Functional diversity from generic encoding in insect campaniform sensilla

Insect proprioception utilizes hundreds of campaniform sensilla embedded in the exoskeleton that sense strain. These sensilla are essential for many behaviors, especially flight control. Despite their role in diverse behaviors, campaniform sensilla share many neural properties. White noise analysis of campaniform sensilla on both lepidopteran wings and dipteran halteres shows selectivity to two stimulus features related by a derivative (derivative pair feature detection, DPFD), which are sufficient to explain spiking activity. DPFD is an inherent property of non-specialized Hodgkin-Huxley dynamics. Nonetheless, DPFD in campaniform sensilla enables simple control laws at multiple timescales. Campaniform sensilla specialization may derive more from stimulus prefiltering by receptor mechanics and anatomical arrangement, although neural specialization may also contribute for more complex, naturalistic stimuli. Evolution may tinker with the placement of these ubiquitous sensors and adapt them to different functions without the encumbrance of particular neural specialization, a strategy potentially useful for engineered walkers and fliers.