Coordinated motor output in the hindlimb of the 7 day chick embryo

A. Bekoff, P. S.G. Stein, V. Hamburger

Research output: Contribution to journalArticlepeer-review

75 Scopus citations

Abstract

Electromyographic recordings from individual identified ankle muscles of the 7 day chick embryo (stage 31) were used to determine the organization of motor output at a developmental stage shortly after the onset of spontaneous motility in the leg. During spontaneous motility of the embryo, the electromyographic recordings from the gastrocnemius, peroneus, and tibialis muscles displayed bursts of motor unit activity which alternated with periods of little or no activity. Since the control of skeletal muscle in the chick embryo is neurogenic rather than myogenic, these findings imply that the motoneurons to a given muscle are driven by a common source. Since flexor and extensor muscles are activated at different times, different central connections to flexor and extensor motoneurons must be present in the central nervous system of the 7 day embryo. Moreover, since inhibition is known to play an important role in the selective activation of agonist and antagonist muscles, the results suggest that functional inhibitory synapses may be present in the lumbosacral central nervous system at this stage of development. The basic pattern of muscle activation observed in the 7 day embryo is similar to that seen in older embryos. Since these patterns appear prior to the time at which motor responses to sensory stimulation of the leg can be demonstrated, it is likely that the neural pattern generating circuits for selective activation of muscles are established in the central nervous system without reliance on functional reflexes.

Original languageEnglish
Pages (from-to)1245-1248
Number of pages4
JournalProceedings of the National Academy of Sciences of the United States of America
Volume72
Issue number4
DOIs
StatePublished - 1975

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