Freely moving animals may turn through several revolutions in one direction. While recording from freely moving animals, therefore, an electrical commutator is needed to prevent twisting of the wires that go from the electrode (moving and rotating with the head) to the amplifier/recorder (fixed to the ground).
When recording movements of freely roaming animals, their continuous rotation necessitates an electrical commutator. This device prevents the wires connecting moving electrodes (attached to the animal's head) to fixed amplifiers/recorders (anchored to the ground) from becoming tangled.