Craig Bailey, PhD

Our primary interest is the analysis of behaviorally relevant structural plasticity as it occurs at the level of identified synapses. Toward that end, we have extensively studied the storage of long-term memory for sensitization of the gill-withdrawal reflex in Aplysia and have found that it is associated with the growth of new synapses by the sensory neurons onto their postsynaptic target neurons. Despite the association of synaptic growth with various forms of long-term memory, surprisingly little is known about the cell biological mechanisms that regulate and couple the structural changes to the molecular changes that govern learning-induced synaptic plasticity and the relative functional contribution each may make to the initiation of the long-term process on the one hand and its stable maintenance on the other.

To address these questions, we have combined time-lapse imaging and molecular biological analysis (using gene transfer) of living sensory-to-motor neuron synapses in culture and have monitored both functional and structural changes simultaneously so as to follow remodeling and growth at the same specific synaptic connections continuously over time. This approach has allowed us to examine directly the functional contribution of learning-related structural changes to the different time-dependent phases of memory storage. Insights provided by these studies suggest the synaptic differentiation and growth induced by learning in the mature nervous system are highly dynamic and often rapid processes that can recruit both molecules and mechanisms important for de novo synapse formation during development.