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|Body; Ventral Cord||
(C. elegans book II CSHL Press, 1997.Rand J.B. and Nonet M.L. Appendix II: Neurotransmitter assignments for specific neurons)(Eastman C.L. et al. 1999)
GABAergic inhibitory ventral cord motor neurons. DD's receive dyadic synapses from excitatory ventral cord motor neurons along with body wall muscles. The initial pattern of synapses made by DD neurons are presynaptic and inhibitory to ventral body wall muscles while being postsynaptic to neurons that activate dorsal body wall muscles. During late L1, after the birth of VD motor neurons, DD neurons change their synaptic pattern such that their dorsal branches become presynaptic and inhibitory to dorsal body wall muscles while their ventral branches become postsynaptic to excitatory neurons that synapse on ventral body wall muscles (White J. G. et al, 1978; Walthall W. W. et al, 1993). Hermaphrodites and males exhibit some differences in DDn connectivity.
Functions: Sinusoidal body movement. DD's receive input from VA and VB neurons, and hence, are likely to be active during ventral muscle contractions. They form neuromuscular junctions dorsally that coordinately relax the dorsal muscles during ventral muscle contraction (Driscoll M. and Kaplan J., 1997). D-type neurons may also regulate the wave amplitude of the sinusoidal movement since unc-25 and unc-30 mutants that lack functional D neurons generate rhythmic sinusoidal movement with a reduced amplitude (McIntire S. L. et al, 1993)
Receptor expression: Express neuropeptide Y receptor like protein, NPR-1 (Coates J. C. and de Bono M., 2002; Wang Q and Wadsworth W. G., 2002). Suggested to express GABA-A/glycine receptor-like protein GGR-2 (Fujiwara et al, 1996). Express UNC-8, a DEG/ENaC family member homologous to subunits of a candidate mechanically gated ion channel (Tavernarakis N. et al, 1997).
Male Wiring Project
Note: In males, the DD6 cell body lies posterior to the male-specific CP9 neuron, which defines the anterior boundary of the male pre-anal ganglion (see Male Tail Cell ID). In males, DD6 is therefore considered part of the pre-anal ganglion rather than the ventral nerve cord.
For Male Wiring Project details see "Connectivity" link in Emmons lab website.
Schematic Diagrams of Ventral Cord motor neurons:
|AS neurons||DA and DB neurons||VA neurons|
|VB neurons||VC neurons||DD and VD neurons|
In all diagrams,axon processes with neuromuscular synapses (NMJ) are shown as whereas dendritic processes where synaptic inputs are received are shown as .
Class A axons run forward in both cords (VNC and DC) whereas the class B axons run backwards. The dendritic branches of the dorsal and ventral class A neurons run in opposite directions as do those from class Bneurons. Ventral class D neurons receive their synaptic input on the dorsal side and give NMJ's on the ventral side. The dorsal type D neurons have half the periodicity of their ventral counterparts and receive synapses on the ventral side and give NMJ's on the dorsal side. Class AS neurons only synapse on the dorsal side and have no ventral counterpart, whereas, the class C neurons only synapse on the ventral side. The synapses from class C motor neurons onto body muscles are less dense than for the other classes (White J. et al, 1976)