Meeting Abstract
Sensory biology research has mostly focused on paired cephalic sensors that are connected to a relatively complex brain; however, some organisms have dispersed sensory systems with relatively simple nervous systems. How do simple nervous systems process large amounts of information from a multitude of distributed sensors? Certain species of chitons (Mollusca: Polyplacophora) have hundreds of image-forming eyes embedded in their 8 dorsal valves. Chitons are classically thought to have simple ladder-like nervous systems, so the evolution of a multitude of information-rich sensors seems to present a computational challenge to these animals. Learning how the optic nerves connect with the rest of the nervous system in chitons may give us insight into how chitons are processing the visual information collected by their eyes. To investigate this, the optic nerves from the eyes of Acanthopleura granulata were traced centrally using pressure microinjection of fluorescent lipophilic dyes. The optic nerves from eyes within the same region on a valve were found to coalesce after leaving the margin of the valve. They then traveled across the pallial groove where they terminated along the lateral nerve cord in proximity to where the eyes were located in the valves. Based on these results, we propose a model in which chitons process visual information locally from multiple eyes within certain regions of each valve. This is consistent with previous behavioral experiments that suggested that chitons process mechanosensory data locally.
