Asked by dannyl on 1 May 2020.
    • Photo: Kim Liu

      Kim Liu answered on 1 May 2020: last edited 1 May 2020 10:03 am

      I’m going to leave whether or not this is possible to someone else haha – a quick look around the internet seems to suggest in principle it is possible! Certainly someone wanted to try it a couple of years ago! I personally think it might just be too complicated to ensure all the connections are recreated accurately, but I don’t know.

      From an ethics point of view (which is more interesting for me!), scientists and doctors agree that it is completely unethical to attempt medical procedures on human subjects which are likely to cause radically unknown outcomes, unless there is a lot (A LOT) of reason to think the subject’s life will become substantially better. This stops most genetic engineering experiments being done on human volunteers, because it is too difficult to know the full effect of changes to the genetic code.
      Most likely, a head transplant subject will just die, but what if the patient ends up worse than dead? We have no idea what will happen to the person’s mind – the biological origins of human personality, beliefs and general consciousness are (to my knowledge) completely unknown to science at the moment. What if the operation affects the brain so that it constantly thinks the human is in pain? What if the subject becomes a criminal after the operation – who’s fault would any crimes committed there be? What happens if they have children – who would the children be related to?
      From this point of view, I think head transplants will be considered unethical for many, many years to come!
      I’d love to hear yours and others’ ideas!

    • Photo: Shenghong He

      Shenghong He answered on 1 May 2020:

      Hi, I do think it is possible to repair, or rehabilitate the spinal cord, although it would be very difficult. Many spinal cord injury (SCI) caused paralyzed patients will accept long-term regular rehabilitation exercise, which could help them slowly improve the impaired movement functions. To complete a movement, we first need the brain to produce an intention or a command of doing this movement, then we need the spinal cord and other neural circuits to transfer this commend to the corresponding muscles for operation. If the spinal cord is injured, the signal would not be able to arrive the muscles, thus, the movement could not be carried out. Recently, scientists have been working on investigating the possibility of using neural interface and electrical stimulation to bypass the injured spinal cord, in order to rehabilitate the impaired motor function. The idea is to get the signal before the injured spinal cord segment, use a model to analyse the output would it be if the spinal cord is not injured, and use electrical stimulation to simulate this output and deliver it to the adjacent spinal cord segment. This technique has been tested on monkeys and the experimental results are very promising.

    • Photo: Carolina Coelho

      Carolina Coelho answered on 1 May 2020: last edited 1 May 2020 10:58 am

      It is possible in theory, but very hard to do.
      One thing that scientists and medical doctors are doing is to cure paraplegic or tetraplegic injuries. These injuries mean that people can no longer move their legs (paraplegic) or their arms and legs (tetraplegic). This is because their nerves can no longer transmit information to their muscles which move the limbs.
      Some cures are to use electrical wires and chips, similar to what we use in computers and phones to replace the faulty nerves. Other cures involve curing and healing the broken nerves and scientists are using for example nerve cells from our nose or from other people to try and heal the injured nerve. Another important thing is to try to teach your brain again – the brain needs to be reprogrammed so that it knows that you just put a new part in. This can be done with physical therapy and also with games! Games are a great way to programm new things into your brain.

      Once we know how to cure these injuries we may want to cure bigger injuries, which ultimately may mean brain transplants. But I think it will be centuries before we can do that.

    • Photo: Lidia Ripoll Sanchez

      Lidia Ripoll Sanchez answered on 1 May 2020:

      Hi dannyl, I work in neuroscience and this is actually a very interesting topic. In some organisms like zebrafish, spinal cord injury can be repaired, and it actually happens very fast in 6-8 weeks a clean cut of the spinal cord can be repaired. The main problem for spinal cord repair in mammals is that the nerves cannot regrow as they do in zebrafish. Thanks to studies in zebrafish they have identified genes that are essential for regeneration for example several cell-to-cell communication genes. However they still don’t know exactly all the molecular mechanisms that allow this fish and other species to be able to fully regenerate nerve damage.
      But I don’t think we are so far from doing it in humans. They have already developed biomaterials that can act as a scaffold and guide the nerves to regenerate in humans, which seems to be essential. They are still missing more information in how to make human nerves regrow like zebrafish nerves and make our brain accept them as normal, but the more they research this in zebrafish the closer we will be to solve that in humans.
      I’ll leave you here some videos about how this happens in zebrafish, it’s fascinating: https://www.youtube.com/watch?v=XCGWfR4Yk5g

    • Photo: Nina Rzechorzek

      Nina Rzechorzek answered on 1 May 2020: last edited 1 May 2020 1:26 pm

      Hi dannyl, there are lots of trials happening to try and repair a completely transected spinal cord in humans, but evidence at the moment suggests we still have quite some way to go before this is really possible. Lots of ethics to consider (more so for the brain than the spinal cord). I would not be in favour of transplantation of either of these regions over endogenous repair (I think it would be better to find a way of regenerating/repairing our own brain/spinal cord tissue). This of course has ethical implications too – what if the repair goes out of control and the patient ends up in a worse situation than they started with? Less severe spinal cord injuries can actually be ‘repaired’ if treated effectively – I’m thinking mostly about ‘slipped discs’ that press on the spinal cord causing weakness or paralysis – we can sometimes achieve full functional recovery of a paralysed dog if we surgically remove the offending disc material – but it’s all about how bad the injury was to start with and how quickly we can ‘relieve’ the compression. It’s very satisfying seeing a paralysed patient walk again – but that doesn’t remove ethical considerations – we have to weigh up the benefit to the patient against the risks of surgery and the stress to the animal.