ERM was born in San Juan, Argentina in 1943, and immigrated with his family to the USA in 1956. He become a U.S. citizen in 1961. He entered the University of Iowa in 1960 and received a B.A in physics in 1963. While an undergraduate, he worked with the team of Prof. James Van Allen on the early exploration of the Earth's radiation belts. He began graduate studies in the Physics Department at Columbia in 1963, with a NASA fellowship and an interest in astrophysics, but switched to a project involvi ng the use of muonic x-rays to study nuclear structure under Prof. Chien-Shung Wu. After receiving his Ph.D. in 1968, ERM became interested in neurobiology and carried out postdoctoral studies with Prof. Cyrus Levinthal of the Columbia Department of Biol ogical Sciences. During this period he worked on the development of computer-based systems for 3-D reconstruction of neuronal assemblies and on the structure, function and development of the Daphnia visual system. In 1975, he began the work on the devel opment of the medicinal leech nervous system that he continues at present. Currently, his laboratory employs a range of molecular, cellular, anatomical and physiological techniques to investigate target recognition and the genesis of neuronal arbors, con centrating in particular on the functions of signaling molecules such as receptor phosphatases. His research efforts have been continuously funded by NIH and/or NSF since 1974; he also received the recognition of an NIH Javits Investigator award.