Zhen Lab

Connectomics 

We are performing semi-automated reconstruction of the wiring diagram, or connectome by serial-section EM of individuals.

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At birth, C. elegans has 218 neurons. 82 new neurons are incorporated before the end of larval development. These include sensory, motor, and interneurons that are located throughout the body, suggesting a system-wide remodeling of the juvenile circuit during post-embryonic development. 

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Combining partial reconstruction data of more than five different isogenic individuals, an adult connectome was mapped more than 30 years ago (The Mind of a Worm, 1986). This map served as the guide for the adult circuit functional interrogation, but is insufficient on its own to address how the circuit develops and varies among individuals.

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Newly emergent technologies improve the fidelity and throughput of serial EM. With the Samuel and Lichtman groups, we have built a pipeline to reconstruct and compare the entire C. elegans nervous system across different developmental time points.

This evolving dataset

• provides answers to how anatomic remodeling takes place without interfering the circuit function

• serves as a framework to interrogate circuit underlying of sensorimotor behaviors during development.

Traces of all neurons, glia, and muscle cells entering the brain (nerve ring) of a first-stage larva, annotated using CATMAID.

In collaboration with the Samuel and Lichtman groups, we are mapping the wiring of the entire nervous system, from hatching to adulthood. This evolving dataset: a) provides answers to how anatomic remodeling takes place without interfering the circuit function; b) serves as a framework to interrogate circuit underlying of sensorimotor behaviors during development.

Individual L1 to Adult

Part of a scanning electron micrograph highlighting synapses in the brain (nerve ring) of a first-stage larva. Imaged by James Mitchell, the Samuel Lab.

The 3D model of a motor neuron pair undergoing remodeling

(16hr after hatching)