Responses of motor cortical neurones in the cat to unexpected perturbations of locomotion.

Extracellular recordings have been obtained from individual motor cortical neurones of cats walking along a horizontal ladder. We present responses obtained when selected rungs dropped unexpectedly by a small amount beneath the animal's weight. Our results show that forelimb motor cortex is rapidly and in graded fashion informed of such events, which may produce appreciable changes in impulse activity in the corticospinal tract.