Cephalopod visual circuits

Cephalopods present one of the most complex invertebrate nervous systems, and exhibit elaborated behaviours, many of which are driven by their advanced visual system. We are generating the first synaptic resolution connectome of the visual circuits of a cephalopod, using the pygmy squid, Idiosepius hallami. The reduced dimensions of this miniaturised species enable the acquisition of the retina and optic lobe with an enhanced focused ion beam scanning electron microscope (FIBSEM). To bridge the detailed visual circuits afforded by our FIBSEM volume with behaviours such as learning or camouflage, the efferent optic lobe nerve tracts have to be followed to other brain regions, and from there onwards to the legs for coordinating locomotion or to the skin for camouflage. An X-ray nanotomography volume of the whole animal will provide that bridge and also guide future targeted FIBSEM volume acquisitions necessary to understand the sensorimotor transformations driving cephalopod behaviour.