Scene perception and the visual control of travel direction in navigating wood ants (original) (raw)
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The Use of Edges in Visual Navigation by the Ant Leptothorax albipennis
Ethology, 2001
Certain navigating insects home in on their goal by moving so that currently viewed images of landmarks fall on the same retinal locations memorized during previous visits. Here we show that ants can use similar retinotopic learning to guide lengthy routes, by memorizing and walking parallel to a distinct visual edge. We induced workers of the ant Leptothorax albipennis to travel parallel to a prominent wall. When the wall's height was changed, the ants' paths consistently shifted toward a lowered wall and away from a raised wall, as would be expected if they attempt to keep the wall's image at a constant retinal position. These path shifts were smaller than would be expected if the wall was the only guide to navigation, suggesting that other cues are also important. Signi®cantly larger shifts were seen when edge guidance was enhanced by using two walls, one on each side of the path.
On the Encoding of Panoramic Visual Scenes in Navigating Wood Ants
Current Biology, 2016
Highlights d Ants navigating within a panorama composed of two shapes identify each shape d Shapes are identified through their intrinsic visual features d Shapes are also identified through the relative positions of their centers of mass d Ants learn a direction of travel relative to each shape and merge the directions
Visual input and path stabilization in walking ants
Communicative & integrative biology, 2011
Most animals use vision to navigate the outside world. Eyes are the sensory organs for visual perception and can vary in their form, structure and function to suit the visual requirement of the individual species. In insects, mainly the two compound eyes but also the less-conspicuous ocelli are in charge for visual input. Much knowledge has been obtained about compound eyes but little is known about the role of ocelli in walking insects. Recently it has been shown that ant ocelli contribute to encoding celestial compass information for homing. However, ocelli could not compute terrestrial cues for navigating back to the nest. Here we focus on further investigations on the ants' paths stabilization under different visual input conditions. The pitch and roll stabilization of walking paths seems to be independent of visual input and controlled by idiothetic cues. The yaw (meander) stabilisation in walking paths is adjusted for navigational rather than for stabilizing purposes and d...
Models of visually guided routes in ants: Embodiment simplifies route acquisition
2011
It is known that ants learn long visually-guided routes through complex terrain. However, the mechanisms by which visual information is first learnt and then used to control a route direction are not well understood. In this paper we investigate whether a simple approach, involving scanning the environment and moving in the direction that appears most familiar, can provide a model of visually guided route learning in ants. The specific embodiment of an ant's visual system means that movement and viewing direction are tightly coupled, a familiar view specifies a familiar direction of viewing and thus a familiar movement to make. We show the feasibility of our approach as a model of ant-like route acquisition by learning non-trivial routes through a simulated environment firstly using the complete set of views experienced during learning and secondly using an approximation to the distribution of these views.
Route following by one-eyed ants suggests a revised model of normal route following
2020
SummaryThe prevailing account of visually controlled routes is that an ant learns views as it follows a route, while guided by other path-setting mechanisms. Once a set of route views is memorised, the insect follows the route by turning and moving forwards when the view on the retina matches a stored view. We have engineered a situation in which this account cannot suffice in order to discover whether there may be additional components to the performance of routes. One-eyed wood ants were trained to navigate a short route in the laboratory guided by a single black, vertical bar placed in the blinded visual field. Ants thus had to turn away from the route to see the bar. They often turned to look at or beyond the bar and then turned to face in the direction of the goal. Tests in which the bar was shifted to be more peripheral or more frontal than in training produced a corresponding change in the ants’ paths, demonstrating that they were guided by the bar, presumably obtaining infor...
Visual Cues for the Retrieval of Landmark Memories by Navigating Wood Ants
Current Biology, 2007
Background-Even on short routes, ants can be guided by multiple visual memories. We investigate here the cues controlling memory retrieval as wood ants approach a one-or two-edged landmark to collect sucrose at a point along its base. In such tasks, ants store the desired retinal position of landmark edges at several points along their route. They guide subsequent trips by retrieving the appropriate memory and moving to bring the edges in the scene toward the stored positions.
Adaptive Behavior, 2014
The learning walks of ants are an excellent opportunity to study the interaction between brain, body and environment from which adaptive behaviour emerges. Learning walks are a behaviour with the specific function of storing visual information around a goal in order to simplify the computational problem of visual homing, that is, navigation back to a goal. However, it is not known at present why learning walks take the stereotypical shapes they do. Here we investigate how learning-walk form, visual surroundings and the interaction between the two affect homing performance in a range of virtual worlds when using a simple view-based homing algorithm. We show that the ideal form for a learning walk is environment-specific. We also demonstrate that the distant panorama and small objects at an intermediate distance, particularly when the panorama is obscured, are important aspects of the visual environment both when determining the ideal learning walk and when using stored views to navigate. Implications are discussed in the context of behavioural research into the learning walks of ants.
2010
Visual memories of landmarks play a major role in guiding the habitual foraging routes of ants and bees, but how these memories engage visuo-motor control systems during guidance is poorly understood. We approach this problem through a study of image matching, a navigational strategy in which insects reach a familiar place by moving so that their current retinal image transforms to match a memorized snapshot of the scene viewed from that place. Analysis of how navigating wood ants correct their course when close to a goal reveals a significant part of the mechanism underlying this transformation. Ants followed a short route to an inconspicuous feeder positioned at a fixed distance from a vertical luminance edge. They responded to an unexpected jump of the edge by turning to face the new feeder position specified by the edge. Importantly, the initial speed of the turn increased linearly with the turn's amplitude. This correlation implies that the ants' turns are driven initially by their prior calculation of the angular difference between the current retinal position of the edge and its desired position in their memorized view. Similar turns keep ants to their path during unperturbed routes. The neural circuitry mediating image-matching is thus concerned not only with the storage of views, but also with making exact comparisons between the retinal positions of a visual feature in a memorized view and of the same feature in the current retinal image.