A ladder paradigm for studying skilled and adaptive locomotion in the cat.

A circular horizontal ladder is described which is suitable for studying skilled and adaptive locomotion in the cat. Four mechanisms built into the ladder require the animal to adapt its normal walking by making either corrective manoeuvres following an unpredictable disturbance, or anticipatory changes informed by vision. In addition to these features, the ladder incorporates a servo-controlled boom to ensure that the cat is almost completely free of any restraint or drag which might otherwise be imposed by leads carrying foot contact, electromyographic and neuronal signals from the animal to the recording equipment. The apparatus is proving in use to be reliable and easy to operate, and our preliminary results clearly implicate supraspinal motor centres in controlling the skilled and adaptive behaviour which the ladder requires.