Eric Appelt
University School of Nashville
Precalculus and AP Physics C

Dr. Victoria Morgan at the VU Institute of Imaging Science

Dr. Morgan is working on a technique to use functional MRI mapping to help physicians determine the possible source location within the brain causing an individual to experience seizures. A seizure may be produced by a localized group of neurons intensely firing for a brief period of time, which may then cause the rest of the neurons in the brain to also fire producing a seizure. The seizure producing area will typically also experience brief periods of intense firing that do not result in a seizure, called interictal spikes.

When an area of the brain undergoes more intense activity, it will signal to the circulatory system the need for additional oxygenated blood. An MRI can actually measure a difference in tissue contrast when more oxygenated blood arrives in an area. A functional MRI has a patient perform an activity along a specific timecourse which is then recorded. Successive images of the brain are compared statistically to determine which areas had a heightened level of oxygenated blood when the activity is being performed. One could theoretically use this method to determine where interictal spikes occur in the brain, however, one does not know when the spikes were produced.

One method to generate a timecourse to determine when the spikes occur is to hook the patient to an EEG which can determine exactly when a significant spike in activity occurs, and using this data to help analyze the MRI images. This is difficult as normal EEG equipment is not safe to use near the strong magnetic field of an MRI scanner and specialized equipment must be used instead. Dr. Morgan has developed a statistical technique called two dimensional temporal cluster analysis to try and determine when interictal spikes occur by only looking at the images produced by the MRI.