|Full text PDF:||http://hdl.handle.net/10900/60504|
Visual navigation is widespread in animals, but how the light stimulus is translated into the coordinated motor output is poorly understood. In my thesis I reconstruct the neuronal connectome of the visual eyes in the marine annelid Platynereis using serial-section transmission electron microscopy. In the eye circuit, photoreceptor cells connect via three layers of interneurons to the motor neurons, which innervate trunk muscles and ciliated cells. By combining laser ablation and selective eye illumination experiments I could identify a visual eye circuit, which is able to detect spatial light information to perform either positive or negative phototaxis. I also showed a strong reciprocal interneuron motif, which modulates the contrast during visual navigation.