Watching biology in action: The advent of new brain and molecular imaging techniques

By STEPHANIE GALL ’14

Staff Columnist

Two novel imaging techniques developed at MIT and Harvard University have opened a window into how the brain and cells function. These advancements have the potential to better our understanding of general brain and cell mechanisms as well as the processes involved in disease.

The MIT research team’s new brain imaging technique combines two well-known imaging methods: functional magnetic resonance imaging (fMRI) and magnetoencephalography (MEG). The former method detects changes in blood flow in the brain in order to determine what brain regions are active when an individual carries out a specific task. Regions with increased blood flow indicate areas in need of more oxygen, which represent the areas actively involved in carrying out the task. While fMRI can detect specific brain regions with accuracy, it is less adept at detecting when the observed brain activity takes place. MEG, on the other hand, which uses magnetic fields, can record when brain activity occurs within milliseconds. However, MEG cannot tell exactly from where in the brain the heightened activity came.

By combining fMRI and MEG, the researchers’ imaging method can record both the location and timing of activation in the human brain. Aude Oliva, of MIT’s Computer Science and Artificial Intelligence Laboratory, told the MIT News Office, “This method gives you a visualization of ‘when’ and ‘where’ at the same time. It’s a window into processes happening at the millisecond and millimeter scale.”

The researchers used the technology to observe how the brain processes visual stimuli such as animals, plants, faces and other objects. A mere 50 milliseconds after subjects viewed an image, the information was relayed to the primary visual cortex, located in the occipital lobe near the back of the brain. Within 120 milliseconds, subjects were able to identify the object. In the future, the researchers believe that scientists could use this method to study other sensory pathways or diseases that affect the brain.

Moving beyond brain regions and into the cell, Harvard scientists have developed a means of visualizing multiple biomolecules at once. This is a vast improvement over the previous imaging technique that only allowed researchers to see a few molecules at a time. Peng Yin, part of the Harvard research team at the Wyss Institute for Biologically Inspired Engineering, spearheaded the effort. As Yin told the Harvard Gazette, “If you can see only a few things at a time, you are missing the big picture.”

The new technique, dubbed Exchange-PAINT, is an updated version of DNA-PAINT, an imaging technique that Ralf Jungmann, one of the team members, developed as a graduate student. The researchers used DNA tags to bind a fluorescent tag to a strand of DNA. DNA is composed of two complementary strands, and when the two strands pair, the fluorescent tag lights up. Once lit, the light blinks, and the researchers can control the speed of the blinking. They can then take pictures of the molecules. This process allows researchers to visualize multiple, distinct biomolecules by using different colored fluorescent labels.

Donald Ingber, the director of the Wyss Institute at Harvard, is eager to see how the technique will be used in future studies. “Peng’s exciting new imaging work gives biologists an important new tool to understand how multiple cellular components work together in complex pathways,” Ingber said in the Harvard Gazette. “I expect insights from those experiments to lead to new ways to diagnose and monitor disease.” The ability to capture multiple cell components at once will greatly aid scientists’ ability to explore normal and abnormal complex cellular pathways.

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