TITLE: Magnetic Resonance Imaging of Human Brain Function

SPEAKER:

TIME: Thursday Nov. 4, 1999 at 4 PM

PLACE: George P. Williams, Jr. Lecture Hall, (Olin 101)

With recent development in ultra-fast imaging, magnetic resonance imaging (MRI) has evolved into a powerful tool for exploring the human brain function. Neuronal activity increases cerebral blood volume, cerebral blood flow, and oxygen delivery in small arteries supplying the activated cortex. Because oxygen delivery exceeds local demands, the capillary bed fills with larger amount of oxyhemoglobin than the cortex at rest. This increase in local concentration of diamagnetic oxyhemoglobin results in decreased local susceptibility effects and increased signal intensity on MR images by 1-5% relative to that at rest. This small increase is detectable in vivo on a pixel-by-pixel basis yielding maps of human cognitive functions. The fundamentals of functional MRI technique and its application in brain plasticity in stroke patients will be presented.