Head transplants move toward the future

Imagine waking up from a long period of unconsciousness only to find your head bolted down,… Imagine waking up from a long period of unconsciousness only to find your head bolted down, unable to move and someone else’s heart feeding blood into your neck and brain.

This is what you would awake to after a successful head transplant.

The procedure recently marked its 100th anniversary — 1908 witnessed a semi-successful attempt at grafting one dog’s head onto the side of another dog’s neck. Because too much time elapsed between removal of the dog’s head and reattachment to the new dog’s circulation system, it ended up only able to perform basic reflexes like pupil dilation and tongue movement.

In 1963, Dr. Robert J. White of Case Western Reserve University transplanted a monkey’s head onto another monkey’s body, successfully enabling almost all the monkey’s fundamental senses upon regaining its awareness. Doctors in Japan have done similar experiments with rats, and with a high degree of success. In a controversial 2001 operation, White successfully repeated his original experiment with another monkey, managing to keep it alive for days after the operation.

Still, it is one thing to read about the transplant. It’s another to witness the archive footage of the monkey awakening from its anesthetic-induced sleep and trying to figure out the immediacy of its new situation.

Human face transplants have recently been attempted, with some degree of real success, and a lot of people would like to see if researchers somewhere will take the next leap and perform a head transplant on humans.

It might sound a bit farfetched, but most of the technology to make this happen already exists, albeit in a relatively primitive state.

But for all the absurd scenarios you can dream up involving the idea of head transplants, the current options are rather limited. Without the ability to reattach severed spinal cords, all the animals ever tested have lost motor function below the neck.

One critic of the procedure, Dr. Stephen Rose of the Open University, has called the experiments ‘scientifically irrelevant.’ Without the ability to regenerate severed nerve connections in the spinal cord, the newly transplanted head does not possess the ability to exercise control over its newly attached body.

‘All you’re doing is keeping a severed head alive in terms of the circulation from another animal,’ claimed Rose. ‘It’s not connected in any nervous sense.’

If Rose is correct, and the reattachment surgery is little more than a roundabout way to keep a head alive without motor function, is there anything to justify continuing the research?

Some quadriplegics think so. For those who have already lost motor function from an accident or disease, there isn’t as much to lose from the procedure. Imagine it is possible — ethical and technological issues aside — to perform a head transplant on humans. Gaining a whole new body full of healthy parts in one operation could be viewed as a better alternative to receiving numerous, complicated organ transplants one at a time.

And in combination with the remarkable advancement of brain-computer interface devices (BCIs), which allow the brain to communicate with prosthetic limbs or other external devices, it might not be such a reach to consider human head transplants as a potentially real form of experimental medicine within the next few decades. There are already BCIs that can partially restore sight to the blind and allow victims of partial paralysis to control prosthetic limbs directly through their thoughts.

One of the most advanced BCI developers is Pitt neurobiologist Andrew Schwartz, who in 2005 demonstrated a monkey trained to feed itself with a robotic arm controlled through one of the BCIs his team created.

Perhaps a logical pairing would bring these BCIs together with the results of a successful head transplant, with BCI abilities replacing or even someday enhancing the natural abilities of a limb. Subsequently, it will be examined whether or not these types of procedures could be used to benefit humans. How does one even begin to address the issues about morality and personal identity it raises? At the very least, we have a new twist on the Ship of Theseus puzzle.

We’ve already seen the general reaction to other bio-ethical debates, such as cloning and stem cells. As our technology advances, the problems turn from empirical to ethical: We know we can, now should we?

E-mail Brandon at bkp3@pitt.edu.