You all remember how I had an MRI administered by my friend Josh while I was in the States, right? Well, the last part of it was a diffusion scan. From the point of view of the patient, this is the most teeth-jarring four minutes of the procedure. The entire scanner bed vibrates. This shakes around the water in your head so that the position of the tissues in your brain can be determined. After some technical jiggery pokery, a map of the direction of connections between the tissues can be produced: a fiber trace image like the one above.
The difference between this and the first three images in the previous post is like the difference between a scalar (number) and a vector (number & direction). In the previous images, you can see where the structures in my brain are, like the cerebellum and the ventricles. In these images, you can see how they're connected: both where they are and the direction they're pointing.
The second set of three images show colour-coded structures in my brain much more clearly than the previous image, thanks also to the diffusion scan. The right and left hemispheres and cerebellum stand out distinctly.
I'm still not over the notion that all of this can be done. It's amazing, no?