fMRI: A Window to the Workings
of the Brain
Stephen Rao, PhD
Medical College of Wisconsin Neuropsychologist
Director of Functional Imaging Research Center
“This is really an exciting time in fMRI research and Froedtert & Medical College is right at the center of it.”
Functional Magnetic Resonance Imaging (or fMRI) is an integral part of nearly all aspects of the neurosciences and Froedtert & Medical College is a leader in both development of and innovative uses for this state-of-the-science technology. Stephen Rao, PhD, internationally known for his research in the area of functional imaging, gives specific insight on the promise of fMRI.
Q: What exactly is fMRI and how does it work?
Functional Magnetic Resonance Imaging was developed in the early 1990’s and Froedtert & Medical College really played a pioneering role in that development. fMRI is a technique that takes highly detailed pictures of the brain very quickly — by that I mean we can “see” the whole brain every couple of seconds. That gives us information about the brain over time, not just space.
What this allows us to do is to identify areas of the brain that become neurally active in response to different activation tasks. We’ve developed techniques that allow us to present a patient with stimuli while they are in the scanner. For example, we can give a task that will activate, say, a person’s memory, while the image of their brain is being generated. That gives us a detailed picture of the exact brain location for memory.
When an area of the brain becomes neurally active, there is an increase in blood flow to that region — actually more blood than is really needed, so that there is a “pooling” of oxygenated blood. This pool of oxygenated blood has magnetic properties, so it is easily visible on the picture that the fMRI scanner generates.
Q: How does this compare with what was used previously for producing images of the brain?
Prior to fMRI, we mapped the brain using a procedure called Positron Emission Tomography, or PET. This technique is invasive because you need to inject the patient with a contrasting agent. fMRI is totally non-invasive. Since we are picking up on a natural contrasting agent — oxygenated blood — there’s no need to inject a patient to see the stimuli.
In addition, PET does not allow for tracking of a stimulus over time. You can measure the results of a patient doing an activity for a 40-second period with PET, but with fMRI we can scan the brain for up to an hour and see second-by-second the changes that occur in the brain in response to different aspects of the task.
Q: It sounds as if there are a variety of uses and applications for fMRI. Can you tell us about the role fMRI is playing?
Initially, fMRI was and continues to be used to map the regions of the brain that are responsible for different types of functions, like memory, attention, and the visual process, to name a few. That has helped us make fantastic strides in epilepsy surgery because this map allows surgeons to pinpoint the functional areas of the brain, helping them to identify where seizures are originating.
fMRI is also going to play a significant part in the early detection of diseases like Multiple Sclerosis, Alzheimer’s and Huntington’s. The symptoms of these diseases make most methods of diagnosis difficult. For Alzheimer’s in particular we are looking at memory tests that will be given to patients in the scanner that will help us to separate normal memory loss due to aging from the beginnings of Alzheimer’s.
We’re also using fMRI to learn more about the recovery process from stroke. fMRI is even showing us exactly how specific drugs affect the brain, with some studies focusing on the cause of cravings for drugs such as nicotine and cocaine.
Q: What else does fMRI offer for the future?
In the next five years I see significant growth in our ability to take the information we’ve gathered from fMRI and make it available to other physicians for diagnosis and monitoring. We’re also enhancing fMRI itself. Recently, we developed a technique called “real time fMRI” that takes the images from the scanner and projects them on a monitor as they’re being collected, so we can analyze the data while it’s happening. This will be a great help in accuracy, because we’ll be able to correct any invalid data instead of bringing the patient back and repeating the test.
This is really an exciting time in fMRI research and Froedtert & Medical College is right at the center of it. Since our pioneering efforts at the beginning and our continued research leadership over the last 10 years, we’ve been able to attract even more funding for studies. In fact, 25 percent of the projects that are sponsored by the General Clinical Research Center (GCRC) are fMRI-related. We’re also working with fMRI manufacturers to make better scanners. And we’ve become well-known as the definitive site for fMRI training. Since 1997, we’ve trained over 450 scientists, physicians and researchers from 13 countries.
The bottom line is that all of this results in a higher level of care for a wide variety of neurology and neurosurgery patients.