Recording from Snail Motor Nerves to Investigate Central Pattern Generation

Feeding in pond snails has long been a model system for central pattern generation and its modulation. The pattern is generated by a small set of neurons in the buccal ganglia, which innervate the buccal mass, esophagus, and salivary glands. In this exercise, students observe feeding behavior and then record and quantify rhythmic motor activity and its response to feeding stimulants and neuromodulators. In a standard three-hour class period, students do a dissection, record from several nerves, and perform experimental manipulations such as adding feeding stimulants, serotonin, or dopamine to the preparation. Depending on the course goals, data can be presented qualitatively or cyclic measurements and spike-rate analysis can be done. This exercise leads to discussion of neural circuitry and intrinsic properties that support pattern generation for rhythmic activities such as feeding, locomotion, and respiration.