The story of your brain: why you are who you are

'Every time I hold a brain, I am completely in awe and wonder. It's three pounds, and somebody's entire life took place inside of that.'

David Eagleman, a leading neuroscientist at the Baylor College of Medicine in Texas, researches the neural basis of perception, addiction, and synaesthesia. He describes the brain as being like a city.

'If you were to look at a major city and say, "Where is the economy of that city?", you would see that the question is misplaced—you can't really see a spot where the economy is located.'

Similarly, the conventional understanding of why someone is the way they are can often be misguided.

'We traditionally have approached this by looking at, let's say, the person's history. Really, their biology is the whole story about who they are.'

Our biology, Eagleman says, is a confluence of our genetics and early experience, neither of which we exercise much free will over.

'Your genetics happen before you are born. All the important experiences that shape your brain happen in the first few years of your life.'

Read more: Neuroplasticity—how the brain can heal itself

The brain also possesses the ability to evolve and relentlessly rewrite its own circuitry based on new experiences.

So while half of who we are stems from our genes, the other half is based on what is happening to us.

Our conscious awareness, however, lags behind what happens in the physical world; we're forced to rapidly assemble a reality.

'Almost everything happening in your brain you have no conscious access to,' says Eagleman.

'It lives below the level of your acquaintance or your consciousness, but also your thoughts and how you think about things.'

And when it comes to decision making, Eagleman says we're far from rational beings. Instead of carefully weighing up a considered list of pros and cons, the brain instead resembles a machine made up of conflicting and competing networks.

The neuroscientist believes we trick ourselves into thinking we have one single sense of self when in reality our brain is comprised of boundless components.

'The right way to think about the brain is to think about it like a neural parliament, where you have all these different parties fighting it out to steer the ship of state, to control decisions.

'When we look at the conflict that happens in decision making, who you are emerges from the brain-wide battles for dominance that rage inside of your skull every moment of your life.'

Read more: The mind's role in healing

Looking ahead to the future of neuroscience, Eagleman suggests we are at a moment in history when the marriage of our biology and technology will transcend the brain's limitations.

Eagleman's own laboratory has developed a vest through which people can 'listen' to data streams through the skin of their torso. The first people to have tried the vest are deaf.

'By turning sound into patterns of vibration on the torso, they can figure out in a real-time speed of patterns how to make sense of these, how to hear through the skin of their torso.'

It's important to remember, Eagleman notes, that all humans ever do when we 'hear' sound is convert patterns of sound compression waves into electrochemical signals, which we then translate into perception.

So far the laboratory has had success, with researchers able to show that deaf people can learn the language of the vest in order to hear the sound of the world around them.

According to Eagleman, this is just the beginning.

'We are feeding all kinds of data streams—weather data or stock market data—directly into the vest, and people can come to have a perceptual experience of that.'

But with great potential comes great responsibility; to follow strict ethical and moral guidelines, ensuring a positive and humanitarian future.

'The important part for us is to stay one step ahead of the ethics on that, to make sure that we are at all times keeping abreast of what is the responsible thing to do.

'Our species is just now discovering the tools to shape its own destiny, and what we become is up to us.'

An exploration of all things mental, All in the Mind is about the brain and behaviour, and the fascinating connections between them.