This is a snapshot of a Monte Carlo simulation of two excitatory hippocampal synapses. Two synapses (presynaptic terminals in green, postsynaptic spines in gray) are separated by abstracted processes of other neurons (gray) and glia (orange). This picture was taken 50 µs after a vesicle containing glutamate (purple particles) was released into the synapse on the left. Work in the lab focuses on determining the extent to which glutamate released at one synapse can spill over into a neighboring synapse, as well as identifying the mechanisms that regulate this spillover. For more information of MCell simulation software, see www.mcell.cnl.salk.edu.