Perception of aerodynamical looming stimuli

An approaching predator generates a distinct temporal sensory signature, a looming stimulus, alerting a prey. Although the mechanisms for visual looming detection have been thoroughly investigated, those associated with aerodynamic looming- air movements induced by an approaching predator-remain largely unexamined. Given that both types of looming involve a non-linear increase in certain signal characteristics with decreasing distance, we tested whether the mechanisms of perception of aerodynamic looming are analogous with those of visual perception. We stimulated the cercal system of the cricket Acheta domesticus, a well-established model for airflow sensing, with spider-mimicking translating spheres. The size and velocity of the looming object, the two critical parameters in visual looming perception, significantly enhanced the activity of wind-sensitive interneurons and the escape reaction. Moreover, the timing of peak firing occurred after a small delay after crossing a flow threshold, a physiological property typical of visual looming-sensitive neurons. These findings suggest the existence of convergent computational principles of looming detection across different sensory modalities.