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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 171 (1992), S. 285-288 
    ISSN: 1432-1351
    Keywords: Ants ; Path ; integration ; Detours ; Homing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary We ask whether desert ants (Cataglyphis fortis) perform path integration on their homeward as well as on their outward journey. If path integration does occur on the return journey, then, after an enforced detour, the ant's trajectory should point directly at its nest. To test whether this is so, ants were trained to forage at a spot 25 m from their nest. As an ant began its return journey to the nest, it was caught and transported to a test area where it was released either 2 m or 12 m from a wide barrier which obstructed its homeward path. The direction of the ants' trajectory after detouring around the barrier corresponded closely to that predicted on the assumption that the home vector is accurately updated during the detour.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 170 (1992), S. 435-442 
    ISSN: 1432-1351
    Keywords: Ants ; Landmarks ; Learning ; Navigation ; Vision
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 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.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 172 (1993), S. 109-113 
    ISSN: 1432-1351
    Keywords: Frogs ; Distance vision ; Retinal elevation ; Detours
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Grass frogs, Rana pipiens, will detour around a barrier to reach prey on the other side. However, if the distance between prey and barrier is short, frogs attempt to push through the barrier and reach the prey directly. The relationship between the probability of detouring and the distance between prey and barrier is the same whether the frog's starting position is 4 cm or 8 cm from the barrier. This suggests that frogs measure the absolute separation between the two objects. To discover whether the retinal elevation of the bottom of the barrier contributes to measuring this distance, the relationship between the frequency of detouring and barrier-prey distance was examined in several experiments in which the retinal position of the bottom of the barrier was manipulated. No evidence was obtained that the barrier's retinal elevation helps in gauging distance. On the other hand, retinal elevation influences strongly how far a frog lunges to reach its prey. It is suggested that different cues to distance are applied to the two classes of object because, under natural circumstances, it is difficult to judge where a barrier emerges from the ground. A barrier may be hard to detect below the horizon because of the low contrast between it and the ground, or because vegetation and ground litter mask where the barrier meets the ground. In contrast, the prey's movements make it easily detectable against a stationary background and the prey's short height means that partial occlusion will have little effect on its apparent vertical position in the visual field.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 179 (1996), S. 395-406 
    ISSN: 1432-1351
    Keywords: Honeybees ; Vector averaging ; Motor trajectories ; Path-integration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Honeybees flying repeatedly over the same trajectory link it to an associated visual stimulus such that on viewing the stimulus they perform a trajectory in the habitual direction. To test if trajectory length can also be linked to a visual stimulus, bees were trained to fly through a multi-comparmented maze. Bees flew through a multi-compartmented maze. In one compartment a short trajectory could be linked to a stripe pattern oriented at 45° to the horizontal. In another compartment a longer trajectory could be linked to 135° stripes. Bees made both associations: their trajectories were short when viewing 45° stripes and longer when viewing 135° stripes. 90° stripes evoked trajectories of intermediate length. To test if distance and direction are linked independently to stripe orientation, a bee's trajectory was linked to 135° stripes in one compartment and to 45° stripes in another. These trajectories were the same length but differed in their horizontal direction by 60° or by 120°. 90° stripes evoked trajectories of intermediate direction which were shorter than those elicited by either training pattern. Bees were also trained to generate one long and one short trajectory with directions 120° apart. The trajectories elicited by 90° stripes were then biased towards the direction of the long training vector. Length and direction are not treated separately. The rules for combining trajectories resemble those of vector averaging.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 181 (1997), S. 343-353 
    ISSN: 1432-1351
    Keywords: Key words Honeybees  ;  Visual pattern learning  ; Context learning  ;  Mazes  ;  Places
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract To investigate the priming of memories by contextual cues, bees were trained to negotiate two mazes in different places 25 m apart. In the first maze, bees flew leftwards when the inner wall of the maze was covered with 45° stripes or rightwards when the inner wall was coloured yellow. In the second maze, bees flew rightwards on viewing 135° diagonal stripes or leftwards on viewing blue. The trajectories evoked by 45° or 135° stripes were similar in both mazes. However, vertical stripes were treated like 45° stripes in maze 1 and like 135° stripes in maze 2. Contextual cues prime the response to stripes that are oriented in the training condition for that site so influencing responses to stripes in closely neighbouring orientations. What objects in a bee's surroundings determine its sense of place? Bees were trained to different visual patterns at two sites 40 m apart (A+ versus A– at site A, and E+ versus E– at site E). A+ was preferred over A– and E+ was preferred over E– at both training sites. A preference for A+ over E+ exhibited at site A dropped gradually with distance to suggest that spatial context includes both close and distant objects.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 172 (1993), S. 693-706 
    ISSN: 1432-1351
    Keywords: Bees ; Routes ; Sequence learning ; Memory retrieval
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Bees of several genera make foraging trips on which they visit a series of plants in a fixed order. To help understand how honeybees might acquire such routes, we examined whether (1) bees learn motor sequences, (2) they link motor instructions to visual stimuli, (3) their visual memories are triggered by contextual cues associated with the bees' position in a sequence. 1. Bees were trained to follow a complex route through a series of obstacles inside a large, 250 cm by 250 cm box. In tests, the obstacles were briefly removed and the bees continued to fly the same zig-zag trajectory that they had when the obstacles were present. The bees' complex trajectory could reflect either the performance of a sequence of motor instructions or their attempt to reach fixed points in their environment. When the point of entry to the box was shifted, the bees' trajectory with respect to the new point of entry was relatively unchanged, suggesting that bees have learnt a motor sequence. 2. Bees were trained along an obstacle course in which different flight directions were associated with the presence of different large patches of colour. In tests, the order of coloured patches was reversed, the trajectory followed by the bees was determined by the order of colours rather than by the learnt motor sequence suggesting that bees will readily link the performance of a particular trajectory to an arbitrary visual stimulus. 3. Bees flew through a series of 3 similar compartments to reach a food reward. Passage from one compartment to the next was only possible through the centre of one of a pair of patterns, e.g. white + ve vs. black — ve in the first box, blue + ve vs. yellow -ve in the second, vertical + ve vs. horizontal — ve in the last. In some tests, bees were presented with a white vs. a vertical stimulus in the front compartment, while, in other tests, the same pair of stimuli was presented in the rear compartment. Bees preferred the white stimulus when tested in the first 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.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 175 (1994), S. 171-177 
    ISSN: 1432-1351
    Keywords: Honeybee ; Behaviour ; Orientation flights ; Distance learning ; Size learning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Bees learn both the absolute distance and the apparent size of landmarks in the vicinity of a foraging site. They learn about landmarks both when approaching and when leaving the site. Whereas learning on arrival can take place on every visit to the food source, learning on departure is limited to the first few visits, when the bee Turns Back and Looks (TBL) at the feeder in a stereotyped manoeuvre before flying off. We investigated whether one specific function of TBLs is to acquire information about the absolute distance of landmarks from the feeding site. Bees were trained to forage from a feeder which lay at a fixed distance from a cylinder. During training, bees were exposed to the cylinder either only while they approached and landed on the feeder, or only on their departure from it, or at both of these times. Tests on trained bees immediately after the TBL phase revealed that those bees which had viewed the cylinder only on arrival had learnt the apparent size of the cylinder, but not its distance from the feeder. In contrast, bees which saw the cylinder on departure had learnt its absolute distance. They also learnt the cylinder's apparent size, provided that the cylinder was close to the feeder. Bees which had viewed the cylinder on arrival as well as on departure learnt both absolute distance and apparent size. Distance dominated the bees' behaviour in the initial phase of learning, apparent size was more important later on. We suggest that early during learning bees need information about the 3-D structure of the environment so that they can identify those landmarks close to a foraging site which will specify accurately the site's position. This information is acquired during TBLs. Later, landmark guidance can be achieved by 2-D image matching.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 177 (1995), S. 287-298 
    ISSN: 1432-1351
    Keywords: Visuo-motor learning ; Interpolation ; Bees ; Navigation ; Motor commands
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We investigated the ability of bees to associate a motor parameter with a sensory one. Foragers were trained to fly along a prescribed route through a large box which was partitioned into compartments. Access from one compartment to the next was through a hole in each partition. In two of the compartments, the back wall was covered with a grating of black and white stripes. Stripe orientations and the required trajectories differed in the two compartments so giving bees the opportunity to learn that one stripe orientation signalled the need to fly leftwards and the other rightwards. We videotaped the bees' trajectories through one of these compartments in tests with the grating on the back wall in one of four possible orientations. Flight trajectories to stripes in the training orientations were appropriately to the left or to the right implying that bees had linked a given flight direction to a given stripe orientation. With gratings oriented between the training values, flight directions were, under some conditions, intermediate between the training directions. This interpolation indicates that the training regime had induced a continuous mapping between stripe orientation and trajectory direction and thus suggests that trajectory direction is a motor parameter which is encoded explicitly within the brain. We describe a simple network that interpolates much like bees and we consider how interpolation may contribute to the ability of bees to navigate flexibly within a familiar environment.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 177 (1995), S. 737-747 
    ISSN: 1432-1351
    Keywords: Learning flights ; Visual navigation ; Visual landmarks ; Preferred views ; Wasps
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The flights of individual wasps (Vespula) were recorded as they approached a small feeder on the ground that was marked by a black cylinder ca 15 cm away. Two navigational strategies are used in these approaches. Initially, the wasp aims at the cylinder, treating it as a beacon and fixating it with frontal retina. In the last stage of the flight, the wasp assumes a preferred orientation so that the cylinder takes up a constant, more peripheral retinal position as the wasp nears the feeder. Path guidance by image-matching is likely to be limited to this final segment of the return. Wasps could gain the information needed for these distinct navigational strategies during the learning flights that they perform on their initial departures from the feeder. They fly away from the feeder in a series of arcs while turning at a mean angular velocity of 226°/s. The cylinder tends to be viewed with frontal retina during the arcs suggesting that the information required for aiming at the cylinder is acquired then. For image matching, the appearance of the cylinder needs to be learnt when the wasp is in the orientation that it adopts close to the feeder on its return flight. Wasps tend to assume this orientation during learning flights while they face the feeder. Such inspections of the feeder occur at the ends of arcs when a wasp's turning velocity is low.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 181 (1997), S. 47-58 
    ISSN: 1432-1351
    Keywords: Key words Bees ; Wasps ; Navigation ; Landmark guidance ; Image matching
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract In order to analyse how landmarks guide the last stages of an insect's approach to a goal, we recorded many flights of individual wasps and honeybees as they flew to an inconspicuous feeder on the ground that was marked by one or by two nearby landmarks. An individual tends to approach the feeder from a constant direction, flying close to the ground. Its body is oriented in roughly the same horizontal direction during the approach so that the feeder and landmarks are viewed over a narrow range of directions. Consequently, when the insect arrives at the feeder, the landmarks take up a standard position on the retina. Three navigational strategies govern the final approach. The insect first aims at a landmark, treating it as a beacon. Secondly, bees learn the appearance of a landmark with frontal retina and they associate with this stored view a motor trajectory which brings them from the landmark sufficiently close to the goal that it can be reached by image matching. Insects then move so as to put the landmark in its standard retinal position. Image matching is shown to be accomplished by a control system which has as set points the standard retinal position of the landmark and some parameter related to its retinal size.
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