fMRI Gets Improved: New Ways to fMRI

The improvements and innovations are coming fast and furious now. It is a great time to be into this stuff.

Traditional fMRI (it is strange to type that) detected blood flow. Hemoglobin in blood contains iron, which mediates changes in magnetic fields. These are, in turn, detected and converted to three-dimensional image data by the MRI. That same iron-containing molecule carries oxygen to the cells of the body. When neurons become more active they require more oxygen-carrying blood. Arteries in the vicinity of the active neuron cells respond by dilating in order to increase the supply. It is this extra blood that is detected by fMRI (traditional fMRI, that is).

This has been a boon to understanding the topographical correlates of thought and brain function. That's the upside. The downside is that it produces very course correlates. That is, it only measures increased blood flow in the vicinity of neural activity. It doesn't pin-point the actual activity topographically.

It is also contextually course information. In other words, it displays all activity, and can't discern between, say long-, and short-term PTP, or any of the staggering number of other protein interactions that are involved in different types of mental activity. These different types of activity are often as important as locational activity.

Finally, it has a course temporal aperture as well. Because it measures blood-flow, it tends to see the activity many milliseconds, or even seconds after the activity has started

Some of the timing and delay deficiencies have been overcome by coupling it with EEG scans as well. EEG scans have almost no positional information, just giving general areas of the brain where electrical activity is sourced, but it does give immediate feedback, which can then be narrowed by the fMRI imaging that comes in some time later.

Now, the researchers at MIT have begun to work on new ways for the fMRI to image actual protein/neurotransmitter mediated activity in the brain. Instead of simply measuring the amount of activity through increased hemoglobin in the area, these will image on the actual molecules involved in brain functions. They are accomplishing this by coming up with contrast agents (things that make an MRI image brighter or darker), which bind directly to the various molecular sites and chemicals in the brain used in brain and neuron function.

The upshot? Faster, more tightly synchronized time windows, more fine-grained spacial resolutions and magnification scales, and a whole new dimension of functionality. The functionality is based on being able to contrast specific molecular mechanisms having to do with specific types of brain activity.