4 The brain at work

Using the variety of techniques that you met in the previous section, scientists have found that neurons are connected to form neural pathways and circuits. Usually, neural circuits in different regions of the brains are interconnected in complex large-scale networks, working together to accomplish tasks such as talking. As a result, contemporary neuroscience is moving further away from the picture of small and isolated regions of the brain being solely responsible for different roles, as discussed at the beginning of Section 3.

Connections between neurons are constantly being either reinforced or abandoned depending on how much they are used. Pathways in the brain are formed in this way, allowing new skills to be mastered and memories to be created. This is called ‘synaptic plasticity’. This remarkable ability of the brain to change with experience, continually adapting and learning, is a key area of current neuroscience research.

Here it is in action in a very striking way:

Download this video clip.Video player: Video 9

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Transcript: Video 9 The rubber hand illusion

[MUSIC PLAYING]

LAWRENCE ROSENBLUM

Hi.

EDIE

Hi.

LAWRENCE

I’m Larry.

EDIE

Hi. Edie.

LAWRENCE

Very nice to meet you, Edie. We’re going to do a little demonstration here called the rubber hand illusion. It’s going to be a little--

NARRATOR

This illusion may look like fairground fun, but it reveals one of the most important new ideas in brain science.

LAWRENCE

Right there. Good, and can you put this hand down right over here, and just curl it up like the rubber hand’s curled up a little bit. All right, now what I’m going to do is try to position the rubber hand so it looks like it’s your own. Okay, could you imagine that being your own hand, kind of?

EDIE

Yeah.

LAWRENCE

What we’re going to do is we’re going to stroke your fingers simultaneously, the rubber finger and your real finger. And hopefully this will convince you that the rubber hand is your own. That your brain will actually adopt this hand.

NARRATOR

In the illusion, simply watching the rubber hand being stroked at the same time as the real hand is enough to trick the brain into adopting it as its own.

LAWRENCE

We like weird. And slowly but surely, you should feel that the hand you’re looking at is actually part of your body.

EDIE

Feels like you’re touching my hand with that one.

LAWRENCE

Right, sort of feels like this is your hand that I’m touching, right?

EDIE

Yeah.

[HITTING RUBBER HAND]

Oh-oh.

[LAUGHTER]

LAWRENCE

You okay?

EDIE

Yeah.

LAWRENCE

Good. Try that at home with your kids, yeah!

The rubber hand illusion is a wonderful example of how multi-sensory perception can influence how we perceive our own body. I mean, that’s how deep multi-sensory perception runs. When you hold your hand out, it’s generally thought that you know it’s there because of the information you’re getting from your muscles and your tendons, and that sort of thing. But what the rubber hand illusion does is show how that can be overridden by visual information.

NARRATOR

The rubber hand illusion shows the powerful connection between what we see and what we feel. But it reveals even more than simply the way our senses are connected. It hints that a fundamental change in the brain is taking place.

MAN

Oh!

[LAUGHTER]

LAWRENCE

Isn’t that strange?

MAN

Yeah, that’s creepy.

LAWRENCE

So, what might be going on in the rubber hand illusion is that the brain is actually changing to accommodate the new rubber hand, going through some sort of structural change that we call ‘neuroplasticity’.

NARRATOR

Neuroplasticity is an exciting new idea that suggests the brain can change in response to experience. And this is what’s taking place in the rubber hand illusion. The brain may be temporarily rewiring itself to adopt the plastic hand as its own.

LAWRENCE

Really feeling like it’s your hand now, huh?

WOMAN

Yes.

LAWRENCE

Is that a little weird?

WOMAN

Yes.

LAWRENCE

Yeah, we like weird in perceptual psychology. There we go.

[HITTING RUBBER HAND]

LAWRENCE

Was that scary?

WOMAN

Yes.

LAWRENCE

Good, we like that.

Brain plasticity is a terrifically exciting sort of phenomenon for perceptual psychology. I think the rubber hand illusion shows that. That the brain can change based on a new experience. And this is important for somebody, say, who doesn’t have vision, to know that they can compensate through plasticity with another sense, and use that to navigate the world.

NARRATOR

This idea of a plastic, flexible brain is so exciting because of the phenomenal possibilities it contains. Not only do our senses work together, but it suggests one could be used to replace another.

End transcript: Video 9 The rubber hand illusion

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Video 9 The rubber hand illusion

It’s perhaps possible to appreciate how something relatively simple – like learning to count – could be programmed into the brain. But what about something more difficult, like learning to play a violin concerto from memory? It takes years of practice with the instrument, of course, but just think of everything the brain must store to achieve this task: the minute muscle movements, the sounds, the extraordinarily complex patterns of notes. It’s truly wondrous to consider the brain at work.