If you could pause time for an instant and make yourself small enough to discern individual molecules, the far right of this image is what you might see when one brain cell communicates with another across a synapse—the point of contact between two nerve cells. How the brain senses, thinks, learns and emotes depends on how all its nerve cells, or neurons, communicate with one another. And as a result, many laboratories are working feverishly to understand how synapses function—and how psychiatric drugs, which target them, improve patients’ lives.