Magnetic Resonance Imaging (MRI)
Magnetic Resonance Imaging (MRI) is a non-invasive technology used by researchers to study brain anatomy and function. MRI uses a strong magnetic field and radio waves to measure signals emitted by excited hydrogen atoms present in various types of bodily tissue. These signals are converted into images that show different degrees of contrast for different tissue types, which allows researchers to create detailed anatomical images of the brain. Functional MRI (or fMRI) uses MRI technology to measure brain activity, which can then be superimposed on images of brain anatomy from MRI. Unlike MRI, fMRI measures blood-oxygen-level dependent (BOLD) signals that indicate the amount of blood in different areas of the brain. Blood volume increases as a function of neural activity because the brain does not store the glucose needed to provide energy to the metabolically "expensive" activity of its neurons, and blood must be shunted to brain regions that are most active. Like EEG, fMRI measures the activity of large populations of neurons. However, the spatial resolution of fMRI is much greater than that of EEG-fMRI has fine spatial resolution but poor temporal resolution (unlike EEG). Researchers at the University of Nevada, Reno, are using fMRI to study a broad spectrum of cognitive and perceptual abilities including vision, memory, and uniquely human skills such as reading.