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NMDA Receptor‐mediated Oscillatory Properties: Potential Role in Rhythm Generation in the Mammalian Spinal Cord
Author(s) -
SCHMIDT BRIAN J.,
HOCHMAN SHAWN,
MacLEAN JASON N.
Publication year - 1998
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.1749-6632.1998.tb09049.x
Subject(s) - nmda receptor , neuroscience , spinal cord , context (archaeology) , biology , membrane potential , chemistry , receptor , biochemistry , paleontology
A bstract : Previous studies have demonstrated that (1) NMDA receptor activation occurs during locomotor network operation in lower and higher vertebrates and (2) NMDA induces active membrane properties that can be expressed as intrinsic voltage fluctuations in cells located in the spinal cord of lower vertebrates, as well as in neurons located in supraspinal regions of the mammalian nervous system. This paper reviews recent data showing that NMDA can induce similiar inherent membrane potential behavior in synaptically isolated motoneurons and interneurons in the mammalian ( in vitro neonatal rat) spinal cord. These TTX‐resistant voltage fluctuations include rhythmic oscillations and plateau potentials, as well as low‐frequency long‐lasting voltage shifts (LLVSs). 5‐HT facilitates the transformation of LLVSs into oscillatory events, and 5‐HT receptor antagonists have the reverse effect. In the absence of TTX, locomotor‐related rhythmic drive potentials in spinal cord neurons can display nonlinear voltage behavior compatible with NMDA receptor activation, although other voltage‐activated conductances are not excluded. Suppression of the nonlinear voltage response associated with NMDA receptor activation, via removal of Mg 2+ , disrupts locomotor patterns of network activity. The potential role of NMDA receptor activation in the operation of mammalian locomotor networks is discussed in the context of these recent observations.