Magnetoreception – the ability to sense the Earth’s magnetic field

David Keays is one of the mega stars of animal navigation research and has spent a life time trying to work out how magnetism might work.

Here is a summary of his latest work:

Magnetoreception is the ability to sense the Earth’s magnetic field, which is used for orientation and navigation.

Behavioural experiments have shown that it is employed by many species across all vertebrate classes; however, our understanding of how magnetic information is processed and integrated within the central nervous system is limited.

In this Commentary, we review the progress in birds and rodents, highlighting the role of the vestibular and trigeminal systems as well as that of the hippocampus. We reflect on the strengths and weaknesses of the methodologies currently at our disposal, the utility of emerging technologies and identify questions that we feel are critical for the advancement of the field.

We expect that magnetic circuits are likely to share anatomical motifs with other senses, which culminates in the formation of spatial maps in telencephalic areas of the brain. Specifically, we predict the existence of spatial cells that encode defined components of the Earth’s magnetic field.

Malkemper, E. P., Nimpf, S., Nordmann, G. C. & Keays, D. A. 2020 Neuronal circuits and the magnetic sense: central questions. The Journal of Experimental Biology223, jeb232371. doi: 10.1242/jeb.232371. Malkemper3 2020 

Posted in Animal Migration, Bird Navigation, How animals navigate, Sense of Direction | Leave a comment

Eyes are essential for magnetoreception in a mammal

Here is another interesting paper:

Mole-rat lives underground and basically cannot see and is often studied to understand how they navigate.

Caspar, K. R., Moldenhauer, K., Moritz, R. E., Němec, P., Malkemper, E. P. & Begall, S. 2020 Eyes are essential for magnetoreception in a mammal. Journal of The Royal Society Interface17, 20200513. doi: doi:10.1098/rsif.2020.0513. Caspar2 2020 

Several groups of mammals use the Earth’s magnetic field for orientation, but their magnetosensory organ remains unknown.

The Ansell’s mole-rat (Fukomys anselli, Bathyergidae, Rodentia) is a microphthalmic subterranean rodent with innate magnetic orientation behaviour.

Previous studies on this species proposed that its magnetoreceptors are located in the eye. To test this hypothesis, we assessed magnetic orientation in mole-rats after the surgical removal of their eyes compared to untreated controls. Initially, we demonstrate that this enucleation does not lead to changes in routine behaviours, including locomotion, feeding and socialising.

We then studied magnetic compass orientation by employing a well-established nest-building assay under four magnetic field alignments. In line with previous studies, control animals exhibited a significant preference to build nests in magnetic southeast.

By contrast, enucleated mole-rats built nests in random magnetic orientations, suggesting an impairment of their magnetic sense.

The results provide robust support for the hypothesis that mole-rats perceive magnetic fields with their minute eyes, probably relying on magnetite-based receptors in the cornea.

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Memories Can Be Injected and Survive Amputation and Metamorphosis

There has always been huge uncertainty as to how migrating animals learn where to go.  The cuckoo is a perfect example, as the newly hatched birds must travel from Europe to The Congo Basin for the winter, but how do they know the way (as their parents departed sometime before and they travel on their own)?  The route is not a straight one and they must stop as various places on the way to “refuel” (eat hairy caterpillars) in order to be able to cross the Sahara.


Here is an explanation:

http://m.nautil.us/blog/memories-can-be-injected-and-survive-amputation-and-metamorphosis


Richard Nissen
editor
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The “V” formation of flying geese

A recent piece of work by a team lead by A. . Kölzsch from Germany tracked a family of Greater White-fronted Goose (Anser albifrons) 

This goose is a great migrator and winters (December to February) in Western Europe where the researchers were helped by colleagues in the Netherlands for this study.  The geese migrate in the Spring to the High Artic where they breed from June. Like other species the autumn route is not the same as the spring migration.

The study wanted to research the “V” formation flying on these geese.  The accepted theory is that they use this formation as the slip stream of birds flying in front aid birds flying behind.  It has been shown that the lead birds take turns to lead.   However, in this piece of work they show that in family groups (they found a family composed of a father, mother and two young),  they discovered that the family fly in formation with the mother and father taking turns to lead the family group.

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To cross or not to cross

Recently Vera Brust, Bianca Michalik and Ommo Hüppop  have produced a paper called “To cross or not to cross – thrushes at the German North Sea coast adapt flight and routing to wind conditions in autumn”.

They looked at some of the thrush family (blackbirds, redwings and song thrushes) that migrate across the North sea from the German North Sea coast to Britain at night during the autumn to escape the harsh winter conditions on the continent.  This paper suggests that whilst there is definitely a genetic component to navigation, the birds preferred clear skies with a wind blowing from the west
with favourable north wind component. 

We also have two papers led by Alessandro Cresci, suggesting that Atlantic Haddock (Melanogrammus aeglefinus) Larvae have a Magnetic Compass that Guides their Orientation and Glass Eels (Anguilla anguilla) imprint the magnetic direction of tidal currents from their juvenile estuaries.  It appears that there is increasing evidence that a lot of sea creatures use magnetic cues to help with their navigation

Richard Nissen
editor

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COGNITIVE NAVIGATION SYMPOSIUM: SENSE OF DIRECTION

Recently Prof Kate Jeffery, working with The Royal Institute of Navigation (RIN), gave a one day symposium at University College London.

Themes
• How animals orient – perspectives from ethology and neuroscience 
• How humans orient – perspectives from cognitive neuroscience 
• Helping humans orient – perspectives from architecture and design 
• The future – building a more navigable world 

Speakers 

Prof Kate Jeffery

Prof Kate Jeffery gave a great introduction telling us about all the important work that had laid the ground work for our knowledge of our navigational skills from a perspective of how the brain processes and interprets navigational information to enable navigation.

David Barrie, author of “Incredible Journeys”

David is very eloquent and his recent book is a great primer for everything going on in the navigation field. He is brave at describing areas where Science still does not know the answers.

Barbara Webb, University of Edinburgh. 

Barbara Webb gave an enthralling description of the processing used by ants to find their way home and also to re-visit food sources.  She showed the entangled structure of the ant brain and then showed how functionally it worked with super clarity.

Caswell Barry, University College London 

This presentation tied in with the one by Barbara Webb on how animals can use the grid cells they have for navigation and used computer simulations to prove the point.

Eric Warrant, Lund University

Eric described the astonishing migration of the Australian Bogong Moth.  You will find more about his work already published on this site see “Long distance Nocturnal navigator”.

Vladislava Segan

She talked about how dementia changes people’s lives and that we should concentrate on what they can still do and what they can no longer do well.

Tim Fendley, Legible London 

His firm does the signing and directional strategies for people navigating around cities etc.  His firm designed the maps outside tube stations in London.

Tim Stonor, Space Syntax 

Tim Stoner is an architect and interested in how cities work and why.

Niall McLaughlin, architect 

This presentation was a fascinating description of the design effort his firm has put into designing spaces for people with dementia and Alzheimer’s disease.

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“Those who work dogs in the field seem to enjoy a closer, sometimes telepathic relationship with their charges that ’s obvious if you know what to look for. A good huntsman’s rapport with his pack – “the golden thread” – is much admired, but so are the feats of gundogs indispensable to every day’s shooting”.

Country Life Magazine (UK) issue July 24th 2019 had an article entitled “Every dog has its day”

Those who work closely with animals seem to have a very special relationship with them that may not agree well with established scientific thinking.
Editor

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