fMRI—Telescope for the Brain

MRI (Magnetic Resonance Imaging) has taken great leaps forward in the past few years. Today it has expanded into fMRI (functional Magnetic Resonance Imaging) which maps brain activity. It is a technique for determining which parts of the brain are activated by different physical sensations or activities. According to this brief tutorial A subject is placed inside the MRI and a high resolution scan is taken of him. The subject is given stimulation (ex. shown images) followed by a low resolution scan. By comparing low resolution scans both with and without the stimulation, the fMRI can detect brain activity. fMRI can also correct for head movements and other distortions of the image. The low resolution images are then overlaid on the high resolution image to create a final picture.

fMRI measures the blood flow changes that occur in the brain based on stimulated activity. At the atomic level, hydrogen atoms in the blood are magnetic dipoles and react when in the presence of a magnetic field such as that used in an MRI machine. fMRI has the advantage of making non-invasive measurements in a relatively short amount of time which makes for a better procedure compared to most electrophysiological data acquisition systems which require the use of electrodes, wires, and more.

Each part of the brain controls a specific function. Here’s an example of site locations for sensory, motor, language, and vision.

In this Wired article Columbia University researchers use fMRI to map brain activity in an effort to detect when someone is lying. The activity in the caudrate region of the brain which controls emotion becomes engage when a subject is lying, but remains neutral when a subject is telling the truth.

In another application University of Michigan and Harvard researchers used fMRI to map how the brain perceives brands and products. This seems like an odd application, but it’s within the realms of technology.

Researchers are also using it to diagnose and treat bipolar disorder.

The technology of magnetic resonance imaging can be used in several forms. Wikipedia also related MRI technologies. Contrast MR uses a contrast agent such as iron oxide which causes a change in the magnetic field. This technique can be used to measure properties of the blood. Another is magnetic resonance spectroscopic imaging which uses a nuclear magnetic resonance technique to measure the magnetic properties of the nucleus of an atom. Different chemicals have different magnetic resonances.

One can build or supplement a magnetic resonance system with virtual instrumentation. Researchers at Battelle Memorial Institute, built their own magnetic resonance microscope that combines a confocal microscope with an MRI system to allow the study of living cells from two points of view simultaneously. The confocal microscope provides a 3-D image of the structure of the cell, while the MRI provides the magnetic imaging. Combining both images yields new information about the cell.

Best regards,
Hall T.