Rhythmic Activity Patterns of Motoneurones and Interneurones in the Embryonic Chick Spinal Cord
We have studied the organization of patterned motor activity in the developing spinal cord of the chick embryo using optical and electrophysiological methods. Optical imaging of motoneurones filled with calcium dyes revealed the presence of fluorescence transients that were synchronized with the electrical activity recorded from hindlimb muscle nerves. Optical imaging was also used to demonstrate the rhythmic activity of a population of interneurones that is believed to provide some of the excitatory drive to motoneurones. Calcium transients were synchronized between motoneurones and these interneurones. Whole cell recordings from interneurones around the lateral motor column confirmed the optical findings and showed that many interneurones receive rhythmic synaptic drive in phase with that of motoneurones. Dye injections into individual interneurones failed to demonstrate the existence of widespread dye-coupling implying that synaptic mechanisms are responsible for the widespread synchrony in the activity of embryonic spinal neurones.
KeywordsRhythmic Activity Ventral Root Transverse Face Neuroscience Method Synaptic Drive
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