A classical experiment in which students record spontaneous motor activity from a crayfish abdominal ganglion. It helps students understand that multiple units in a recording can be distinguished by spike shape and height. Students also apply nicotine to the ganglion, which produces high levels of motor neuron firing. The exercise is part of an online lab manual for an undergraduate neurophysiology course: http://www.science.smith.edu/departments/NeuroSci/courses/bio330/labs.html. Each exercise has a video demonstrating the procedure, written instructions, and color images showing details.