Little is known about the way in which animals far from home use familiar landmarks to guide their homeward path. Desert ants, Cataglyphis spp., which forage individually over long distances are beginning to provide some answers. We find that ants running 30 m from a feeding place to their nest memorise the visual characteristics of prominent landmarks which lie close to their path. Although remembered visual features are used for identifying a landmark and for deciding whether to go to its left or right, they are not responsible for the detailed steering of an ant's path. The form of the trajectory as an ant approaches and detours around a landmark seems to be controlled by the latter's immediate retinal size; the larger it is, the greater the ant's turning velocity away from the landmark.
Bees of several genera make foraging trips on * Permanent address:Correspondence to: T.S. Collett compartment, but chose the vertical stimulus in the last compartment. Bees reaching a compartment are thus primed to recall the stimulus which they normally encounter there.We argue that the elements which are linked together to form a route are "path-segments", each of which takes a bee for a given distance in a given direction.
Advanced mammalian visual systems can recognize a familiar shape under a variety of viewing conditions. Recognition is possible whether the shape is presented in simple outline, as a random dot stereogram, or by motion contrast. We report here that bees have a similar ability: they can recognize a shape when it is learned through visual signals of one kind and subsequently viewed through another. The results reveal that (i) bees that have learned a shape defined in terms of luminance contrast can recognize the same shape when it is defined in terms of motion contrast, (ii) shapes that are delineated by motion contrast are discriminated through a channel that receives input only from the green photoreceptors, (iii) a shape learned through one class of signal is subsequently recognized via any of these other classes, and (iv) shape is memorized in a generic form regardless of whether it is initially sensed by green-contrast, blue-contrast, luminance-contrast, or motion-contrast signals.To investigate whether bees encode shape in a generic form, regardless of input channel, we began by asking if bees that have learned a shape defined in terms of luminance contrast can recognize the same shape when it is defined in terms of motion contrast. Using a Y maze (Fig. la), we first trained bees to distinguish a ring from a disk, each presented as a black figure against a white background. These shapes are defined in terms of the luminance contrast at their boundaries. The bees learned to make this discrimination well (Fig. lb). We then asked whether these trained bees can distinguish between the same shapes when they are presented as textured figures, 6 cm in front of a similarly textured background. The textured shapes can only be detected through the apparent relative motion or motion contrast between the figure and background as the bee moves relative to them. The bees trained on the "solid" shapes are, indeed, immediately able to distinguish between the textured versions of these shapes (Fig. lc). Thus, bees that have learned a shape that is defined by luminance contrast will recognize the same shape when it is defined by motion contrast. Importantly, bees cannot be trained directly to distinguish between shapes that are defined purely by motion contrast: they need to be "primed" by prior training on luminance-contrast versions of the same shapes (2). After the two-stage training, on the other hand, bees can even distinguish between novel shapes that are defined purely by motion contrast. Thus, after training as in Fig. 1 b and c, the same bees can learn to distinguish between a textured pair of differently oriented oblique bars, which they had never previously encountered (Fig. ld). Evidently, in transferring from the solid ring and disc to the textured versions of the same shapes, the bees learned that motion contrast carries the relevant cues for distinguishing the stimuli. They then used information transmitted through motion contrast to discriminate the novel textured shapes in Fig. ld. Experiments of th...
Wood ants, like other central place foragers, rely on route memories to guide them to and from a reliable food source. They use visual memories of the surrounding scene and probably compass information to control their direction. Do they also remember the length of their route and do they link memories of direction and distance? To answer these questions, we trained wood ant (Formica rufa) foragers in a channel to perform either a single short foraging route or two foraging routes in opposite directions. By shifting the starting position of the route within the channel, but keeping the direction and distance fixed, we tried to ensure that the ants would rely upon vector memories rather than visual memories to decide when to stop. The homeward memories that the ants formed were revealed by placing fed or unfed ants directly into a channel and assessing the direction and distance that they walked without prior performance of the food-ward leg of the journey. This procedure prevented the distance and direction walked being affected by a home vector derived from path integration. Ants that were unfed walked in the feeder direction. Fed ants walked in the opposite direction for a distance related to the separation between start and feeder. Vector memories of a return route can thus be primed by the ants' feeding state and expressed even when the ants have not performed the food-ward route. Tests on ants that have acquired two routes indicate that memories of the direction and distance of the return routes are linked, suggesting that they may be encoded by a common neural population within the ant brain.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.