Multiple orientation cues in an Australian trunk-trail-forming ant, Iridomyrmex purpureus

2016 ◽  
Vol 64 (3) ◽  
pp. 227 ◽  
Author(s):  
Ashley Card ◽  
Caitlin McDermott ◽  
Ajay Narendra
Keyword(s):  
Path Integration ◽  
Trail Following ◽  
Visual Landmarks ◽  
Directional Information ◽  
Nest Location ◽  
Visual Landmark ◽  
Pheromone Trails ◽  
Orientation Cues ◽  
Celestial Compass ◽  
Path Integrator

Ants use multiple cues for navigating to a food source or nest location. Directional information is derived from pheromone trails or visual landmarks or celestial objects. Some ants use the celestial compass information along with an ‘odometer’ to determine the shortest distance home, a strategy known as path integration. Some trail-following ants utilise visual landmark information whereas few of the solitary-foraging ants rely on both path integration and visual landmark information. However, it is unknown to what degree trail-following ants use path integration and we investigated this in a trunk-trail-following ant, Iridomyrmex purpureus. Trunk-trail ants connect their nests to food sites with pheromone trails that contain long-lasting orientation information. We determined the use of visual landmarks and the ability to path integrate in a trunk-trail forming ant. We found that experienced animals switch to relying on visual landmark information, and naïve individuals rely on odour trails. Ants displaced to unfamiliar locations relied on path integration, but, surprisingly, they did not travel the entire homebound distance. We found that as the homebound distance increased, the distance ants travelled relying on the path integrator reduced.

scholarly journals A new navigational mechanism mediated by ant ocelli

2011 ◽  
Vol 7 (6) ◽  
pp. 856-858 ◽  
Author(s):  
Sebastian Schwarz ◽  
Antoine Wystrach ◽  
Ken Cheng
Keyword(s):  
Path Integration ◽  
Compound Eyes ◽  
Direct Path ◽  
Directional Information ◽  
Distance Information ◽  
Step Counter ◽  
Desert Ants ◽  
Celestial Compass ◽  
Path Integrator ◽  
Direction Opposite

Many animals rely on path integration for navigation and desert ants are the champions. On leaving the nest, ants continuously integrate their distance and direction of travel so that they always know their current distance and direction from the nest and can take a direct path to home. Distance information originates from a step-counter and directional information is based on a celestial compass. So far, it has been assumed that the directional information obtained from ocelli contribute to a single global path integrator, together with directional information from the dorsal rim area (DRA) of the compound eyes and distance information from the step-counter. Here, we show that ocelli mediate a distinct compass from that mediated by the compound eyes. After travelling a two-leg outbound route, untreated foragers headed towards the nest direction, showing that both legs of the route had been integrated. In contrast, foragers with covered compound eyes but uncovered ocelli steered in the direction opposite to the last leg of the outbound route. Our findings suggest that, unlike the DRA, ocelli cannot by themselves mediate path integration. Instead, ocelli mediate a distinct directional system, which buffers the most recent leg of a journey.

scholarly journals Role of the pheromone for orientation in the group foraging ant, Veromessor pergandei

2020 ◽  
Author(s):  
Cody A Freas ◽  
Marcia L Spetch
Keyword(s):  
Vector State ◽  
Group Foraging ◽  
Directional Information ◽  
Desert Ant ◽  
Correct Orientation ◽  
Celestial Compass ◽  
Vector Orientation ◽  
Veromessor Pergandei ◽  
Path Integrator

Role of the pheromone for orientation in the group foraging ant, Veromessor pergandei Navigation is comprised of a variety of strategies which rely on multiple external cues to shape a navigator’s behavioral output. An additional navigational challenge is coping with forces such as wind and water currents that push navigators off-course. Here, we explore the cue interactions that dictate orientation and foragers’ ability to counter course altering rotational changes in the desert ant, Veromessor pergandei. We found a cross sensory interaction between the pheromone cue and the path integrator underlies correct orientation during the inbound journey. The celestial compass provides directional information while the presence of the trail pheromone acts as a critical context cue, triggering distinct behavioral responses (vector orientation, search and backtracking). A particularly interesting interaction occurs between the pheromone and the forager’s vector state. While exposed to the pheromone, foragers orient to the vector direction regardless of vector state, while in the pheromone’s absence the current vector triggers the switch between behaviors. Such interactions maximize the foragers’ return to the nest and inhibit movement off the trail. Finally, our manipulations continuously pushed foragers away from their desired heading, yet foragers were highly proficient at counteracting these changes, steering to maintain a correct heading even at rotational speeds of ~40°/s.

scholarly journals Visual Navigation in Nocturnal Insects

Physiology ◽  
2016 ◽  
Vol 31 (3) ◽  
pp. 182-192 ◽  
Author(s):  
Eric Warrant ◽  
Marie Dacke
Keyword(s):  
Visual Processing ◽  
Visual Navigation ◽  
Compound Eyes ◽  
Visual Landmarks ◽  
Processing Strategies ◽  
Straight Line ◽  
Highly Sensitive ◽  
Celestial Compass ◽  
The Brain

Despite their tiny eyes and brains, nocturnal insects have evolved a remarkable capacity to visually navigate at night. Whereas some use moonlight or the stars as celestial compass cues to maintain a straight-line course, others use visual landmarks to navigate to and from their nest. These impressive abilities rely on highly sensitive compound eyes and specialized visual processing strategies in the brain.

scholarly journals The effect of step size on straight-line orientation

2019 ◽  
Vol 16 (157) ◽  
pp. 20190181 ◽  
Author(s):  
Lana Khaldy ◽  
Orit Peleg ◽  
Claudia Tocco ◽  
L. Mahadevan ◽  
Marcus Byrne ◽  
...  
Keyword(s):  
Sensory Information ◽  
Dung Beetles ◽  
Line Orientation ◽  
Step Size ◽  
Directional Information ◽  
Straight Path ◽  
Directional Error ◽  
Straight Line ◽  
Motor Error ◽  
Orientation Cues

Moving along a straight path is a surprisingly difficult task. This is because, with each ensuing step, noise is generated in the motor and sensory systems, causing the animal to deviate from its intended route. When relying solely on internal sensory information to correct for this noise, the directional error generated with each stride accumulates, ultimately leading to a curved path. In contrast, external compass cues effectively allow the animal to correct for errors in its bearing. Here, we studied straight-line orientation in two different sized dung beetles. This allowed us to characterize and model the size of the directional error generated with each step, in the absence of external visual compass cues ( motor error ) as well as in the presence of these cues ( compass and motor errors ). In addition, we model how dung beetles balance the influence of internal and external orientation cues as they orient along straight paths under the open sky. We conclude that the directional error that unavoidably accumulates as the beetle travels is inversely proportional to the step size of the insect, and that both beetle species weigh the two sources of directional information in a similar fashion.

scholarly journals Recalibration of path integration in hippocampal place cells

2018 ◽  
Author(s):  
Ravikrishnan P. Jayakumar ◽  
Manu S. Madhav ◽  
Francesco Savelli ◽  
Hugh T. Blair ◽  
Noah J. Cowan ◽  
...  
Keyword(s):  
Path Integration ◽  
Gain Factor ◽  
Place Cells ◽  
Cognitive Map ◽  
Mammalian Brain ◽  
Positional Error ◽  
Visual Landmarks ◽  
Augmented Reality System ◽  
Behavioral Evidence ◽  
Integration Gain

SummaryHippocampal place cells are spatially tuned neurons that serve as elements of a “cognitive map” in the mammalian brain1. To detect the animal’s location, place cells are thought to rely upon two interacting mechanisms: sensing the animal’s position relative to familiar landmarks2,3 and measuring the distance and direction that the animal has travelled from previously occupied locations4–7. The latter mechanism, known as path integration, requires a finely tuned gain factor that relates the animal’s self-movement to the updating of position on the internal cognitive map, with external landmarks necessary to correct positional error that eventually accumulates8,9. Path-integration-based models of hippocampal place cells and entorhinal grid cells treat the path integration gain as a constant9–14, but behavioral evidence in humans suggests that the gain is modifiable15. Here we show physiological evidence from hippocampal place cells that the path integration gain is indeed a highly plastic variable that can be altered by persistent conflict between self-motion cues and feedback from external landmarks. In a novel, augmented reality system, visual landmarks were moved in proportion to the animal’s movement on a circular track, creating continuous conflict with path integration. Sustained exposure to this cue conflict resulted in predictable and prolonged recalibration of the path integration gain, as estimated from the place cells after the landmarks were extinguished. We propose that this rapid plasticity keeps the positional update in register with the animal’s movement in the external world over behavioral timescales (mean 50 laps over 35 minutes). These results also demonstrate that visual landmarks not only provide a signal to correct cumulative error in the path integration system, as has been previously shown4,8,16–19, but also rapidly fine-tune the integration computation itself.

scholarly journals Flexible weighing of olfactory and vector information in the desert ant Cataglyphis fortis

2013 ◽  
Vol 9 (3) ◽  
pp. 20130070 ◽  
Author(s):  
Cornelia Buehlmann ◽  
Bill S. Hansson ◽  
Markus Knaden
Keyword(s):  
Path Integration ◽  
Food Sources ◽  
Feeding Site ◽  
Desert Ants ◽  
Desert Ant ◽  
Vector Information ◽  
Pass Through ◽  
Path Integrator ◽  
Odour Plumes ◽  
Cataglyphis Fortis

Desert ants, Cataglyphis fortis , are equipped with remarkable skills that enable them to navigate efficiently. When travelling between the nest and a previously visited feeding site, they perform path integration (PI), but pinpoint the nest or feeder by following odour plumes. Homing ants respond to nest plumes only when the path integrator indicates that they are near home. This is crucial, as homing ants often pass through plumes emanating from foreign nests and do not discriminate between the plume of their own and that of a foreign nest, but should absolutely avoid entering a wrong nest. Their behaviour towards food odours differs greatly. Here, we show that in ants on the way to food, olfactory information outweighs PI information. Although PI guides ants back to a learned feeder, the ants respond to food odours independently of whether or not they are close to the learned feeding site. This ability is beneficial, as new food sources—unlike foreign nests—never pose a threat but enable ants to shorten distances travelled while foraging. While it has been shown that navigating C. fortis ants rely strongly on PI, we report here that the ants retained the necessary flexibility in the use of PI.

Crossing fitness valleys during the evolution of limpet homing behaviour

2010 ◽  
Vol 5 (2) ◽  
pp. 274-282 ◽  
Author(s):  
Richard Stafford
Keyword(s):  
Path Integration ◽  
Fitness Landscapes ◽  
Hill Climbing ◽  
Global Maximum ◽  
Trail Following ◽  
Stepping Stones ◽  
Temporary Reduction ◽  
Homing Behaviour ◽  
Fitness Value ◽  
Hill Climbing Algorithms

AbstractEvolution is often considered a gradual hill-climbing process, slowly increasing the fitness of organisms. Here I investigate evolution of homing behaviour in simulated intertidal limpets. While the simulation of homing is only a possible mechanism by which homing may have evolved, the process allows an investigation of how evolution may occur over different fitness landscapes. With some fitness landscapes, in order to evolve path integration as a homing mechanism, a temporary reduction in an organism’s fitness was required — since high developmental costs occurred before successful homing strategies evolved. Simple hill-climbing algorithms, therefore, only rarely resulted in the evolution of a functional homing behaviour. The inclusion of trail-following greatly increases the frequency of success of evolution of a path integration strategy. Initially an emergent homing behaviour is formed combining path integration with trail-following. This also demonstrates evolution through exaptation, since in the simulation, the original role of trail-following is likely to be unrelated to homing. Analysis of the fitness landscapes of homing in the presence of trail-following behaviour shows a high variability of fitness, which results in the formation of ‘stepping-stones’ of high fitness across fitness valleys. By using these stepping-stones, simple hill-climbing algorithms can reach the global maximum fitness value.

scholarly journals The effects of spatial stability and cue type on spatial learning: Implications for theories of parallel memory systems

2021 ◽  
Author(s):  
Anthony McGregor
Keyword(s):  
Spatial Learning ◽  
Cognitive Mapping ◽  
Memory Systems ◽  
Cognitive Map ◽  
Cue Competition ◽  
Directional Information ◽  
Goal Location ◽  
Parallel Memory ◽  
Orientation Cues ◽  
Boundary Information

Some theories of spatial learning predict that associative rules apply under only limited circumstances. For example, learning based on a boundary has been claimed to be immune to cue competition effects because boundary information is the basis for the formation of a cognitive map, whilst landmark learning does not involve cognitive mapping. This is referred to as the cue type hypothesis. However, it has also been claimed that cue stability is a prerequisite for the formation of a cognitive map, meaning that whichever cue type was perceived as stable would enter a cognitive map and thus be immune to cue competition, while unstable cues will be subject to cue competition, regardless of cue type. In experiments 1 and 2 we manipulated the stability of boundary and landmark cues when learning the location of two hidden goals. One goal location was constant with respect to the boundary, and the other constant with respect to the landmark cues. For both cue types, the presence of distal orientation cues provided directional information. For half the participants the landmark cues were unstable relative to the boundary and orientation cues, whereas for the remainder of the participants the boundary was unstable relative to landmarks and orientation cues. In a second stage of training, all cues remained stable so that both goal locations could be learned with respect to both landmark and boundary information. According to the cue type hypothesis, boundary information should block learning about landmarks regardless of cue stability. According to the cue stability hypothesis, however, landmarks should block learning about the boundary when the landmarks appear stable relative to the boundary. Regardless of cue type or stability the results showed reciprocal blocking, contrary to both formulations of incidental cognitive mapping. Experiment 3 established that the results of Experiments 1 and 2 could not be explained in terms of difficulty in learning certain locations with respect to different cue types. In a final experiment, following training in which both landmarks and boundary cues signalled two goal locations, a new goal location was established with respect to the landmark cues, before testing with the boundary, which had never been used to define the new goal location. The results of this novel test of the interaction between boundary and landmark cues indicated that new learning with respect to the landmark had a profound effect on navigation with respect to the boundary, counter to the predictions of incidental cognitive mapping of boundaries.

scholarly journals From skylight input to behavioural output: a computational model of the insect polarised light compass

2018 ◽  
Author(s):  
Evripidis Gkanias ◽  
Benjamin Risse ◽  
Michael Mangan ◽  
Barbara Webb
Keyword(s):  
Path Integration ◽  
Sensor Array ◽  
Neural Model ◽  
Biological Data ◽  
Insect Brain ◽  
Uneven Terrain ◽  
Starting Point ◽  
Celestial Compass ◽  
Insect Eye ◽  
New Hypothesis

AbstractMany insects navigate by integrating the distances and directions travelled on an outward path, allowing direct return to the starting point. Fundamental to the reliability of this process is the use of a neural compass based on external celestial cues. Here we examine how such compass information could be reliably computed by the insect brain, given realistic constraints on the sky polarisation pattern and the insect eye sensor array. By processing the degree of polarisation in different directions for different parts of the sky, our model can directly estimate the solar azimuth and also infer the confidence of the estimate. We introduce a method to correct for tilting of the sensor array, as might be caused by travel over uneven terrain. We also show that the confidence can be used to approximate the change in sun position over time, allowing the compass to remain fixed with respect to ‘true north’ during long excursions. We demonstrate that the compass is robust to disturbances and can be effectively used as input to an existing neural model of insect path integration. We discuss the plausibility of our model to be mapped to known neural circuits, and to be implemented for robot navigation.Author summaryWe propose a new hypothesis for how insects process polarised skylight to extract global orientation information that can be used for accurate path integration. Our model solves the problem of solar/anti-solar meridian ambiguity by using a biologically constrained sensor array, and includes methods to deal with tilt and time, providing a complete insect celestial compass output. We analyse the performance of the model using a realistic sky simulation and various forms of disturbances, and compare the results to both engineering approaches and biological data.

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