Some features of our lives just seem inviolable. Most people would never worry about failing to recognize objects they see every day, or beginning to believe that their arm does not belong to them. And yet, these are exactly the types of things that can go wrong. Body and brain functions are not physical laws like those of thermodynamics or relativity. Gravity may be here to stay, but when it comes to our behaviors and perceptions, we may be justified in being a little more nervous. So what would you do if you lost control of your own arm?
If I ask you to lift your arm, and you agree to participate in the exercise, you’ll probably see your arm start to rise. But you always feel that the arm is doing what you, as a conscious agent,want it to do.
Anarchic hand syndrome is a disturbing disorder in which patients lose the normal experience of voluntary movement. An arm can begin to move and act without the patient wanting it to, as if the limb has a will of its own. In fact, a patient will often begin fighting their own limb if it becomes uncooperative, trying to stop it from grabbing at their tissue while they blow their nose or from touching the person sitting next to them. Have a look at this video demonstrating the plight of an elderly patient in her hospital bed after she suffered a severe stroke.
In the most extreme cases, your own anarchic limb can try to kill you. One patient described her hand tearing away at her bedcovers in the night and grabbing her own neck to strangle her. The only sense she could make of her horrifying condition was to assume that her limb was possessed by an evil spirit.
Patients with anarchic hand syndrome are in the bizarre situation of knowing that their limb is their own but losing all sense of agency over it. Without the normal process of intending to perform an action, it’s hard to say that you turned on the light when you flick the switch. Your arm certainly did it. But not you.
It all links back to our sense of who we believe we are. When we use the words “I” or “me”, we normally refer to our conscious minds and experiences. It would be strange to say “I am beating my heart faster” after going for a run, even though the heart is a part of our own body. We simply say “my heart is beating faster”. But when it comes to lifting our arm, we say “I am lifting my arm”, not “my arm is lifting”. The difference all comes down to our sense of consciousness and intention. Our heart rate is automatically controlled behind the scenes of our awareness, so although we are educated enough to know that we own our heart as much as we own our arm, we don’t talk about heart activity as a product of our control.
So in a sense, when we have anarchic hand syndrome, our arm becomes more like our heart. The arm is on us and it is a part of us. But we are not in control. The labels “anarchic hand syndrome” and “alien hand syndrome” are often used interchangeably, even in academic papers. But some researchers distinguish between them, explaining that patients believe anarchic hands belong to their own body even when they cannot control them, while alien hands are experienced as a completely disowned limb.
Anarchic hand syndrome typically follows extensive damage to motor-related areas towards the front of the brain, including the anterior corpus callosum and supplementary motor area. Alien hand syndrome usually features damage further towards the back of the brain, including the posterior corpus callosum and parietal areas. The symptoms can also arise from degeneration in the circuits that connect areas of our cerebral cortex with the basal ganglia, a system that is critical in allowing us to move smoothly and effortlessly.
During movements of an anarchic hand, the primary motor cortex in the brain — one of the final command centers for sending “move” signals to your limbs — is fully activated. But unlike with voluntary movements, that activity is practically isolated, appearing without the normal co-activation of premotor, prefrontal, and parietal areas that are so important for our experiences of intention and movement awareness.
Utilization behavior refers to actions that appear fully functional, but emerge habitually and automatically in the wrong environments. They can occur after lesions to frontal areas of the brain, similar to anarchic hand syndrome, but patients often do not comment on their actions being out of the ordinary (unlike the woman with the anarchic hand in the video linked above, who repeatedly complained about her arm). When a patient sits in a doctor’s office, and sees a pen and paper sitting on the table, they might pick up the pen and begin to write. When they see a pack of cards, they might deal them as though they are about to start a game with the doctors. None of these actions have anything to do with the doctor’s instructions. Even when the doctor says that the objects should not be touched, the patient returns to their action after a small distraction. The patients simply use the objects because they are there.
Some theories of motor behavior explain that whenever we see a manipulable object in our environment, our brains automatically prepare the relevant action for handling that object. When we see a hammer, we initiate a motor program for a palm-grasp action. When we see a grape, we initiate a program for a smaller precision grip with our fingers. Thankfully, under normal conditions, we have the control systems in place to suppress those action plans when they are contextually irrelevant (although, when I spot a delicious bunch of grapes in a bowl, I often struggle with that suppression). Efficient hammering is great when we are putting together furniture, but not when we are in a doctor’s waiting room. When the control systems in our brain are destroyed, particularly following frontal damage, we may find ourselves acting for the sake of acting.
When you read enough about brain dysfunctions, it begins to seem as though there is nothing in your life that you can depend on. We should remember that disorders like the ones described above are incredibly rare. And on the plus side, they can inspire us to appreciate some of the smaller facts of our existence. Even on your most boring day, you probably achieved several minor miracles of purposeful action and awareness. The notorious 3-pound organ sitting in our skulls can cause us grief during testing times, but it also makes life worth living the rest of the time.