The ability to quickly maneuver through a variety of environments requires a central nervous system that can rapidly transfer sensory and motor signals. The neck connective, a bottleneck in the information traveling from the brain to the thorax, is being sectioned and imaged using transmission electron microscopy. These incredibly high resolution images show that, among other things, neck axons in Manduca sexta are ensheathed by highly layered glial cells, similar in appearance to the myelin sheaths of vertebrates. Currently, we are running electrophysiology experiments to measure the conduction velocities of giant fibers in the neck connective in order to determine whether these ensheathing structures function similarly to myelin sheaths. In addition to creating a map of the giant fibers in the hawkmoth nerve cord, these findings will provide insight into the convergent evolution of ensheathed neurons in animals.
