What are the physical underpinnings of long lasting memory? How does experience instantiate itself into the structure of neural circuits? How do brain circuits change as a brain goes from infancy to adulthood? 

The Lichtman lab develops and applies advanced imaging approaches to map neural connections and understand their development, so that we may be better poised to address these big mysteries of brain science. During mammalian development, synaptic connectivity changes dramatically as axons trim many of the synaptic branches and target cells loose many of their synaptic partners while at the same time the subset of connections that remain become stronger. It is possible that these changes underlie the way experience selects from a broad range of synaptic connections a small subset to underlie a long lasting trace of an experience. Our work argues that competition between the neurons that co-innervate the same target cells in development may drive these changes in connectivity. The lab studies circuit formation and rearrangement by visualizing peripheral (motor and autonomic) synaptic circuits directly in living animals. These studies take advantage of transgenic animals in which we express different colored fluorescent proteins in each cell (Brainbow). In addition we have developed automated tools to map neural connections (connectomics) at nanometer resolution using a new method of serial electron microscopy. This latter approach gives of a means of revealing neural circuit motifs throughout the nervous system.