Developmental trajectory of Caenorhabditis elegans nervous system governs its structural organization
Fig 4
Birth times and lineage distances constrain connections between neurons whose cell bodies are spatially distant from each other.
(A-B) The mean birth time of synaptically connected pairs of neurons exhibit a trimodal distribution, with connections clustering into three temporal groups corresponding to those (i) between neurons that are both born early, i.e., in the embryonic stage, (ii) between one born early and the other born late (i.e., in the post-embryonic stage), and (iii) between neurons that are both born late. The hatching time ht separating the embryonic from other developmental stages is indicated by the broken line. We note from panel (A) that when both neurons are born late (corresponding to the uppermost cluster of connections), synaptic connections are more likely to occur between neurons whose cell bodies are located close to each other. (C-D) Synaptic connections between neurons that are closely related to each other in terms of lineage (l < 10) occur almost always when their cell bodies are in proximity, regardless of the time of birth of the neurons. We note that this restriction is more pronounced than observed in Fig 2(E), where P(D, l) shows a prominent peak at the lower end of D for small l suggesting that most closely related neurons (whether connected or not) typically have short distances between their cell bodies. (E-H) Neurons connected by gap junctions show patterns similar to those seen in the case of synaptic connections.