Understanding the biology behind brain development, learning, and behavior poses many challenges in neuroscience with many brain regions, neuronal networks, and specific neuronal populations to consider. To tease apart how different neurons impact a certain output, neuroscientists have begun to use more precise genetic tools: activators, inhibitors, sensors, recombinases, and more. With the help of adeno-associated viral vectors (AAV), neuroscientists can combine classical genetic tools with the manipulation of specific neuronal subtypes and determine how these changes affect the phenotype. Viral vectors and genetic approaches are continuously refined and developed so there are many combinations to choose from for your experiments!