Washington Week: Student Voices (O)

MRI, fMRI give insight into the brain's function
By Violet Salazar
The California Aggie (UC-Davis)
11/21/2007

(U-WIRE) DAVIS, Calif. — The researchers at the University of California at Davis Center for Mind and Brain are not psychics, but they can read your mind. Literally.

From the time the CMB was founded in 2002, scientists have been trying to gain a better understanding of the inner workings of the human brain.

With the help of neuroimaging technology, such as magnetic resonance imaging and functional magnetic resonance imaging, scientists at the CMB have been able to get a first-hand look at the human brain and are able to apply what they see to a wide spectrum of studies.

The only difference between MRI and fMRI is that fMRI has different settings. MRI gives you an overall image, while fMRI gives you a picture in more detail, which helps you identify what parts of the brain are active.

The goal of the center is to address the "fundamental question: 'How does the mind arise from the biology of the brain?'" according to the facility's website. The CMB approaches the question from many areas of interest.

The center studies various areas of psychology including attention awareness, cognitive control, language, memory, multisensory integration, music cognition, social cognition, and visual cognition from cognitive neuroscience and developmental perspectives.

Assistant professor of psychology David Whitney uses MRI and fMRI in his research of perception, vision action and visuomotor localization.

"We know what the equation is, we know what the brain is doing," said Whitney, "but we use the MRI to see where in the brain it's happening, which brain region is working."

In many of the studies done in Whitney's lab, the MRI and fMRI are used to identify parts of the brain that are involved in perception and localization in order to understand "what allows humans to perceive and interact with objects," according to the CMB website.

"We compare brain activity with some record of what the subject is doing at the time," said Santani Teng, sophomore psychology graduate student in Whitney's lab.

Using this data, scientists can develop a "brain map," a result commonly seen in experiments dealing with this type of neuroimaging.

One such study was done to investigate auditory localization. The images obtained helped to explain what regions of the brain differentiate where certain sounds are perceived. Each experiment done in the lab requires several subjects to be scanned, resulting in thousands of images that need to be analyzed and summarized.

"When you see those activation maps," Teng said, "what you see ... it's like an overlay [of all the MRI and fMRI scans]," Teng said.

The two MRI systems used by the center are the 1.5T and the 3T. The neuroimaging machines used by scientists at the CMB are located in the Imaging Research Center located in the UCD Medical Center.

While Whitney's lab tries to discover the origins of perception, David Corina has been using neuroimaging to explore a very different interest.

Corina, a professor of linguistics and psychology who has been with the CMB for two years, studies language and how language is processed. Currently, Corina and his lab team are working on a study designed to illustrate the differences of processing gestures or sign language.

Junior specialist Mary Catherine Mendoza said the current experiment in the Corina lab involves a subject identifying images. While in an MRI machine, subjects are shown flashes of images of a person signing a word in sign language are then asked to determine whether an image was a possible or impossible sign.

"We will use that information to build a foundation (for the rest of the study)," Mendoza said.

While both Corina and Whitney integrate neuroimaging in their research, they both agree that it is a tool that is only used when proper background research is done. Both doctors say that behavioral studies are the basis of a good neuroimaging experiment.

"The best fMRI experiment is also one that can show behavior," said Corina. "[MRI] is not a tool if you want to fish for an experiment to see what lights up."

Even though Teng admits that he often hears researchers say, "Let's throw it in the scanner and see what happens," he said because the tool yields so many different images, it is better to have a background of the subject being studied.

"It gives you an opportunity for greater understanding," he said.

Using MRI and fMRI does have its limitations, Whitney said. "fMRI is only good for certain types of questions."

When it comes to seeing how fast a process works or the exact moment something is perceived, fMRI is too slow to give any accurate information. However, if a researcher is studying where a process occurs, as is the case in Whitney's visuomotor studies, "fMRI is perfect for that," he said.

In the end, Corina said that fMRI has more pros than cons.

"The best science is done when it's very theory driven," he said. "This can be used as a tool to validate those models."

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