor activity to match the changing requirements for eye movement control during self-motion.< Leer menos
Palabras clave en inglés
Action Potentials
Animals
Anura
Biomechanical Phenomena
Brain Stem
Extremities
Female
Fixation
Ocular
Functional Laterality
In Vitro Techniques
Male
Metamorphosis
Biological
Nerve Net
Neural Pathways
Optic Nerve Injuries
Spinal Cord
Spinal Cord Injuries
Statistics, Nonparametric
Swimming
Video Recording
Xenopus laevis
Centros de investigación