23. Young and MacDonald. (1983) .

NeuronCompartmentPropertyConnectivityNotes
Spinal cord L motor neuron alphaProximal equivalent dendriteAMPAIa afferents release GLUGlu from Ia axon terminals (reviewed in Young and MacDonald, 198323 ). Intracellular recordings: CMQX and NBQX applied at the soma completely block short duration (i.e. near soma) single fiber EPSPs (Walmsley B and Bolton PS, 1994 [cat ]21 ; see Burke 1998 for references). Single-fiber Ia EPSPs have widely varying shapes (KUNO M, 196461 ; Burke RE, 196762 ; Jack JJ et al, 197163 ; Mendell LM and Henneman E, 197164 ), indicating that Ia synapses are distributed widely over soma-dendrites (confirmed by HRP labelling of Ia afferents on labelled motoneurones: reviewed in Burke RE and Glenn LL, 1996 [cat ]65 , SOBiv p88). Glutamate is released from Ia terminals (Krnjevic K, 198166 ; Puil E, 198367 ). Ia synapses are immunoreactive for GLU (Maxwell DJ et al, 1990 [cat ]68 ). Ia EPSPs are mediated largely by AMPA receptors (muscle afferents: Jahr CE and Yoshioka K, 1986 [rat ]69 ; single fiber EPSPs: Walmsley B and Bolton PS, 1994 [cat ]21 ); by contrast, Pinco M and Lev-Tov A, 1993 [rat ]22 found an NMDA component in neonatal rat. Short-term post-tetanic potentiation (PTP) and depression (PTD) occur (CURTIS DR and ECCLES JC, 196070 ), but not LTP or LTD (SOBiv p90).
Spinal cord L motor neuron alphaProximal equivalent dendriteGlycineIa interneurons release GLYGlycine from some Renshaw interneurons; IPSPs are Cl- mediated, potentially blocked by strychnine (Cullheim S and Kellerth JO, 1981 [cat ]26 ). Ia IPSPs are chloride mediated (Coombs, 195229 ); blocked by strychnine. Ia IPSPs are located near the cell soma (Burke RE et al, 1971 [cat ]60 ; reviewed in Young and MacDonald, 198323 ). Ia IPSPs are readily affected by soma current or Cl- injection, indicating location at the soma or proximal dendrites (Burke RE et al, 1971 [cat ]60 , SOBiv p94). Glycine ionophoresis mimics Ia IPSPs (reviewed by Young and MacDonald, 198323 , SOBiv p94). Ia IPSPs are blocked by strychnine, a known blocker of Glycine receptors (SOBiv p94).
Spinal cord L motor neuron alphaSomaGlycineIa interneurons release GLYGlycine from some Renshaw interneurons; IPSPs are Cl- mediated, potentially blocked by strychnine (Cullheim S and Kellerth JO, 1981 [cat ]26 ). Ia IPSPs are chloride mediated (Coombs, 195229 ); blocked by strychnine. Ia IPSPs are located near the cell soma (Burke RE et al, 1971 [cat ]60 ; reviewed in Young and MacDonald, 198323 ). Ia IPSPs are readily affected by soma current or Cl- injection, indicating location at the soma or proximal dendrites (Burke RE et al, 1971 [cat ]60 , SOBiv p94). Glycine ionophoresis mimics Ia IPSPs (reviewed by Young and MacDonald, 198323 , SOBiv p94). Ia IPSPs are blocked by strychnine, a known blocker of Glycine receptors (SOBiv p94).
Spinal cord L motor neuron alphaSomaGlutamate-----Glu from Ia axon terminals (reviewed in Young and MacDonald, 198323 ).
Spinal cord L motor neuron alphaSomaAMPAIa afferents release GLUGlu from Ia axon terminals (reviewed in Young and MacDonald, 198323 ). Intracellular recordings: CMQX and NBQX applied at the soma completely block short duration (i.e. near soma) single fiber EPSPs (Walmsley B and Bolton PS, 1994 [cat ]21 ; see Burke 1998 for references). Single-fiber Ia EPSPs have widely varying shapes (KUNO M, 196461 ; Burke RE, 196762 ; Jack JJ et al, 197163 ; Mendell LM and Henneman E, 197164 ), indicating that Ia synapses are distributed widely over soma-dendrites (confirmed by HRP labelling of Ia afferents on labelled motoneurones: reviewed in Burke RE and Glenn LL, 1996 [cat ]65 , SOBiv p88). Glutamate is released from Ia terminals (Krnjevic K, 198166 ; Puil E, 198367 ). Ia synapses are immunoreactive for GLU (Maxwell DJ et al, 1990 [cat ]68 ). Ia EPSPs are mediated largely by AMPA receptors (muscle afferents: Jahr CE and Yoshioka K, 1986 [rat ]69 ; single fiber EPSPs: Walmsley B and Bolton PS, 1994 [cat ]21 ); by contrast, Pinco M and Lev-Tov A, 1993 [rat ]22 found an NMDA component in neonatal rat. Short-term post-tetanic potentiation (PTP) and depression (PTD) occur (CURTIS DR and ECCLES JC, 196070 ), but not LTP or LTD (SOBiv p90). Motoneurons have a high density of AMPA receptors (Vandenberghe et al, JNS 20: 7158, 2000). There is evidence that "glutamate receptor-mediated Ca2+ influx, intracellular Ca2+ accumulation, and subsequent cell death" may be involved in the mechanism of selective motoneuron degeneration in amyotrophic lateral sclerosis.
Spinal cord L motor neuron alphaSomaNMDAIa afferents release GLUGlu from Ia axon terminals (reviewed in Young and MacDonald, 198323 ; Pinco M and Lev-Tov A, 1993 [rat ]22 ). Single-fiber Ia EPSPs have widely varying shapes (KUNO M, 196461 ; Burke RE, 196762 ; Jack JJ et al, 197163 ; Mendell LM and Henneman E, 197164 ), indicating that Ia synapses are distributed widely over soma-dendrites (confirmed by HRP labelling of Ia afferents on labelled motoneurones: reviewed in Burke RE and Glenn LL, 1996 [cat ]65 , SOBiv p88). Glutamate is released from Ia terminals (Krnjevic K, 198166 ; Puil E, 198367 ). Ia synapses are immunoreactive for GLU (Maxwell DJ et al, 1990 [cat ]68 ). Ia EPSPs are mediated largely by AMPA receptors (muscle afferents: Jahr CE and Yoshioka K, 1986 [rat ]69 ; single fiber EPSPs: Walmsley B and Bolton PS, 1994 [cat ]21 ); by contrast, Pinco M and Lev-Tov A, 1993 [rat ]22 found an NMDA component in neonatal rat. Short-term post-tetanic potentiation (PTP) and depression (PTD) occur (CURTIS DR and ECCLES JC, 196070 ), but not LTP or LTD (SOBiv p90). Postnatal development and properties of these receptors were studied with whole-cell and outside-out patch-clamp. The conductance and relative distribution were independent of age from postnatal day 4 to 14. The results also suggested that their properties differ from those in spinal cord interneurons (Palecek JI et al, 1999 [rat ]282 ).
Spinal cord L motor neuron alphaProximal equivalent dendriteNMDAIa afferents release GLUGlu from Ia axon terminals (reviewed in Young and MacDonald, 198323 ; Pinco M and Lev-Tov A, 1993 [rat ]22 ). Single-fiber Ia EPSPs have widely varying shapes (KUNO M, 196461 ; Burke RE, 196762 ; Jack JJ et al, 197163 ; Mendell LM and Henneman E, 197164 ), indicating that Ia synapses are distributed widely over soma-dendrites (confirmed by HRP labelling of Ia afferents on labelled motoneurones: reviewed in Burke RE and Glenn LL, 1996 [cat ]65 , SOBiv p88). Glutamate is released from Ia terminals (Krnjevic K, 198166 ; Puil E, 198367 ). Ia synapses are immunoreactive for GLU (Maxwell DJ et al, 1990 [cat ]68 ). Ia EPSPs are mediated largely by AMPA receptors (muscle afferents: Jahr CE and Yoshioka K, 1986 [rat ]69 ; single fiber EPSPs: Walmsley B and Bolton PS, 1994 [cat ]21 ); by contrast, Pinco M and Lev-Tov A, 1993 [rat ]22 found an NMDA component in neonatal rat. Short-term post-tetanic potentiation (PTP) and depression (PTD) occur (CURTIS DR and ECCLES JC, 196070 ), but not LTP or LTD (SOBiv p90).
Spinal cord L Interneuron 1aAxon terminalGlycineMotoneuron: soma and DepGLY ionophoresis mimics Ia IPSPs (reviewed by Young and MacDonald, 198323 ) SOBiv p95.

References
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