The astonishing capacity of the brain to process and store information crucially relies on properly functioning synapses. They provide the connecting entities within neural circuits and they properties define circuit function. The molecular composition of synapses can be very different, which has not been appreciated yet to the extent that would allow deeper insights into the molecular underpinnings of information processing in different circuits. While the role of proteins, as core components of the synaptic cell membrane and synaptic transmission has been addressed in certain detail it is unclear to what extent the molecular diversity of lipids can influence synaptic function. Based on new technologies allowing for the first time lipidomic studies at the level of different synapse types, the project aims at unveiling the molecular interactions between lipids and proteins. Newly developed analysis strategies as well as innovative lipid tagging and imaging approaches will enable us to determine the membrane composition of specific synapses with high resolution. This will pave the way to studies on how aging and neurological diseases influence synaptic lipid composition and affect signaling with the prospect of therapeutic interventions.