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Colorful Brains: The Dancing Colors of fMRI

By Suraj Sheth

The introductory sequence of the popular show “Limitless” shows portions of the brain lighting up in brilliant colors as new connections are made. While the show may be based on a claim that has been disproved (that we only use 10% of our brains at any moment) its introductory sequence is somewhat similar to the ways neuroscientists visualize the brain. With new technologies, neuroscientists, now more than ever, are gaining insights into how the brain processes information in real time, furthering our knowledge of the way this approximately 3-pound organ functions.

One major tool that has revolutionized neuroimaging is functional magnetic resonance Imaging, or fMRI. fMRI is a procedure that uses an MRI machine to detect the differences in oxygenated and deoxygenated blood flowing in the brain, and is used to track changes in blood flow to different regions. Based on the idea that increased blood flow indicates that a certain region of the brain is active, scientists can use fMRI to see how the brain responds to various stimuli, and what regions of the brain are activated to in response to different kinds of information. fMRI is relatively easy to use and is very safe, and its results are applicable to a variety of different studies.

Students in the Neuroscience Seminar at Loyola University Chicago got to hear about one such study on Aril 19^th, 2016, from Dr. Michael Cohen. Dr. Cohen is a post-doctoral fellow in the Reber Laboratory in the Department of Psychology at Northwestern University, where, using fMRI, he studies the effects of aging on how people encode their memories, especially memories of value. He explained how he found that there were differences in how younger people and older people (60 years or older) achieve “value directed memory selectivity,” during verbal learning. Essentially, the way the brain stores memories that are deemed to be “valuable” changes as we age, at least for verbal learning. Dr. Cohen and his colleagues found that when both younger and older people were exposed to a set of words they had to learn, with some words having higher importance than others (indicated to the subjects with a value cue), both age groups used a region of the brain referred to as the “semantic network.” However, only younger individuals showed a significant increase in activity in their semantic networks when they were presented with “high value words.” Older individuals, on the other hand, had only small changes with “high value words,” but responded to “low value words” by having lower activity in their semantic networks. This means each group had a slightly different way of identifying, prioritizing, and learning high value words over low value words. The study also found that only younger individuals had “value-related increases” in activity in their semantic and reward processing networks in response to the “value cue.” (an increase in activation based on the cue’s value, and not the word itself). Interestingly, this increase in activity did not predict any difference in memory selectivity between older individuals and younger individuals. Dr. Cohen’s study shows how the processing mechanisms used by the brain to interpret information changes over our lifetimes, and how different age groups may engage their brains in different ways in response to the same stimuli.

fMRI studies can also be used to discover functional regions of the brain that previously had only been described in theory. This was the case for Dr. Norman- Haignere and other researchers at MIT, when they discovered a small region of the auditory cortex that was specialized for listening to music. This is the subject of the New York Times article “New Ways into the Brain’s ‘Music Room’”. The article describes how Dr. Norman- Haignere and his team developed a mathematical model to determine which neurons in the brain’s auditory cortex have similar activation patterns in response to various stimuli. They developed this model by first exposing human subjects to a wide range of everyday sounds, from cars starting and planes taking off to people speaking in different languages. They then analyzed the voxels (which are 3D pixels) of the fMRI data to determine the generalized patterns by which the brain analyzes incoming auditory information. After coming up with 6 general patterns, they matched each pattern to the kinds of noises that activated them, and they found that one of the pathways was activated exclusively by music (sounds that had rhythmic and/or melodic qualities). This may indicate that there was some evolutionarily beneficial purpose to music in humans. The study is also a good stepping stone to future studies that explore differences in musicality between musicians and non-musicians, and whether musicality changes with age.

Both Dr. Cohen and Dr. Norman- Haignere were able to use fMRI technologies to discover how the brain processes information. Dr. Cohen’s study was comparative, seeing which functional changes occur as we age. Dr. Norman- Haignere utilized fMRI to discover the existence of a new network within the brain, one that has evolved specifically for the interpretation of music. Both studies are interdisciplinary, integrating psychology and computational neuroscience to figure out the function and importance of different areas of the brain. The fact that both studies are highly relevant is a testament to the flexibility of fMRI studies. Through technologies like fMRI, we can gain insight into the essential internal processes that make us who we are today.

Sources:

Articles:

http://www.nytimes.com/2016/02/09/science/new-ways-into-the-brains-music-room.html

http://www.nytimes.com/2016/02/09/science/lending-her-ears-to-an-mit-experiment.html

Dr. Cohen’s Original Study:

Cohen, M.S., Rissman, J., Suthana, N.A., Castel, A.D., Knowlton, B.J. (2016). Effects of aging on value-directed modulation of semantic network activity during verbal learning. NeuroImage, 125, 1046-1062

Images:

http://news.stanford.edu/news/2013/march/images/neuroimage_news.jpg

http://www.billboard.com/files/styles/article_main_image/public/media/music-brain-2016-billboard-650.jpg