This review focuses on the neural control of feeding in Aplysia. Its purpose is to highlight distinctive features of the behavior and to describe their neural basis. In a number of molluscs, food is grasped by a radula that protracts, retracts, and hyperretracts. In Aplysia, however, hyperretraction can require afferent activation. Phase-dependent regulation of sensorimotor transmission occurs in this context. Aplysia also open and close the radula, generating egestive as well as ingestive responses. Thus, the feeding network multitasks. It has a modular organization, and behaviors are constructed by combinations of behavior-specific and behavior-independent neurons. When feeding is initially triggered in Aplysia, responses are poorly defined. Motor activity is not properly configured unless responses are repeatedly induced and modulatory neurotransmitters are released from inputs to the central patter generator (CPG). Persistent effects of modulation have interesting consequences for task switching.
