Our brains can process the same sensory cues very differently based on past experience (i.e. learning and memory) or current context. Our goal is to understand this process at the levels of synaptic plasticity, neural circuit and behavior. Our model system is a simple brain of the fruit fly, Drosophila. We employ in vivo electrophysiology and two-photon calcium imaging together with genetic circuit manipulation. Taking advantage of this unique combination, we aim to find important circuit principles that are shared with vertebrate systems.