Cover legend: Cross-section of a lamprey spinal cord highlighting the large size of the giant reticulospinal axons in the ventromedial tract. When the spinal cord is inverted, the giant axons become accessible for microinjections, allowing perturbation of any presynaptic protein of interest. Giant axons are immunostained with a mouse monoclonal antibody made against lamprey neurofilament-180 (kind gift of Dr. Michael E. Selzer). Punctate staining pattern represents synapses, immunostained with an antibody against synuclein (Abcam 53726). Nuclei of cells in the central canal and motor neurons are labeled with ProLong® Gold (Life Sciences/Invitrogen). Cover photo made by students in the Brown-MBL NeuroPracticum course (Saba Baskolyu, Tory McLean, Alissa Trepman), Susan M. Banks, and Jennifer R. Morgan. For more information see Morgan et al. (pages 8009–8021).