Artifical Limbs and Pain


I recently read that some scientists had discovered a way to give an artificial hand a sense of touch. It is very limited at the moment, but the major obstacle (sending artificial signals to neurons) has been surmounted. Significant improvements are likely in the near future.

This is an unusual opportunity for those of us who still have working biological hands. We finally have a chance to address one of the long-standing questions in the problem of evil discussion empirically: Is it possible to design sensations that a) will prevent people from doing things that are harmful to their bodies and b) are not painful. Paul Brand's work with leprosy patients suggests no, but those experiments were very limited. Soon we (as a society) will conduct a much better experiment. And where their was previously speculation, there will be fact. Glory be.


A friend of mine pointed out the following:
Such implementations could become addictive. If one were to feel pleasure when ever one wasn't doing something "bad" what would the subjects response be if you tried to take that away. This idea sounds kind of like Soma from brave new world who is controlling the supply?

I am assuming "not painful" to mean pleasure.
My responses were:
  1. Not painful does not imply pleasurable. Most of your body is reporting neither at any given time.
  2. By my understanding, you have no "pleasure" sensors in your body. Instead, you have sensors for pressure, temperature, electric shocks, etc. and your unconscious brain assembles these into different sensations base on context. Mild heat across your upper back will probably be interpreted as sunlight, which might feel good depending on whether you are currently cold. At a bit of pressure and you feel like you are leaning on something warm. Add the knowledge from other senses (e.g. vision) that your girlfriend is beside you with her arm out in that approximate direction, and the same heat and pressure signals now feels really good.

    Pain is a bit simpler. I think some signals are always painful (e.g. electric shock). Also, it is possible that some of the others could be interpreted as painful in some circumstances (e.g. sunlight on a very hot day). You may also have some sensor for "my body has been structurally damaged here" (e.g. if you cut yourself), or possibly your body determines this from the sudden secession of signals (or a special "connection lost" signal from the remain portion of the nerve).

    Note: This is based on what fragments of neuroscience I have stumbled upon while looking at other things. I am not an expert in this area. Reading a bit on Wikipedia leads me to 3 conclusions:
    1. touch sensors (the kind I this was about) are not that biologically distinct from other senses (including ones I don't even know what are).
    2. Neurons are divided up by at least 3 crosswise systems, including where they are and how they are connected (this one is in your skin and sends signals), what they do (respond to cold), and what effect them doing this has (pain).
    3. Even scientists don't fully understand this stuff. It is very involved.
  3. Pleasure sensations are much trickier to create than pain ones. Pain can be produced by stimulating many (all?) neurons above the danger level (e.g. the feeling of a powerful electric shock). Pleasure is context-dependent and probably requires more fine-tuned "volumes". Also, I doubt that it would be possible to get many more pleasure sensations out f an artificial hand than a natural one, given that the same nerves are being used.
  4. Addiction (your actual point): I would assume, in practical terms, that the supply would end up controlled by the person with the artificial hand, as he is the one carrying it around. I am not sure how anyone else could get control. You could do it with a remote control circuit, but it would have to be installed with the hand and I suspect it wouldn't happen. For instance, we do not install "remote kill" switches in pacemakers. Correction: Pacemakers theoretically can be hacked.

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