RT Journal Article SR Electronic T1 A gate-and-switch model for head orientation behaviors in C. elegans JF eneuro JO eNeuro FD Society for Neuroscience SP ENEURO.0121-18.2018 DO 10.1523/ENEURO.0121-18.2018 A1 Marie-Hélène Ouellette A1 Melanie J. Desrochers A1 Ioana Gheta A1 Ryan Ramos A1 Michael Hendricks YR 2018 UL http://www.eneuro.org/content/early/2018/11/20/ENEURO.0121-18.2018.abstract AB The nervous system seamlessly integrates perception and action. This ability is essential for stable representation of and appropriate responses to the external environment. How the sensorimotor integration underlying this ability occurs at the level of individual neurons is of keen interest. In C. elegans, RIA interneurons receive input from sensory pathways and have reciprocal connections with head motor neurons. RIA simultaneously encodes both head orientation and sensory stimuli, which may allow it to integrate these two signals to detect the spatial distribution of stimuli across head sweeps and generate directional head responses. Here, we show that blocking synaptic release from RIA disrupts head orientation behaviors in response to unilaterally presented stimuli. We found that sensory encoding in RIA is gated according to head orientation. This dependence on head orientation is independent of motor encoding in RIA, suggesting a second, posture-dependent pathway upstream of RIA. This gating mechanism may allow RIA to selectively attend to stimuli that are asymmetric across head sweeps. Attractive odor removal during head bends triggers rapid head withdrawal in the opposite direction. Unlike sensory encoding, this directional response is dependent on motor inputs to and synaptic output from RIA. Together, these results suggest that RIA is part of a sensorimotor pathway that is dynamically regulated according to head orientation at two levels: the first is a gate that filters sensory representations in RIA, and the second is a switch that routes RIA synaptic output to dorsal or ventral head motor neurons.Significance statement Simple head orientation behaviors in C. elegans provide an opportunity to dissect sensorimotor integration at the cellular and subcellular levels. We describe a single interneuron that coordinates posture, sensation, and movement to detect the spatial distribution of stimuli and direct motor output to guide navigation behavior. Our findings underscore the fundamental role of neural mechanisms for integrating sensory input into ongoing behavior.