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The nature of consciousness is one of the most heated debates in neuroscience.
Scientists can’t seem to agree on anything when it comes to consciousness:
what it is, why it happens, how it happens, or even if it matters.
Consciousness in the sense I’m talking about isn’t just being awake.
It’s also our awareness of the world and the way we subjectively experience it.
So scientists have put their heads together
to figure out how our brains manage this incredible feat.
There are tons of different theories of
what type of brain activity causes consciousness.
Some of them rely on specific brain areas,
like the prefrontal cortex, thalamus, or anterior insula.
Others focus more on the rhythm of neurons firing, which neurons fire together,
or the way networks of neurons interact with each other.
And some link consciousness to chemical messengers,
like dopamine and GABA, in the brain.
One of the problems with all of these theories is that not all brains are the same,
and brains can even change over a person’s life,
but that doesn’t necessarily make someone less conscious.
In some people, those brain chemicals might be more or less active.
Sometimes babies are born with entire parts of their brain, just...missing.
And some people experience brain injuries or diseases that
damage and destroy massive amounts of the brain.
Like...almost all of it.
But while these can have significant effects on people’s lives,
a lot of people with these conditions aren’t any less conscious than anyone else,
or any less conscious than they used to be.
Lots of brain functions are plastic, meaning that if a critical brain area
gets damaged or destroyed, the brain can rewire
and reorganize itself to compensate for that damage.
So, for example, a lot of people who are blind
actually process some sounds in the visual parts of the brain.
So maybe consciousness is plastic, too.
But that would mean that consciousness
isn’t just some inherent property of specific neural firing patterns.
It could mean that consciousness is something our brains learn.
And keep relearning.
This is called the radical plasticity theory, and it was originally proposed in 2011.
The idea here is that two things are necessary for consciousness:
knowing what’s going on inside you and
having some sort of emotional response to that information.
So it’s not just a thermostat that registers
that the temperature is below a set point and turns up the heat.
There’s an aspect of knowing that you know it’s too cold.
And think about emotions when you look at something green.
Part of the experience might be associating it with the color of your first car,
the feeling of jealousy, or a stoplight signaling “go.”
And both of these factors, being aware of what’s going on
inside you and having an emotional response to it, require learning.
And learning requires plasticity.
Learning comes down to strengthening
and weakening connections between neurons.
And as they say, neurons that fire together, wire together.
Everything we experience is represented in our brains by patterns of neurons firing.
So if you see a dog, a pattern of neurons in your visual system
that represents the shape of the dog will start firing.
Then at some point, you see a dog shape,
and someone points and tells you it’s a dog.
The visual representation of a dog is now linked to the concept of a dog.
And in the future when you see a dog, both the visual representation
and the conceptual representation will be activated.
Now let’s say you’ve been bitten by a dog a couple of times.
So now when you see a dog, that visual representation and
conceptual representation go off, but you also have fear signals firing with them,
strengthening the connection between dog and fear.
And by that point, you’ve learned a neural representation of “dog” that includes
what a dog looks like, what a dog is, and that you should be scared of them.
So back to radical plasticity theory.
In this idea, the brain is learning in a few different ways at once.
First, it’s learning the basic neural representations of things.
Then, it’s learning the fact that we have representations of those things
and the fact that those representations are /tied/ to experiences and emotions.
So we end up with representations of the representations.
And with this hypothesis, our brains are both
constantly learning and learning what they know.
In other words, we’re always learning and relearning consciousness.
And so, if part of our brain is damaged, we don’t necessarily lose consciousness,
because what’s left of our brain just learns how to be conscious on its own.
So consciousness may not actually be set in stone.
We may not be born with it in its final form.
It may actually be a constant, evolving process.
And that is a pretty cool thing to be aware of.
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Thanks so much for watching this episode of SciShow Psych!
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