Functional organization of locomotor interneurons in the ventral lumbar spinal cord of the newborn rat.
PLoS ONE. 2011-06-17; 6(6): e20529
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1. PLoS One. 2011;6(6):e20529. doi: 10.1371/journal.pone.0020529. Epub 2011 Jun 17.
Functional organization of locomotor interneurons in the ventral lumbar spinal
cord of the newborn rat.
Antri M(1), Mellen N, Cazalets JR.
(1)Université de Bordeaux, Centre National de la Recherche Scientifique, Institut
des Neurosciences Cognitives et Intégratives d’Aquitaine, Unité Mixte de
Recherche 5287, Bordeaux, France.
Although the mammalian locomotor CPG has been localized to the lumbar spinal
cord, the functional-anatomical organization of flexor and extensor interneurons
has not been characterized. Here, we tested the hypothesis that flexor and
extensor interneuronal networks for walking are physically segregated in the
lumbar spinal cord. For this purpose, we performed optical recordings and lesion
experiments from a horizontally sectioned lumbar spinal cord isolated from
neonate rats. This ventral hemi spinal cord preparation produces well-organized
fictive locomotion when superfused with 5-HT/NMDA. The dorsal surface of the
preparation was visualized using the Ca(2+) indicator fluo-4 AM, while
simultaneously monitoring motor output at ventral roots L2 and L5. Using calcium
imaging, we provided a general mapping view of the interneurons that maintained a
stable phase relationship with motor output. We showed that the dorsal surface of
L1 segment contains a higher density of locomotor rhythmic cells than the other
segments. Moreover, L1 segment lesioning induced the most important changes in
the locomotor activity in comparison with lesions at the T13 or L2 segments.
However, no lesions led to selective disruption of either flexor or extensor
output. In addition, this study found no evidence of functional parcellation of
locomotor interneurons into flexor and extensor pools at the dorsal-ventral
midline of the lumbar spinal cord of the rat.
PMID: 21698092 [Indexed for MEDLINE]