Complex sentence: He has made important contributions on the synaptic organization of the brain, and his lab at Yale focuses on olfaction, at the level of dendrites, dendritic spines, and synapses, mostly in the olfactory bulb.
Split into simpler sentences: He has made important contributions on the synaptic organization of the brain. His current research focuses on olfaction, at the level of dendrites, dendritic spines, and synapses, mostly in the olfactory bulb.