Multiple spontaneous rhythmic activity patterns generated by the embryonic mouse spinal cord occur within a specific developmental time window
Journal of Neurophysiology. 2004-05-01; 91(5): 2101-2109
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1. J Neurophysiol. 2004 May;91(5):2101-9. Epub 2004 Jan 14.
Multiple spontaneous rhythmic activity patterns generated by the embryonic mouse
spinal cord occur within a specific developmental time window.
Yvert B(1), Branchereau P, Meyrand P.
(1)Laboratoire de Neurobiologie des Réseaux, Unité Mixte de Recherche 5816,
Centre National de la Recherche Scientifique and Université Bordeaux 1, 33405
Talence Cedex, France.
Spontaneous rhythmic activity is a ubiquitous phenomenon in developing neural
networks and is assumed to play an important role in the elaboration of mature
circuitry. Here we describe the day-by-day evolution of spontaneous activity in
the embryonic mouse spinal cord and show that, at a specific developmental stage,
2 distinct rhythms coexist. On embryonic days E12.5 and E13.5, we observed a
single type of regularly recurring short spike-episodes synchronized across
cervical, thoracic, and lumbar levels. By E14.5, in addition to this motor
rhythm, another type of spontaneous synchronous activity appeared, characterized
by much longer lasting episodes separated by longer time intervals. On E15.5,
these long episodes disappeared. Short episodes were less numerous and more
irregular except at the cervical level where a rhythm was occasionally observed.
By E16.5, this cervical rhythm became more robust, whereas the lumbar level fell
almost silent. Surprisingly, at E17.5, spontaneous activity resumed at caudal
levels, now characterized by numerous erratic short episodes. A striking
ontogenetic feature of spontaneous activity was the occurrence of long episodes
only at E14.5. Although concomitant at all levels of the spinal cord, long
episodes displayed different patterns along the spinal cord, with tonic firing at
the thoracic level and rhythmic discharge with occasional sequences of left/right
alternation at the lumbar level. Thus at E14.5, the originally synchronized
network has started to segregate into more specialized subnetworks. In
conclusion, this work suggests that ongoing spontaneous rhythms do not follow a
smooth evolution during maturation, but rather undergo profound changes at very
PMID: 14724265 [Indexed for MEDLINE]