Behavioral Plasticity in the C. elegans Mechanosensory Circuit.

This review outlines research into the cellular and molecular mechanisms underlying a simple behavior in the soil-dwelling nematode, C. elegans. A tap administered to the side of a petri plate acts as a nonlocalized mechanical stimulus to the worms within. Most adult worms respond to this tap stimulus with backward locomotion, an action known as the tap-withdrawal response. This behavior has been thoroughly characterized and the neural circuit mediating it has been determined. The response habituates following repeated stimulation, and current work is aimed at elucidating the mechanism behind this simple form of nonassociative learning. Changes in cell excitability and the strength of glutamatergic synapses play key roles in mediating this plasticity.