Columbus Instruments’ new Foot Misplacement Apparatus consists of a set of two stainless steel horizontal ladders. The spacing of the rungs on each ladder is different to accommodate both rats and mice. The spacing of the rungs can be made adjustable with the purchase of the “Adjustable Rung Upgrade.” At one end of the ladder, a dark compartment exists to entice the animal to walk toward the perceived “safety” of the dark cover. The apparatus provides an electric conditioning stimulus for training the animal by punishing them if they touch the metal plate, which is located below the horizontal ladder. After the animal is conditioned, an actual test is performed by placing the animal on one end of the ladder, and counting the number of missteps as it moves toward the dark compartment at the other end of the ladder.
Counting missteps is done automatically by detecting the change of resistance between the ladder and the metal plate. Each time the animal misses one of the rungs of the ladder and touches the metal plate below; a very small electric current is detected, amplified, and counted by a separate computerized counter. The animal is not aware of this current, as it is far below the threshold of the animal’s sensitivity. This apparatus allows for measurement of sensorimotor recovery following brain or spinal cord injury.