Visual perception of the Earth's magnetic field and night vision in songbirds

• Applicant: Professor Dr. Henrik Mouritsen
• Subject Area: Cognitive, Systems and Behavioural Neurobiology
• Term: from 2006 to 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 18693849

The behaviours and cues enabling migratory birds to find their way are quite well-understood, but almost all cognitive, physiological and molecular mechanisms remain unknown. Recent behavioural experiments and theoretical considerations have strongly suggested that perception of magnetic compass information in birds is dependent on radical-pair processes in the eye, which are light-induced. We have recently shown that potentially magnetosensitive molecules called cryptochromes are present in the retina of night-migratory birds and that the highest cryptochrome levels are found at night in retinal ganglion cells (RGCs) including displaced ganglion cells. Furthermore, the RGCs show high levels of neuronal activity when birds perform a magnetic orientation task. In contrast, the cryptochromes are virtually absent in the retina of non-migratory birds during the night. We have also shown that, in nightmigratory birds, a specific forebrain area, named Cluster N, is involved in processing night vision, possibly processing magnetically modulated signals from the cryptochromes. To find out whether the retina is involved in avian magnetoperception we will test if RGC responses are affected by magnetic field changes. We will use patch-clamp and extracellular, multielectrode recordings to test whether RGCs transmit magnetic information to the brain, or if generally improved night-vision sensitivity in migrants may explain activation of Cluster N.

• DFG Programme: Research Units
• Subproject of: FOR 701: Dynamics and Stability of Retinal Processing