Synapses of the central nervous system are highly specialized regions of cell-cell contact designed to rapidly and efficiently relay signals from one neuron to another. By establishing a dynamic yet precise network of synaptic connections, the brain is able to attain a level of functional complexity that enables not only simple motor tasks, but also sophisticated emotional and cognitive behaviour. The study of how synapses form and function is therefore essential to our ultimate understanding of higher brain functions such as learning and memory as well as our understanding of how things go awry in neurodevelopmental and neurodegenerative disorders such as intellectual disabilities, schizophrenia, autism, anxiety disorders, addiction and Alzheimer’s disease.