Useful road maps: studying Drosophila larva’s central nervous system with the help of connectomics

•Drosophila larva enables combining comprehensive synapse resolution connectivity maps with cellular-resolution activity maps and behavior maps.•This approach provides a way to elucidate neural implementation of universal brain computations such as multisensory integration, learning, and action-selection.•Early multisensory convergence recruits specific sensorimotor loops for specific actions.•Higher-order brain areas integrate modalities in a more centralized way and produce high-order, valence-like signals for goal-oriented behavior. The larva of Drosophila melanogaster is emerging as a powerful model system for comprehensive brain-wide understanding of the circuit implementation of neural computations. With an unprecedented amount of tools in hand, including synaptic-resolution connectomics, whole-brain imaging, and genetic tools for selective targeting of single neuron types, it is possible to dissect which circuits and computations are at work behind behaviors that have an interesting level of complexity. Here we present some of the recent advances regarding multisensory integration, learning, and action selection in Drosophila larva.