Multi-modal route memories?
AntBot
Abstract: “Autonomous outdoor navigation requires reliable multisensory fusion strategies. Desert ants travel widely every day, showing unrivaled navigation performance using only a few thousand neurons. In the desert, pheromones are instantly destroyed by the extreme heat. To navigate safely in this hostile environment, desert ants assess their heading from the polarized pattern of skylight and judge the distance traveled based on both a stride-counting method and the optic flow, i.e., the rate at which the ground moves across the eye. This process is called path integration (PI). Although many methods of endowing mobile robots with outdoor localization have been developed recently, most of them are still prone to considerable drift and uncertainty. We tested several ant-inspired solutions to outdoor homing navigation problems on a legged robot using two optical sensors equipped with just 14 pixels, two of which were dedicated to an insect-inspired compass sensitive to ultraviolet light. When combined with two rotating polarized filters, this compass was equivalent to two costly arrays composed of 374 photosensors, each of which was tuned to a specific polarization angle. The other 12 pixels were dedicated to optic flow measurements. Results show that our ant-inspired methods of navigation give precise performances. The mean homing error recorded during the overall trajectory was as small as 0.67% under lighting conditions similar to those encountered by ants. These findings show that ant-inspired PI strategies can be used to complement classical techniques with a high level of robustness and efficiency.”
Dupeyroux, J., Serres, J. R. and Viollet, S. 2019 AntBot: A six-legged walking robot able to home like desert ants in outdoor environments. Science Robotics, doi: 10.1126/scirobotics.aau0307.
JEB Special Issue on Brains and Navigation
Olfactory navigation in aquatic gastropods
Russell C. Wyeth
J Exp Biol 2019 222:jeb185843. doi:10.1242/jeb.185843
Summary: Review of the past research and future prospects for understanding odour-based navigation behaviour by gastropods, covering behavioural patterns, navigational strategies and neural underpinnings.
Behavioural and neuronal basis of olfactory imprinting and kin recognition in larval fish
Gabriele Gerlach, Kristin Tietje, Daniela Biechl, Iori Namekawa, Gregor Schalm and Astrid Sulmann
J Exp Biol 2019 222:jeb189746. doi:10.1242/jeb.189746
Summary: This Review focuses on olfactory imprinting processes that numerous species use to recognize kin or their natal environment later in life.
There and back again: natal homing by magnetic navigation in sea turtles and salmon
Kenneth J. Lohmann and Catherine M. F. Lohmann
J Exp Biol 2019 222:jeb184077. doi:10.1242/jeb.184077
Summary: New findings indicate that long-distance natal homing in salmon and sea turtles involves an ability to navigate back to the magnetic signature of the home area.
The internal maps of insects
Barbara Webb
J Exp Biol 2019 222:jeb188094. doi:10.1242/jeb.188094
Summary: Insect behaviour can be explained as a combination of path integration, vector memory and view memory, but what is the evidence that these geometric capabilities form an integrated map?
The genetics and epigenetics of animal migration and orientation: birds, butterflies and beyond
Christine Merlin and Miriam Liedvogel
J Exp Biol 2019 222:jeb191890. doi:10.1242/jeb.191890
Summary: This Review summarizes our understanding of the genetics and epigenetics of animal migration and outlines a vision to harness both technical advances and comparative approaches to move the field forward.
Non-Euclidean navigation
William H. Warren
J Exp Biol 2019 222:jeb187971. doi:10.1242/jeb.187971
Summary: The behavioral evidence for Euclidean cognitive maps is unpersuasive. Recent experiments indicate that human spatial knowledge is better described by a labeled graph, which incorporates local distance and angle information.
Using on-board sound recordings to infer behaviour of free-moving wild animals
Stefan Greif and Yossi Yovel
J Exp Biol 2019 222:jeb184689. doi:10.1242/jeb.184689
Summary: We review new possibilities for monitoring the behaviour of wild animals in the field using on-board audio recordings.
The potential of virtual reality for spatial navigation research across the adult lifespan
Nadine Diersch and Thomas Wolbers
J Exp Biol 2019 222:jeb187252. doi:10.1242/jeb.187252
Summary: This Review describes how virtual reality is used to study spatial navigation across species and discusses the benefits and challenges when using it in older age groups.
The insect central complex and the neural basis of navigational strategies
Anna Honkanen, Andrea Adden, Josiane da Silva Freitas and Stanley Heinze
J Exp Biol 2019 222:jeb188854. doi:10.1242/jeb.188854
Summary: Neural circuits of the insect central complex are involved in guiding multiple navigation strategies, and the emerging core circuit for navigational decisions might provide an overarching framework of central-complex function.
Celestial navigation in Drosophila
Timothy L. Warren, Ysabel M. Giraldo and Michael H. Dickinson
J Exp Biol 2019 222:jeb186148. doi:10.1242/jeb.186148
Summary: In this Review, we describe how the fruit fly, Drosophila melanogaster, uses the position of the sun and the pattern of polarized skylight to maintain a constant heading during long-distance dispersal flights.
The brain behind straight-line orientation in dung beetles
Basil el Jundi, Emily Baird, Marcus J. Byrne and Marie Dacke
J Exp Biol 2019 222:jeb192450. doi:10.1242/jeb.192450
Summary: Insights into the neural mechanisms underlying compass orientation in dung beetles are placed into the context of the mechanisms of other insects.
Origin and role of path integration in the cognitive representations of the hippocampus: computational insights into open questions
Francesco Savelli and James J. Knierim
J Exp Biol 2019 222:jeb188912. doi:10.1242/jeb.188912
Summary: Path integration is one of the fundamental computations giving rise to the cognitive map and possibly other non-spatial representations in the hippocampal formation and its subcortical afferents.
Merging information in the entorhinal cortex: what can we learn from robotics experiments and modeling?
Philippe Gaussier, Jean Paul Banquet, Nicolas Cuperlier, Mathias Quoy, Lise Aubin, Pierre-Yves Jacob, Francesca Sargolini, Etienne Save, Jeffrey L. Krichmar and Bruno Poucet
J Exp Biol 2019 222:jeb186932. doi:10.1242/jeb.186932
Summary: Grid cells related to path integration and vision are explained as modulo projections of different cortical activities. The entorhinal cortex appears as a generic merging tool building hash codes.
Navigation and the developing brain
Nora S. Newcombe
J Exp Biol 2019 222:jeb186460. doi:10.1242/jeb.186460
Summary: Spatial development in humans takes a decade or more to unfold, and involves tuning initial systems in response to changing motor capacities and environmental feedback.
The navigational nose: a new hypothesis for the function of the human external pyramid
Lucia F. Jacobs
J Exp Biol 2019 222:jeb186924. doi:10.1242/jeb.186924
Summary: The human nose respires and sniffs yet current theory addresses only its respiratory function; the nose may also allow stereo olfaction and may have evolved for this in early Homo.
Learning things inside out
How and when ants learn the visual cues that guide their habitual routes is a bit of a known-unknown for insect navigation studies. This paper gives us a rather intriguing clue about how things might work. Ants were restricted to visual experience on their outbound or inbound journeys only, then tested to see how much they had learnt about an experimentally provided visual panorama as they tried to navigate back to their nest. Perhaps surprisingly, ants that had experienced this panorama on the way to the food only, showed that they had a more robust visual memory than ants that had experienced it on homewards trips. Previous research has suggested that the visual memories that guide outward and inward journeys are kept separate in the insect brain, but this suggests that from the learning perspective the separation of out and in is much more complex.
Freas, C. A., and Spetch, M. L. (2019). Terrestrial cue learning and retention during the outbound and inbound foraging trip in the desert ant, Cataglyphis velox. Journal of Comparative Physiology A, 1-13.
Back to the beginning again
Experienced ant foragers show idiosyncratic visually guided routes though their environment. These routes can appear “fixed” because of their regularity, but actually ants maintain the ability to modify the routes, to gradually increase efficiency or to respond to new information. We investigated the process of route modification by repeatedly capturing ants just as they were about to enter their nest after a route home and returning them to the start. This process of unsuccessful homing led to route degradation and an increase in behaviours often associated with visual learning. Interestingly, these effects were specific to the portions of routes over which the ants had been forced to re-run and were evident even if ants had a 24 hour wait before being allowed to run home again. Thus we can conclude that this process of unsuccessful route homing is modifying long-term specific visual guidance memories, rather than being due to short term adaptation.
Wystrach, A., Schwarz, S., Graham, P., & Cheng, K. (2019). Running paths to nowhere: repetition of routes shows how navigating ants modulate online the weights accorded to cues. Animal Cognition, 1-10.
Minimal polarisation sensors
Abstract: Many insects such as desert ants, crickets, locusts, dung beetles, bees and monarch butterflies have been found to extract their navigation cues from the regular pattern of the linearly polarized skylight. These species are equipped with ommatidia in the dorsal rim area of their compound eyes, which are sensitive to the angle of polarization of the skylight. In the polarization-based robotic vision, most of the sensors used so far comprise high-definition CCD or CMOS cameras topped with linear polarizers. Here, we present a 2-pixel polarization-sensitive visual sensor, which was strongly inspired by the dorsal rim area of desert ants’ compound eyes, designed to determine the direction of polarization of the skylight. The spectral sensitivity of this minimalistic sensor, which requires no lenses, is in the ultraviolet range. Five different methods of computing the direction of polarization were implemented and tested here. Our own methods, the extended and AntBot method, outperformed the other three, giving a mean angular error of only 0.62° ± 0.40° (median: 0.24°) and 0.69° ± 0.52° (median: 0.39°), respectively (mean ± standard deviation). The results obtained in outdoor field studies show that our celestial compass gives excellent results at a very low computational cost, which makes it highly suitable for autonomous outdoor navigation purposes.
Dupeyroux, J., Viollet, S., & Serres, J. R. (2019). Polarized skylight-based heading measurements: a bio-inspired approach. Journal of the Royal Society Interface, 16(150), 20180878.
The path most travelled
Many flying animals have been shown to incorporate extended environmental features in the routes that they take through the world. For instance, GPS tracking of pigeons has shown beautiful examples of individual birds taking routes that track along large roads. Data is hard to come by for bees because of the necessity of expensive radar tracking systems, but from this paper and others, it is clear that bees also use ground structure for navigation. This is shown both in learning flights and foraging trips. Genuine manipulative experiments are hard to do for such large scale behaviours, but here, by varying the type of elongated ground structure and its orientation the authors were able to conclude that structures are characterised (in the bee’s brain) by their appearance and compass alignment, suggesting some multi-modal learning.
Menzel, R., Tison, L., Fischer-Nakai, J., Cheeseman, J., Sol Balbuena, M., Chen, X., … & Greggers, U. (2019). Guidance of Navigating Honeybees by Learned Elongated Ground Structures. Frontiers in Behavioral Neuroscience, 12.
