iMindFuck

Nowadays there is a popular application called fMRI (where the f stands for functional), used to identify which part of the brain is working when any type of activity is taken place. The principle is simple. When a part of the brain becomes active, blood flow increases into that part of the brain and that is detected in an MRI scan as a change in contrast on the image.

The image above is the result of the next experiment: 

A subject was told to move their left hand for ten seconds and then not to move for others ten seconds and so on. An image of the brain was acquired every second of the experiment. 

If you are moving your left hand during a fMRI; at the end of the experiment, the analysis of the data will show that the right motor cortex of your brain will be illuminated as active, and this is because when you are moving your left hand, the blood flow is increased in that part of the brain, and that small changes in blood flow are detected by MRI as a change in contrast of the different images. What happens in the background is that the scans acquired are then analyzed in search for small changes in every image, and where small changes are detected consistently, that means there is activity.

At the bottom of the image, there is a green graph tracing the activity of a selected area of the brain during the whole experiment. You can see the selected area on the brain of the middle in the second row. This graph is going up, and going down. When it goes up means activity, and “no activity” when it goes down.

One clinical application of fMRI is the detection of active areas of the brain, before a neurosurgical intervention where brain tissue needs to be removed. In that way, when a tumor needs to be removed, it can be removed as extensively as possible, while preserving the active adjacent areas.