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Mechanisms of excitation of spinal networks by stimulation of the ventral roots
Author(s) -
O’Donovan Michael J.,
Bonnot Agnes,
Mentis George Z.,
Chub Nikolai,
Pujala Avinash,
Alvarez Francisco J.
Publication year - 2010
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1111/j.1749-6632.2010.05535.x
Subject(s) - excitatory postsynaptic potential , neuroscience , stimulation , spinal cord , chemistry , biology , inhibitory postsynaptic potential
It has recently been demonstrated that motoneurons in neonatal rodents release an excitatory amino acid, in addition to acetylcholine, from their central terminals onto Renshaw cells. Although the function of this amino acid release is not understood, it may mediate the excitatory actions of motor axon stimulation on spinal motor networks. Stimulation of motor axons in the ventral roots or muscle nerves can activate the locomotor central pattern generator or entrain bursting in the disinhibited cord. Both of these effects persist in the presence of cholinergic antagonists and are abolished or diminished by ionotropic and metabotropic glutamate antagonists. Calcium imaging in the disinhibited cord shows that a ventral root stimulus evokes ventrolateral activity initially, which subsequently propagates to the rest of the cord. This finding suggests that excitatory interneurons excited by motoneuron recurrent collaterals are located in this region. However, motoneurons do not exhibit short latency excitatory potentials in response to ventral root stimulation indicating that the excitatory effects are mediated polysynaptically. We discuss the significance of these findings.

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