They are only a few centimeters tall and their brains have a comparatively simple structure with less than one million neurons. Nevertheless, desert ants of the Cataglyphis genus possess abilities that distinguish them from many other creatures: The animals are able to orient themselves to the Earth's magnetic field. However, it was previously unknown where in the ants' brains the magnetic information is processed. This has now changed: In a new study published in the journal PNAS -- Proceedings of the National Academy of Sciences, the team shows that information about the Earth's magnetic field is primarily processed in the ants' internal compass, the so-called central complex, and in the mushroom bodies, the animals' learning and memory centers.

They were able to prove that desert ants orient themselves to the Earth's magnetic field during the learning walk phase. they not only investigated the ants' orientation behavior while the magnetic field was being manipulated, but also looked for changes in the nervous system of Cataglyphis as an expression of the newly acquired experience. The neuroanatomical brain analyses show that ants exposed to an altered magnetic field have a smaller volume and fewer synaptic complexes in an area of the brain responsible for the integration of visual information and learning, the so-called mushroom body. According to the scientists, this leads to the conclusion that magnetic information not only serves as a compass for navigation, but also as a global reference system that is crucial for the formation of spatial memory.

The results of their experiments prove that ants need a functioning magnetic compass during their learning walks in order to calibrate their visual compass and at the same time store images of the nest environment in their long-term memory. At the same time, their research extends far beyond the field of compass calibration in ants. They emphasizes that the results provide valuable information on how multisensory stimuli can influence neuronal plasticity of brain circuits for navigation in a critical phase of brain maturation. In a next step, the team now wants to investigate in which sensory organ the desert ant receives the magnetic information and via which sensory pathways it is transmitted and processed.