Another thing that you can do with C. elegans is severe a nerve with a laser (so as to only damage the nerve and not the whole worm) and then watch the nerve grow back. For instance, in this image from Dr. Bastiani’s lab at UCSD [found here], you can see the typical neuron connecting the ventral and dorsal nerve cords in the top image with I believe the arrow pointing to where the laser will sever the neuron. Then in the second image, you can see the neuron trying to grow back unsuccessfully. If scientists can discover how to make these nerves grow back successfully, this could help people who are paralyzed, as we could then possibly recreate this neurogenesis and repair in spinal cord injury. Of course, my explanation is simplified and there are a number of factors that would go into making nerves regenerate and reconnect, but this is the general idea.