Functional magnetic resonance imaging (fMRI) provides a means to visualize brain activity, but it does not measure the activity of brain cells per se. Instead, blood flow within the brain is used to make inferences about neural activity - without really knowing the precise relationship between the two processes.
Patrick Drew, Ph.D., is studying that issue as a new assistant professor in the Engineering Science and Mechanics department and the Neurosurgery department at Penn State University. A better understanding of the basis of fMRI signals will help researchers and clinicians extract more information from fMRI, and may lead to improvements in the technology, he says. His appointment at Penn State was supported by an NINDS grant made possible through the American Recovery and Reinvestment Act (ARRA).
Dr. Drew joined Penn State in June 2010, after completing a postdoctoral fellowship with physicist David Kleinfeld, Ph.D., at the University of California, San Diego. In Dr. Kleinfeld’s lab, he used electrophysiology and two-photon microscopy to correlate neural activity and blood flow within the brains of awake mice. Two-photon microscopy uses a thin laser beam of light to generate images at high speed and with high enough resolution to visualize blood flow within individual capillaries. Dr. Drew will continue and extend this research at Penn State, where a strong emphasis on materials science fits well with his interests, he says.
"There is a push [at Penn State] to study the brain as a material. Even though brain circuitry is a fascinating and important topic, there is more to the brain than the connections between neurons. The blood vessels that supply oxygen and nutrients to neurons are important and often overlooked," he says.
Part of Dr. Drew's research will focus on deciphering the communication that occurs between neurons and blood vessels. In order to meet their demands for energy, neurons release chemicals that tell blood vessels to increase or decrease the delivery of blood, but the details of this communication are unclear.
"We want to understand the messages neurons send to the vasculature, and determine how neural activity is reflected in changes in blood flow," he says. In addition to helping understand fMRI signals, this research is relevant to developing better treatments for stroke, which is caused by an interruption of blood flow in the brain. Tapping into cerebral blood flow regulation could help restore normal blood flow after a stroke and improve recovery.
Last updated March 20, 2013