One of the major research projects in my laboratory focuses on examining the development and regeneration of the mossy fiber pathway, a major axonal pathway in an area of the brain called the hippocampus. The mossy fiber pathway is one of the most dynamic and plastic pathways in the brain. It develops after birth in rodents, and new mossy fibers continue to be produced in mature animals. Mossy fibers are one of the few axonal pathways in the central nervous system that can regenerate their normal synaptic pattern following transection. Our investigation of this system has identified several axon guidance molecules that appear to play a role in the outgrowth and regeneration of mossy fibers. These studies should enhance our understanding of normal mossy fiber development as well as provide new insights into the mechanisms used by mossy fibers to reestablish their normal synaptic pattern following injury.