High-throughput optical quantification of mechanosensory habituation reveals neurons encoding memory in Caenorhabditis elegans.

A major goal of neuroscience studies is to identify the neurons and molecules responsible for memory. Mechanosensory habituation in Caenorhabditis elegans is a simple form of learning and memory, in which a circuit of several sensory neurons and interneurons governs behavior. However, despite the usefulness of this paradigm, there are hardly any systems for rapid and accurate behavioral genetic analysis. Here, we developed a multiplexed optical system to genetically analyze C. elegans mechanosensory habituation, and identified two interneurons involved in memory formation. The system automatically trains large populations of animals and simultaneously quantifies the behaviors of various strains by optically discriminating between transgenic and nontransgenic animals. Biochemical and cell-specific behavioral analyses indicated that phosphorylation of cyclic AMP response element-binding protein (CREB), a factor known to regulate memory allocation, was facilitated during training and this phosphorylation in AVA and AVD interneurons was required for habituation. These interneurons are a potential target for cell-specific exploration of the molecular substrates of memory.