Paul Katz has been awarded a $3.1 million grant from the National Institute of Neurological Disease and Stroke to study how new neurons are added to functional neural circuits. Many neurological conditions result from problems arising during development, yet a fundamental understanding of how new neurons are added to growing circuits is lacking. The project, which is in collaboration with researchers at Harvard University, takes advantage of an unusual research subject, a nudibranch mollusc. This sea slug increases the number of neurons in its brain over 40 fold in less than eight weeks, while it continues to perform behaviors. The Katz lab and their collaborators plan to map all of the neurons and their connections (the connectome) as new neurons are added by cutting the brains of animals at different ages into very thin slices, imaging them in an electron microscope, and then reconstructing all of the neurons and their connections. This massive undertaking will require new methods in machine learning to classify neurons and synapses across samples. The results will provide an unprecedented look at how the synaptic networks of neurons across an entire brain change as new neurons are added. Katz is a Professor in the Department of Biology and the Director of the UMass Initiative on Neurosciences. His lab also receives funding from the National Science Foundation.