Scientists Construct First Detailed Map of How the Brain Organizes Everything We See

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Our eyes may be our window to the world, but how do we make sense of the thousands of images that flood our retinas each day? Scientists at the University of California, Berkeley, have found that the brain is wired to put in order all the categories of objects and actions that we see. They have created the first interactive map of how the brain organizes these groupings.

The result — achieved through computational models of brain imaging data collected while the subjects watched hours of movie clips — is what researchers call “a continuous semantic space.”

“Our methods open a door that will quickly lead to a more complete and detailed understanding of how the brain is organized. Already, our online brain viewer appears to provide the most detailed look ever at the visual function and organization of a single human brain,” said Alexander Huth, a doctoral student in neuroscience at UC Berkeley and lead author of the study published Dec. 19 in the journal Neuron.

A clearer understanding of how the brain organizes visual input can help with the medical diagnosis and treatment of brain disorders. These findings may also be used to create brain-machine interfaces, particularly for facial and other image recognition systems. Among other things, they could improve a grocery store self-checkout system’s ability to recognize different kinds of merchandise.

“Our discovery suggests that brain scans could soon be used to label an image that someone is seeing, and may also help teach computers how to better recognize images,” said Huth.

It has long been thought that each category of object or action humans see — people, animals, vehicles, household appliances and movements — is represented in a separate region of the visual cortex. In this latest study, UC Berkeley researchers found that these categories are actually represented in highly organized, overlapping maps that cover as much as 20 percent of the brain, including the somatosensory and frontal cortices.

To conduct the experiment, the brain activity of five researchers was recorded via functional Magnetic Resonance Imaging (fMRI) as they each watched two hours of movie clips. The brain scans simultaneously measured blood flow in thousands of locations across the brain.

Researchers then used regularized linear regression analysis, which finds correlations in data, to build a model showing how each of the roughly 30,000 locations in the cortex responded to each of the 1,700 categories of objects and actions seen in the movie clips. Next, they used principal components analysis, a statistical method that can summarize large data sets, to find the “semantic space” that was common to all the study subjects.

The results are presented in multicolored, multidimensional maps showing the more than 1,700 visual categories and their relationships to one another. Categories that activate the same brain areas have similar colors. For example, humans are green, animals are yellow, vehicles are pink and violet and buildings are blue.

“Using the semantic space as a visualization tool, we immediately saw that categories are represented in these incredibly intricate maps that cover much more of the brain than we expected,” Huth said.

Other co-authors of the study are UC Berkeley neuroscientists Shinji Nishimoto, An T. Vu and Jack Gallant.

Journal Reference:

1.Alexander G. Huth, Shinji Nishimoto, An T. Vu, Jack L. Gallant. A Continuous Semantic Space Describes the Representation of Thousands of Object and Action Categories across the Human Brain. Neuron, 2012; 76 (6): 1210 DOI: 10.1016/j.neuron.2012.10.014

http://www.sciencedaily.com/releases/2012/12/121219142257.htm

A Peek Inside Rappers’ Brains Shows Roots Of Improvisation

 The warmer orange colors show parts of the brain most active during improvisational rap. The blue regions are most active when rappers performed a memorized piece.

Some rappers have an impressive ability to make up lyrics on the fly, in a style known as freestyle rap.

These performers have a lot in common with jazz musicians, it turns out.

Scientists have found artists in both genres are using their brains in similar ways when they improvise.

A group of jazz pianists had their heads examined in a 2008 PLOS One study, which subjected the musicians to functional magnetic resonance imaging scans. These scans highlight areas of brain activity.

When riffing on a tune instead of playing a memorized composition, the musicians had lower activity in a part of the frontal brain that is thought to be responsible for planning and greater activity in another part of the frontal brain believed to motivate thought and action.

After hearing about the jazz study, Los Angeles rappers Michael Eagle and Daniel Rizik-Baer contacted one of the researchers, Allen Braun, chief of the voice, speech and language branch of the National Institute on Deafness and Other Communication Disorders. Eagle and Rizik-Baer proposed a similar study on freestyle rap.

Soon Braun’s colleague Siyuan Liu at NIDCD put together a team, which included the two rappers, to determine what was happening inside these performers’ brains.

In their study, published today in Scientific Reports, five professional rappers were given a set of lyrics to memorize. A week later each was put inside an MRI machine to put on his performance.

“It’s not a very natural environment, that’s for sure,” notes Braun, a co-author on the latest study. “It’s noisy and you have to lie on your back. And you need to stay still.”

The clinical setting may not have been the normal setting for the rappers, but they had little difficulty performing on cue. Each would perform the preset rap, and then they would switch to improvising to the same music track.

“By comparing the two, we could see the neural activity associated with freestyle rap,” Braun says.

When Liu and the other researchers examined the fMRI data, they found that, like the jazz musicians, the rappers’ brains were paying less conscious attention to what was going on but had strong action in the area that motivates action and thought.

“Unlike the jazz study, these changes were very strongly associated with the left hemisphere of the brain,” Braun says. That’s the half of the brain where, for most right-handed people, language is processed.

The team also found a network of connections in the performers’ brains during the freestyle raps, linking parts of the brain responsible for motivation, language, action and emotion.

And raps that were rated as more innovative correlated with more activity in the region of the brain that stores words. It’s not surprising, says Braun, “that the more creative the rap, the more they’re tapping the lexicon.”

The study is part of a larger body of research that is hoping to determine what is happening inside the brain during the creative process. Braun says that he’d like to know more about what happens in the next phase of creativity, revision. He has recruited a group of poets for that study.

http://www.npr.org/blogs/health/2012/11/14/165145967/a-peek-inside-rappers-brains-shows-roots-of-improvisation?sc=emaf

Thanks to Dr. Nakamura for bringing this to the attention of the It’s Interesting community.