Adaptive plasticity of spino-extraocular motor coupling during locomotion in metamorphosing Xenopus laevis.
Langue
EN
Article de revue
Ce document a été publié dans
Journal of Experimental Biology. 2016-04-15, vol. 219, n° Pt 8, p. 1110-1121
Résumé en anglais
During swimming in the amphibian ITALIC! Xenopus laevis, efference copies of rhythmic locomotor commands produced by the spinal central pattern generator (CPG) can drive extraocular motor output appropriate for producing ...Lire la suite >
During swimming in the amphibian ITALIC! Xenopus laevis, efference copies of rhythmic locomotor commands produced by the spinal central pattern generator (CPG) can drive extraocular motor output appropriate for producing image-stabilizing eye movements to offset the disruptive effects of self-motion. During metamorphosis, ITALIC! X. laevisremodels its locomotor strategy from larval tail-based undulatory movements to bilaterally synchronous hindlimb kicking in the adult. This change in propulsive mode results in head/body motion with entirely different dynamics, necessitating a concomitant switch in compensatory ocular movements from conjugate left-right rotations to non-conjugate convergence during the linear forward acceleration produced during each kick cycle. Here, using semi-intact or isolated brainstem/spinal cord preparations at intermediate metamorphic stages, we monitored bilateral eye motion along with extraocular, spinal axial and limb motor nerve activity during episodes of spontaneous fictive swimming. Our results show a progressive transition in spinal efference copy control of extraocular motor output that remains adapted to offsetting visual disturbances during the combinatorial expression of bimodal propulsion when functional larval and adult locomotor systems co-exist within the same animal. In stages at metamorphic climax, spino-extraocular motor coupling, which previously derived from axial locomotor circuitry alone, can originate from both axial and ITALIC! de novohindlimb CPGs, although the latter's influence becomes progressively more dominant and eventually exclusive as metamorphosis terminates with tail resorption. Thus, adaptive interactions between locomotor and extraocular motor circuitry allows CPG-driven efference copy signaling to continuously match the changing spatio-temporal requirements for visual image stabilization throughout the transitional period when one propulsive mechanism emerges and replaces another.< Réduire
Mots clés en anglais
Adaptation
Physiological
Animals
Eye Movements
Locomotion
Metamorphosis
Biological
Models
Biological
Motor Activity
Spinal Cord
Swimming
Xenopus laevis
Project ANR
VAriabilité du tranfert vertical et tropHIque de l'azote (N2) fixé dans le sud-ouEst Pacifique et impact potentiel sur la pompe biologique à carbone - ANR-13-JS06-0002