I once attended a neuroscience conference featuring a talk about spinal cord injury. The presenter showed a brief video clip that haunts me still to this day. The presenter showed a clip of his experiment in which he had crushed a cat’s spinal cord and was recording the cat’s movement on a treadmill. He had forcibly implanted electrodes into the cat’s brain and she was struggling to keep upright, dragging her paralyzed legs on the treadmill. She repeatedly fell off the machine. At one point, the experimenter lifted her up to reposition her on the treadmill and the cat did something that was utterly unexpected. She rubbed her head against the experimenter’s hand.