Prof. Hillman Awarded NIH Grant to Study the Resting Brain

3D in-vivo two photon microscopy of astrocytes (white) interacting with blood vessels (red) in the cortex.

Elizabeth M. C. Hillman, assistant professor of biomedical engineering, has just been awarded an NIH R01 grant for $1.7 million over five years to study the resting brain.

“We are very excited about this,” she said. “While most researchers have focused on what the brain does in response to a particular task, such tasks invoke relatively small changes in energy consumption compared to the amount of energy that the brain is using before you do the task.
So what else is the brain doing?”
Hillman, who directs the Laboratory for Functional Optical Imaging, specializes in using optical imaging and microscopy techniques to explore the way that the brain modulates blood flow to meet its energy demands. Unlike her earlier work however, she will now be studying the brain while it is “doing nothing.” She was inspired to study this area more closely because of recent findings in human functional magnetic resonance imaging (fMRI) that use a technique called functional connectivity mapping (FCM).
FCM was developed when researchers performing fMRI found that if they recorded images from people without asking them to perform a task at all, interesting fluctuations in brain blood flow could be observed. They further found that some of these blood flow changes were consistently synchronized across particular regions of the brain, and inferred via FCM that these regions might be functionally connected networks, essentially “talking” to each other at the neuronal level. “There is a romantic notion that these networks might even be related to higher processing and consciousness, particularly since they could be related to the brain’s massive background energy usage,” said Hillman. “The major excitement, though, stems from findings that suggest that these networks are disturbed in people suffering from conditions such as schizophrenia, autism, ADHD, traumatic brain injury, and many others.”
These neurological conditions have been very difficult to study and monitor until now, and as a result, FCM is rapidly being adopted by researchers to explore all manner of brain conditions. Hillman’s new project is focused on figuring out what the fluctuations in blood flow that are revealed by FCM actually mean. Her earlier work has focused on how blood flow is related to neuronal activity during stimulation, so, she said, “we will use all of our advanced in vivo optical imaging and microscopy methods to look at how everything works when the brain is at rest. We also plan to do some measurements that combine our optical imaging methods with fMRI.”
Hillman added that there is a lot of concern that we don’t understand enough about blood flow in the brain to interpret FCM results with so much certainty. She and her team hope to lay this uncertainty to rest.
“We might also find a lot of other interesting things, such as some other meaning for the networks that have been found, and the difference that people see in different pathologies,” said Hillman. “For example, if we find that some of these fluctuations represent changes in blood vessels independent of neuronal activity, this could mean that some of the conditions being studied using FCM actually have vascular manifestations, which would be a very important result for the development of new diagnostics or treatments for these disorders.”


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