An inhibitory acetylcholine receptor gates context-dependent mechanosensory processing in C. elegans

An animal's current behavior influences its response to sensory stimuli, but the molecular and circuit-level mechanisms of this context-dependent decision-making are not well understood. Caenorhabditis elegans are less likely to respond to a mechanosensory stimulus by reversing if the stimuli is received while the animal turns. Inhibitory feedback from turning associated neurons are needed for this gating. But until now, it has remained unknown precisely where in the circuit gating occurs and which specific neurons and receptors receive inhibition from the turning circuitry. Here, we use genetic manipulations, single-cell rescue experiments, and high-throughput closed-loop optogenetic perturbations during behavior to reveal the specific neuron and receptor responsible for receiving inhibition and altering sensorimotor processing. Our measurements show that an inhibitory acetylcholine-gated chloride channel comprising LGC-47 and ACC-1 expressed in neuron type RIM disrupts mechanosensory evoked reversals during turns, presumably in response to inhibitory signals from turning-associated neuron SAA.