Dr Norman Swan: And speaking of the nervous system, let's go into a neurosurgical operating theatre, where a person needing brain surgery is lying on the table with his brain exposed - while he's awake!

ACTUALITY OF OPERATION

Norman Swan: The surgeon is using an electrode to stimulate parts of the brain to ensure he avoids as many vital areas as possible before starting the operation proper.

But there are researchers who feel that this way of identifying critical areas of the brain prior to surgery should be a thing of the past. And one technique which might replace it is called magnetoencephalography, where the magnetic waves from the electrical activity of the brain are measured.

But as you'll hear from one of the experts in this field, Professor Graham Harding, MEG or Meg goes much further than brain surgery, perhaps as far as our thoughts.

Graham Harding: Basically what you do is you use a device called a 'squid', which is a super quantum interference device, which allows you to measure tiny magnetic currents which are being generated from the brain.

Now, the advantage of these is that magnetic currents pass through the skull and the scalp without any smearing, whereas electrical potentials get smeared.

Norman Swan: By 'smearing' you just mean that they are not as clean as they could be.

Graham Harding: They're not as clean, and they get broadened. So that it's more difficult to locate where the signal is coming from. So the most common technique that people come across, which is EEGs, is great for actually measuring that discharges have occurred...

Norman Swan: This is the electroencephalogram that's done particularly when you've got epilepsy.

Graham Harding: That's right. But you can't tell exactly where it's coming from, because it's been smeared by the scalp and the skull.

Norman Swan: It's a bit like squinting at a light. You're seeing the light less clearly than you would otherwise.

Graham Harding: That's right. You're seeing it through a frosted window, basically. With MEG, or magnetoencephalography, it passes straight through the skull and scalp with no smearing, so therefore we can actually locate the point in the brain that it's coming from. And we can locate that very accurately within about 1.5 millimetres.

Norman Swan: So you can point to the bit of the brain that operates the thumb or indeed where the thumb feels things.

Graham Harding: That's right. You can use this technique, which is completely non-invasive - you don't even have to put electrodes on the scalp or anything. You just put this recording device very close to the surface of the scalp.

Norman Swan: Just like a scanner?

Graham Harding: Just like a scanner.

Norman Swan: Now we've just spent a fortune in Australia putting in one or two PET scanners, which is a radioactive scan which lights up parts of the brain which are in action at the time. Are you saying that this supersedes PET scanning?

Graham Harding: I think PET scanning is superseded anyway. The other techniques are slow. Their time window is always around the period of a second or more.

Our techniques will give us information millisecond by millisecond. So you can have a thousand pictures in a second. So that not only can you tell what areas of the brain are activated, you can tell the sequence in which they're activated.

Norman Swan: Let's go back to the beginning of this, which was talking about the thought. Because when it was originally mooted, it was said that this technique can actually measure a thought. You think a happy thought and we can find out where happiness is in the brain. Are we anywhere near that?

Graham Harding: Oh yeah, we're getting closer. We've been studying the visual cortex, where we see the pictures that our eyes receive. And we can now tell which part of the brain deals with colour, which part of the brain deals with motion. So we're approaching the stage now where we can see how the brain breaks down complex stimuli, and then how the brain puts it back together.

Norman Swan: But you're a long way from finding out where hating the government resides in the brain?

Graham Harding: We are a long way from that. In the end, I do not believe there will be a concept of mind. I think it will be a concept of brain function. But it probably won't be in my lifetime that we actually design the experiments which will allow us to do that.

Norman Swan: And finally, what about imposing magnetic waves back into the brain and actually changing brain function that way?

Graham Harding: That obviously is one of the ultimate Holy Grails, because that way you could overcome various peripheral defects. You could actually start, as you know, producing artificial pictures on the brain via a television camera system.

At the moment it is still very crude. We know we can actually use magnetic stimulation of the brain to produce particular behavioural patterns. So you can actually block things, you can block part of vision by putting a magnetic stimulator close to the surface of the head and just stimulating that area of the brain, and block part of the visual picture. But this is still a very crude technique. And it's a long way from the point where we can stimulate very small areas of the brain and get pictures as accurate as it can produce itself.

Norman Swan: The how-to-vote control?

Graham Harding: Yes, I don't think we should get to the how-to-vote control.

Norman Swan: So you don't need to get too paranoid just yet. Graham Harding is Professor of Clinical Neurophysiology at Aston University in Birmingham.

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The Health Report is broadcast at 8.30am and repeated at 8.00pm every Monday on Radio National, the Australian Broadcasting Corporation's national radio network of ideas.