Continuing advances in magnetic resonance imaging are allowing scientists to explore what philosophers could only speculate about for thousands of yearsâ_"the innermost workings of the human brain.
Duke brain MRI researchers are pioneering many of the ongoing developments in MRI technology, allowing the study of diverse phenomenaâ"such as language, emotion, schizophrenia and depressionâ"and shifting the field from solely an investigation of brain structure.
"[MRI] is a huge initiative being pushed by the Duke administration," said Allen Song, associate director of the Duke-UNC Brain Imaging and Analysis Center. "Duke is now at the forefront of this research."
One area where the Medical Center is gaining particular expertise is functional MRI, which can track blood flow within the brain and identify the areas being activated when patients perform certain tasks. Developed a decade ago, fMRI is continually being improved and applied to more areas.
"[Functional MRI] opens up a huge field for scientists interested in how the brain works... [as well as] the pathology of certain terrible diseases," Song said. "The importance of functional brain imaging is really beyond my imagination."
MRI in humans works by manipulating the properties of hydrogen, the atom that accounts for 63 percent of the body. Each hydrogen atom consists of an electron revolving around a single-proton nucleus. The large magnetic field focused by the MRI machine aligns the "spin" of every proton along one specific axis.
Radio waves are then applied, forcing the protons to wobble as if they were spinning like a top. When the radio waves are removed, the protons release a burst of energy picked up by surrounding detectors. The signals emitted vary for different types of human tissue or other materials, allowing for detailed internal scans of the human body.
The basic technique of MRI is consistent across the various improvements to the technology that Duke is developing.
The ever-shrinking scale that MRI is able to resolve is one major advance in the fieldâ_"and the smaller the anatomical detail, the greater the overall picture of brain function.
"We want to take it down to the micron level... and look at the microarchitecture of brain function," McCarthy said. "It's a quantitative change that will lead to a qualitative change in brain imaging."
Magnetic resonance microscopy--a variant of MRI--provides Allan Johnson, director of Duke's Center for In Vivo Microscopy, with the ability to look at mouse brains on the level of tens of microns. Although the technology is not applicable to humans, scientists can model various human diseases--including Alzheimer's Disease and depression--in mouse brains and gain precise pictures of how the disease operates.
"We can make accurate measures of different structures in the brain that are significant for that model," Johnson said.
Another MRI variant that Duke is pursuing is Lorentz imaging, which applies a strong magnetic field to produce a detectable force on electrical conductors, such as individual neurons in the brain. "[Lorentz imaging] holds promise of direct imaging of neuronal activity," said Song. Current MRI reliance on blood flow is only coarsely correlated to neuronal activity, he added.
Such precise identification of brain operations has long been thought to be useful in the development of better treatments for some diseases. "What part of the brain is active can tell you what the basic process [of a disease] is," said Cynthia Kuhn, professor of pharmacology and expert in neuropharmacology. "That may help you develop new therapies."
Johnson stressed that the ultimate benefits of MRI will inevitably grow out of the greater knowledge it produces.
"If you give basic scientists tools, they can usually do something very useful for the human condition," he said.
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