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Holly Stewart's picture

Limiting Factor in Our Sensible Reality

I’ve been thinking a lot about these action potentials, and they seem quite interesting to me. We seem to be able to describe how they work, and somewhat even why they work (i.e. because of a stimulus). But my question now is: knowing all of this, are action potentials the limiting factor/the limiting component in our experience of reality? Let me explain where this question is coming from, because it seems a bit out there, I know…

Last week we talked about how action potentials work, they are a moving battery that propagates down an axon using selective membrane permeability and concentration gradients. On Thursday we furthermore talked about what makes action potentials work. We have a resting potential, which is effected when it is exposed to ions such as sodium and calcium and if there are enough ions present, a threshold is reached and an action potential is produced. Okay fine. I’m really okay with things up to about this point. But did anyone ever consider how complicated this simple system is?

Evolution is a conserved process: if it works and the environment supports it, then don’t try and fix it. So evolution has created this system relying on concentration gradients, membrane permeability, calcium, sodium and potassium; and it seems pretty lucky that all these ions are hanging out in the right concentrations right around the neurons so that when there is a stimulus action potentials can be created. But what happens when it doesn’t work? I spent a good couple of hours scouring the web (specifically PubMed) for scientific research showing what happens when these factors (ions, membrane permeability, etc.) are there: things don’t work. Well that makes me a bit uncomfortable. Granted adaptation happens over time, but evolution has given full responsibility to these ions and principles alone, across all the different types of neurons (motor, sensory, interneurons). The system is dependent on everything functioning as it should.

We (humans) are such an intricately designed system, extremely refined and well-developed, but so much so that it seems highly unlikely if not impossible for us to adapt. What happens if calcium stopped being transported and localized near our neurons? What would happen if the sodium/potassium pumps stopped working? Well, it may seem easy to say that we would die, but I want to even take a further perspective and say that evolution has already made some decisions for us. Evolution has already decided which ions it likes and which principles to base the system of action potentials off of, and it is going to keep using that system as long as the environment supports it. But, what if the system we are using has dictated the reality that we are able to be sensitive to? I would argue that it has.

For me then, it doesn’t seem that odd that we are only able to be sensitive and experience such a small piece of reality. Evolution has made a choice in humans, just as it has in birds and dogs, and I’m not really interested in speculating if that choice was good or bad, simply realizing that it has been made. I’m sure what made evolution respond the way it did or what implications it has, but I do think it is interesting to think that action potentials may in fact be the limiting factor in our sensitive and experiential reality.


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