Miércoles 17 de Octubre de 2007, Ip nº 212

Opening up your mind
Por Kate Wighton

“Your brain operates on a need-to-know basis and most of the time you don’t need to know.” This is how Professor Chris Frith, a neuro-psychologist from University College London, sums up the relationship between our brains and our minds.

And he puts forward a mind-boggling prospect: the majority of the work that your brain does goes on unconsciously. In fact, your whole world, your consciousness, your reality, is an illusion, created by our brains, every one of which constructs them slightly differently.

Professor Frith, along with other leading brain experts, this week was examining the topic of consciousness and the mental world in which we live, at this year’s British Association for the Advancement of Science Festival in York. Their starting point was that our brains are constantly soaking up and processing information from the world around us, monitoring, checking and assessing. But most of the information from our 100 trillion or so brain cells never reaches us. Instead the brain takes this raw data to create a model of the world and this is the mental world in which each of us lives.

Using noninvasive brain-scanning equipment that provides a window on the brain, clearly showing which brain areas are being used, scientists are gleaning insights into the parts of our brains that produce our conscious selves. The researchers are using this knowledge to gain insights into what happens when we lose consciousness – if we’re in a coma, for instance, or under anaesthetic – and to help people with mental disorders and distortions of consciousness, such as schizophrenics.

So, if only a small amount of our brain activity is used to generate our personality, and our worlds, what is the rest doing, and why don’t we use it? The answer, according to Professor Frith, is that if we did use all this information, it would simply put our consciousness into meltdown; we wouldn’t be able to handle it. “We can unconsciously bring together information from many different sources, without thinking about it at all,” he says.

Professor Frith, who wrote a book on the subject called Making Up the Mind: How the Brain Creates our Mental World (Blackwell, £14.99), says that if we start to think about how we do things – for example if you start thinking about how you physically move your limbs, or how you actually understand the meaning of these letters on the page – you start to get a bit confused and your brain doesn’t work as well.

What’s going on inside our heads?

The brain’s ability to act on its own, without any conscious interference by you, may be an evolutionary hangover that helped us to survive, says Professor Frith. For example, if you see a snake in your path you immediately jump out of the way before you’ve had time to consciously think to yourself, “Eek! Snake in my path”. If you did think about it, in the time spent assessing your actions, you probably would have been bitten. So how have scientists worked out that most of our brain activity is unconscious, and what is actually going on inside our heads?

To answer the first question, Professor Frith says the fact that we can do many skills at once – for example, driving a car, while thinking about something completely different, such as what to buy for dinner – has suggested that there are many conscious levels in our brain. And recent experiments using the brain-scanning technique fMRI, which pinpoints active brain areas, has confirmed this.

“In one of my experiments we showed a group of people a pattern on a computer screen, while scanning their brains. We then flashed up an image of a scared-looking face, just for an instant. We asked them if they had seen a face, and, because it was only on the screen for 100th of a second, they said no. However, our results showed that their brain had seen the face. The amygdala, the area associated with fear, had suddenly become active,” says Professor Frith.

A brain of two halves

This experiment confirmed that our brains take in much more information than we realised and that we see only a very small part of it. So does our brain physically contain conscious bits and unconscious bits? Roughly speaking, yes, says Professor Frith. “The back of the brain deals with perception and the front of the brain deals with action,” he says.

Through brain-scan experiments, scientists believe that our consciousness is created by an interplay of the front and back halves of our brains. The front half is where our memories and intentions lie and it seems to be the area responsible for creating our personalities. The back half is responsible for monitoring our environment and it constantly takes in information about our surroundings. However, because of the sheer volume of data that it absorbs, it only bothers to tell the conscious part, the front section of our brain, if something is out of the ordinary and deserves attention.

Dr Peter Naish, of the Open University, studies what happens in the brain when consciousness is distorted. He scans the brains of people under hypnosis and compares these to brains of patients suffering schizophrenia-induced hallucinations. He believes that faulty connections between the front and the back areas cause hallucinations. “The two areas get out of kilter in schizophrenia, so that the unconscious part of the brain is feeding through information to the conscious part and making it believe that it is a reality when, in fact, it isn’t.”

Dr Adrian Owen, a neuroscientist from Cambridge University, scans the brains of patients in persistent vegetative states, mostly from head injuries. Although their eyes are open and they can smile, they cannot communicate, and until Dr Owen’s work, it was impossible to tell whether or not they were conscious. Through brain-scanning he is trying to find a way of determining whether people in persistent vegetative states (PVS) are conscious, and whether people have any levels of conciousness when they go under general anesthetic. He hit the headlines last year when he showed that a PVS patient did show conscious brain activity. He asked the patient to imagine playing tennis and areas of her conscious brain became active.

Are patients conscious under anaesthetic?

Dr Owen says that the patient in his study was an exception. And from his work he believes that PVS patients with this level of consciousness are rare. And what about decisions on when to pull the plug on comatose patientss, who are suspected to be brain-dead? Could the scanning help with this? Dr Owen thinks not. “In these cases, doctors can usually see from pictures of the brain that it is badly damaged and could never harbour conscious thought.”

He is focusing on healthy patients under anesthetic and has discovered that, although their brain is very active, it is only in the unconscious area. “When we speak to people under anaesthetic the part of the unconscious brain that recognises speech becomes active. However, the area that understands and processes it in the conscious area remains still. Therefore, the brain hears us but it doesn’t compute it.”

We’ve a long way to go, says Dr Owen. “Twenty years ago we had no idea about the amount of brain activity that happens unconsciously. We now realise that a huge amount goes on without our knowledge but we still don’t completely understand the nature of consciousness.”

Inside your head

At any one moment your brain is receiving about 100 million pieces of information through the ears, eyes, nose, tongue and touch receptors in the skin.

It consumes about 10 watts of power per day. If scientists tried to build a brain of silicon chips, they think it would need around one million times more power.

Your brain weighs 1.5kg and has a texture similar to that of a mushroom.

If you were to stretch out all the nerve connections in your brain, they would reach a distance of about 3.2 million km.

  15/09/2007. Times Online.