Disclosed are methods and compositions for maintaining neural pathways in a mammal including: enhancing survival of neurons at risk of dying; inducing cellular repair of damaged neurons and neural pathways; stimulating neurons to maintain their differentiated phenotype; and promoting dendritic outgrowth, including maintaining dendritic arbors and regenerating dendritic architecture. In one embodiment, the invention provides means for stimulating CAM expression in neurons. The invention also provides means for evaluating the status of nerve tissue, including means for detecting and monitoring neuropathies in a mammal. The methods, devices and compositions include a morphogen or morphogen-stimulating agent provided to the mammal in a therapeutically effective concentration. In another embodiment, the invention provides methods and compositions which include a morphogen or morphogen-stimulating agent, and a nerve trophic factor or nerve trophic factor-stimulating agent at concentrations effective for stimulating dendrite outgrowth. The morphogen and the nerve trophic factor can be admixed in combination.