Spatial vision in insects is facilitated by shaping the dynamics of visual input through behavioral action

Abstract

Insects such as flies or bees, with their miniature brains, are able to control highly aerobatic flight maneuvres and to solve spatial vision tasks, such as avoiding collisions with obstacles, landing on objects, or even localizing a previously learnt inconspicuous goal on the basis of environmental cues. With regard to solving such spatial tasks, these insects still outperform man-made autonomous flying systems. To accomplish their extraordinary performance, flies and bees have been shown by their characteristic behavioral actions to actively shape the dynamics of the image flow on their eyes (“optic flow”). The neural processing of information about the spatial layout of the environment is greatly facilitated by segregating the rotational from the translational optic flow component through a saccadic flight and gaze strategy. This active vision strategy thus enables the nervous system to solve apparently complex spatial vision tasks in a particularly efficient and parsimonious way. The key idea of this review is that biological agents, such as flies or bees, acquire at least part of their strength as autonomous systems through active interactions with their environment and not by simply processing passively gained information about the world. These agent-environment interactions lead to adaptive behavior in surroundings of a wide range of complexity. Animals with even tiny brains, such as insects, are capable of performing extraordinarily well in their behavioral contexts by making optimal use of the closed action–perception loop. Model simulations and robotic implementations show that the smart biological mechanisms of motion computation and visually-guided flight control might be helpful to find technical solutions, for example, when designing micro air vehicles carrying a miniaturized, low-weight on-board processor.

Cockroach optomotor responses below single photon level

“…This indicates pooling (here: spatial summation) of 6-20 photoreceptors to one second-order cell at the first stage of processing (Ribi, 1977). However, in darkness, more spatial summation is generally required at higher stages to create a signal, with which a movement detector could operate (Borst et al, 2010;Egelhaaf et al, 2012). In nocturnal bees the optimal spatial summation, both with high stimulus velocities and low light intensities, requires a recruitment of 12 to 30 s order units (lamina cartridges) at the lowest intensity tested (Theobald et al, 2006).…”

Head movements and the optic flow generated during the learning flights of bumblebees

“…Insects, which have their eyes positioned close together, generally rely on motion parallax for 3D scene analysis and often eliminate rotational optic flow (reviewed in Egelhaaf et al, 2012). Rotational optic flow carries little useful information about the structure of the world when the rotating observer is positioned at the centre of rotation and sees the images of objects at all distances rotating at the same speed.…”

Scene perception and the visual control of travel direction in navigating wood ants

“…Insects have an array of visuo-motor control systems for moving effectively within cluttered surroundings [1,2]. Flies separate image motion caused by their own movements through a stationary environment from the image motion generated by other moving objects [3], and use the former for controlling their direction of flight [4] or for landing on surfaces [5] and the latter to pursue potential prey or mates [6,7] or to avoid possible threats [8].…”