A student apparatus for recording action potentials in cockroach legs.

A comparatively simple apparatus allows even beginning students to observe action potentials in the cockroach leg. The recordings are made extracellularly by impaling the leg on two insect pins. Deflection of large spines on the leg, which are each innervated by one sensory neuron, initiates the action potentials. Using this technique, students observe the all-or-nothing nature of action potentials, their coding of information by frequency, and sensory adaptation.