We have developed a new preparation that permits us to change the effects of body loading by using magnets. The tape is lightweight and can be readily carried during walking. The effects of body weight are altered by using the tape as the point of attachment of neodymium magnets. Body weight is decreased by holding the animal with a large magnet mounted on the end of a rod. The animal then walks above an oiled glass plate.
Body weight is increased by attaching very small magnets directly to the tape.
Transient increases in forces can then be produced through an electrical coil that induces a magnetic field in the walking arena. We have used this preparation to study the activities of force receptors of the legs at different levels of body loading. The tibial campaniform sensilla are sense organs that monitor forces in the leg through strains in the exoskeleton. This activity has been thought to result when body weight is placed upon a leg. In some experiments, the plate was oriented horizontally.