Nonlinear integration of sensory inputs and behavioral state by a single neuron in C. elegans.

Context is important for sensory integration; however, explicitly modeling this property as a function of precise presynaptic inputs is not trivial. In Caenorhabditis elegans, the paired interneurons AIBL and AIBR (AIB) integrate both sensory and motor information and strongly drive reversal behavior. Through a series of experiments to monitor reversal behavior and manipulate sensory input onto AIB, we find that while AIB activity is primarily a convolution of behavioral state, its sensory responses are not integrated independently. Instead, the gain in sensory input increases during the transition to the reversal state. Sensory information therefore reinforces the decision to reverse. Context-dependent behavioral responses to sensory input are well-documented. Here, we show this property can be localized to single neurons in the nematode nervous system. This integration property likely plays an important role in context-dependent decision-making, as well as the highly variable dynamics of the C. elegans nervous system.