Time for the next installment in the tour through my brain. This time we have an image colelcted using a 'diffusion' technique. What this measures is where water moves during a short time delay. The molecules of water are always in motion, this is can be seen under a microscope as the Brownian motion effect. As the molecules move and bump into each other they follow a 'random walk' - at each collision their direction of travel changes. Overall they will make some gradual progress in one direction, even though the path they have taken is much longer.

If we consider at an instant a collection of water molecules that start in one place. Then look agagin a little time later, what we will see is that they will have spread out in all directions (having all taken complicated 'random walks' to get there). If we now do the same thing, but put the water in a narrow tube, the water molucules are forced to travel mainly along the tube. They will end up only moving in directions up or down the tube.

So what does this have to do with the brain? Well the white matter (see last blog entry) is made of lots of long 'tube-like' fibres. Water can travel along the fibres easily, but it is very hard for it to travel across the fibre wall. However, the grey matter allows water to travel more-or-less in all directions equally. Thus if we can measure where the water travels, or diffuses, we can distingish different bis of the brain.

The image above is what is called a 'Fractional Anisotropic' image. This is a fancy name for a measure between 0 and 1 of how much the diffusion of the water is constrained. So a value of 1 says it can only go one way - along a fibre, whereas 0 says it can go in any direction. So the image really clearly shows up the white matter in my brain.

You might be thinking (if you have ready my last post) that we already separated white and grey matter, so what more does this method tell us? Well diffusion provides more information than just this image. We can, for example, also look at how fast the water moves and so try to spot areas where the brain is damaged. We can also determine the direction the water moves and so work out which way the fibres are going. This last part (which is a bit harder to do) produces some really impressive images of how the brain is wired together. If I can work out how to do the calculations I will show you some of this another time.

A week or two ago I was looking at pictures of my brain. This week I have let my computer loose on them, the colourful images above are the result. What my computer has done is remove the skull and other non-brain bits then identify the different types of brain tissue it can see. This time we have a view from above and one from behind cutting through around where my ears are.

Last blog entry I pointed out that in the brain you can see white matter and grey matter. This time the computer has highlighted the different bits using different colours. So the gray matter is now in blue and the white matter in yellow. The green bits are the liquid (mainly water) that surrounds the brain.

You can see that there is lots of white matter - this is made up of lots of long fibers that connect different regions of the brain. The fibers are essentially long tails coming from brain cells and allow different bits of the brain to talk to one another. This is why we might think of it as the wiring of the brain.

We might say that the grey matter is where the work is done, as it is packed full of brain cells. You can see from the pictures that it occupies quite a thin layer and lots of the space is taken up by white matter. The grey matter is basically a sheet of cells approximately 5mm thick, but it is folded up so that you can get a lot in. The folding of the the grey matter is what gives the brain its distinct look, it also makes it relatively easy to get lots of white matter connections between all the different regions.

From my calculations I have roughly 0.8 liters of grey matter volume. Given my crude estimate of thickness above of 5 mm, that gives and area of 0.16 square metres (40 cm by 40 cm) all folded up inside my head. Whether that means I have lots of brain cells or not I don't know. I am sure it is not how much but how you use it that counts!

Last time I wrote I was talking about my experiences inside a Magnetic Resonance Imaging (MRI) scanner. This was all in aid of gettting various images of my brain as part of a research project (and not because there is anything wrong with it!)

Now I have been able to get hold of the those images and here is the first one. Isn't it amazing! Without having to take my head apart (something I am not willing to permit) and just by sticking me in big magnet (with various other electronics to hand) it is possible to get a really detailed image of the inside of my head. The resolution is impressive too - each cube that makes up the 3D 'picture' of my brain is just 1mm x 1mm x 1mm. That is about 4 million voxels (the 3D equivalent of pixels in 2D images) to represent my whole head.

I have just given you two slices of my head: one that looks down on me as if you had cut the top off at he level of my forehead. The right-hand picture is as if you were looking from the side and had cuy me in half just to the left of my nose.

So what can you see in these pictures? Well you can see the outline of my head and inside it is a brain (what a relief) and you should be able to sport it is made up of different parts. There is a 'hole' in the middle that is full of fluid, which is connected to the fluid that sits between the outside of the brain and the skull. The brain itself is mainly made of two types of tissue. In lighter grey in these pictures is 'white matter' - this stuff is basically the wiring for the brain so that messages can get from one part to another. The darker grey bits, mainly around the outside, is the 'grey matter' - the stuff that basically contains the brain cells that do all the work.

I am going to ahve a hunt around and see what else I can find out about my brain from the MRI images. Watch this space...

As a NOISEmaker you never know to whom you will be explaining your science next. In my most recent example it was to Ainsley Harriot and the audience of Ready Steady Cook (or it will be once the program gets on TV).

Both Vicki and myself were invited on the show, so that among all the craziness of cooking a meal in 20 minutes - a job thankfully mostly done by a professional chef - we could talk a bit about science. Like all the NOISE activities we were trying to show that scientists are quite normal people and that science can truly be interesting and not really difficult.

The star of the show (apart from Ainsley) was probably Vicki's experiment - a really neat trick to make marshmallows grow. Sadly the effect isn't permanent, so you cannot get more marshmallow for your money, but illustrates some really simple science, which an easily be done by anyone. Of course if you want to see how its done you will have to watch the show (or cheat and look here).

As for my experience: I had a fantastic time. James Tanner, my chef, produced an enormous quantity of food from very few ingredients almost instantaneously. I had no idea how quick 20 minutes could pass and no idea how James could do so much - even though I was stood right next to him, and not that I really contributed much help!If you have ever wondered: the chefs don't know what food they are getting before the show begins and they only have 20 minutes to cook in - which felt like 5 minutes to me, so must be even worse for them.

Was being on the show worth the effort? I hope so, it is great to think that we don't have to box science into particular 'science' TV shows, but that everyone can take an interest. Hopefully too we can illustrate that science at school can lead to some of the most interesting and varied career options going, or at the very worst it will get you cooking on TV.