Mapping of magnetically induced brain activity in rodents
Here, we aim to map the neural circuits involved in magnetic orientation by means of whole brain activity mapping after magnetic stimulation. We make use of immediate early genes as a surrogate marker of neuronal activity, which we can automatically quantify in the whole brain with the iDISCO+ clearing technique (Renier et al. 2016) coupled with lightsheet-microscopy (see video of a cleared mole-rat brain in a lightsheet-microscope). We intend to reveal the primary sensory tissue by retrograde tracing starting from brain regions that process magnetic stimuli. As the magnetoreceptors of mole-rats are likely to contain the iron-oxide magnetite, we screen the target tissue with a variety of modern histological techniques (Electron microscopy, Synchrotron-XRF, etc.).
Neuronal processing of magnetic cues
In this project, our goal is to characterize how the brain processes magnetic stimuli. To this end we perform single-unit electrophysiological recordings in freely moving mole-rats. Recording from brain regions that have been identified in project 1 we are adressing how magnetic information is represented in the mole-rat navigation circuit. Do magnetic head direction cells exist? How are different cues integrated in the mole-rat navigation circuit?
The magnetic sense of planarians
In this project, co-funded by the DFG and ANR, we explore the magnetic sense of flatworms in collaboration with Hervè Cadiou. Hervé found that planarians use the Earth's magnetic field for orientation and that they have a light-independent, diurnal periodic inclination compass. Since these invertebrates do not express cryptochromes and they are also very easy to reproduce (clone), the animals are very well suited as a model organism to study the mechanisms of magnetic sense. In order to shed light on the molecular mechanisms of the magnetic sense of these animals, we carry out a series of behavioural, physiological and histological experiments. We pay particular attention to the magnetite and induction hypotheses of magnetoreception with the main objectives of identifying and characterising magnetite-containing cells (if present) and the behavioural and molecular characterisation of the electrical sense of the planarians.