Here’s probably the most basic question in all of sensory neuroscience (the study of the senses). How does a ray of light enter our nervous system, to eventually become something that we see? How in fact does anything external (anything we touch, smell, taste, hear or see) get turned into something internal (some kind of signal in the brain that tells us to sense something).
The answer is simple, so simple in fact that it is one word:Transduction.
OK fine, it’s a simple answer if you know what transduction means. So I’m going to explain it to everyone now.
In a sentence, transduction is the conversion of one form of energy into another. Try to think back and remember the different types of energy:
- Gravitational potential
- Elastic Potential
Now lets lay these out in relevance to our 6 senses (and we do have 6, the last one is just a bit of a debated secret).
- Gravitational Potential (kind of)
- Elastic potential (again kind of)
Taste and Smell:
Self (our awareness of where our bodies are):
- Elastic potential.
These are all the main types of energy that we can sense. Now here’s the problem:
The nervous system only uses one type of energy, and that is electric.
Therefore if we the brain is what allows us to sense the outside world, all of these energies we mentioned previously have to be converted into electrical energy so they can enter the brain. That is where transduction come in.
In all of our sense organs (eyes/ears/tongue etc.) there are nerve endings which contain hundreds and thousands of receptors. Each organ will have different types of receptors that will react differently to each type of energy.
In the eye there are ‘photoreceptors‘. When light touches these receptors they undergo a sudden reaction which generates electrical energy.
In a similar way there are ‘chemoreceptors‘ in the tongue and nose which will react to chemicals and generate electrical energy.
The skin and ears use ‘mechanoreceptors‘ which are physically moved, either by us touching something or by us hearing something. When they are moved these receptors open up, allowing electricity to enter.
As you can see all of these receptors convert one form of energy into electrical energy. Thus these receptors ‘transduce‘ the energy, allowing us to sense them!
There you go, now if anyone ever asks you how we can sense things, just say: Transduction!
I might do another basic sense post before moving onto the specific senses themselves. Just to warn you!