Ok, we have two main ways of looking at the brain.
One is magnetic resonance imaging, or MRI, and another is magnetoencephalography, or
MEG.
In the first case, MRI allows us to look at the structure of the brain so we can measure
how different tissue types in the brain are effected as we get older.
We can also measure function of the brain during simple tasks.
This is functional MRI.
So we can see how blood flow changes in response to a particular task change as we get older.
The other technique of MEG, magnetoencephalography, also allows us to look at the activity in
the brain but at a much faster timescale.
So we can trace our brain rhythms that occur several hundred cycles per second.
So next I am going to put on these glasses.
These are basically just going to give a kind of starting point for when I digitalise your
head shape.
So if I start putting these on and then if you want to hold them to your face and just
put them so they are comfortable and then I will just tighten them up.
Is that ok?
Yeah.
They might be a little bit loose.
The main advantage of MEG is that we can look at communication between brain regions and
that is vital for all these cognitive functions like memory, language, emotion, because if
our communication between brain areas is slightly delayed, or made more variable, then our cognitive
functions will suffer.
So the next thing I am going to do is digitise your head shape.
Basically going to be using this electronic pen on various points on your head.
So you are going to see your head shape appear on this screen there and it's basically going
to tell the MEG what your head shape is.
And when you come back for your MRI scan we can overlay the two lots of images, so we
can look at where all the activity is coming from and kind of superimpose it on your MRI
scan.
So it is really important for this bit once I start that you stay as still as you can.
And I just need to go down your nose and across your cheeks.
Excellent, good job at keeping still.
You can relax now.
So one of the tasks that we do is a very simple task that involves pressing keys whenever
you see a flash and hear a sound.
And this activates the primary sensory regions and the visual cortex, the auditory cortex
and the primary motor regions in the motor cortex.
And we know as people get older the activity as measured by fMRI in these regions tends
to decrease.
But what we are not sure about is whether that is a consequence of changes in the blood
supply to the brain as we get older or actually changes in true neuro activity.
And this is what the MEG scan can tell us.
It can separate out what's a true change in your activity as you get older, in response
to this simple reflex task, and what's the change in the brain's plumbing if you like.
So the combination of MEG and fMRI is very helpful to separate out the neuro contribution
from what we call the vascular contribution, or the contribution of the brain's blood supply.
That's the way it looks.
Wavy wavy lines.
This just gives you electrical activity somewhere in the element with only after extensive data
analysis.
That is why we do the MRI scan as well.