A neural pathway for learning that food is inedible in Aplysia.

Aplysia can be taught to stop responding to inedible food, by pairing lip stimuli with stimuli arising from food stuck in the buccal cavity. When the esophageal nerves innervating the gut are cut. Aplysia cease responding to inedible food in a mean of 2.09 times longer than when these nerves are intact. Patterning of feeding movements is also changed. Cessation of responses in lesioned animals may be due to adaptation caused by lip stimulation. The data suggest that the esophageal nerves carry information about whether food is edible or inedible.