Researchers have used brain scans to measure how the brain "sees" pictures—and to try to predict what a person is looking at.
Winning at "I spy" would be a whole lot easier if there were just some way to know what your opponent was looking at. It's not too far-fetched an idea. A team of researchers in California has developed a way to predict what kinds of objects people are looking at by scanning what's happening in their brains.
When you look at something, whether it's a tomato or your backpack or your best friend, your eyes send a signal about that object to your brain. Different regions of the brain process the information your eyes send. Cells in your brain called neurons are responsible for this processing.
The fMRI brain scans could generally match electrical activity in the brain to the basic shape of a picture that someone was looking at—such as the circle of the moon here. But there's no way for fMRI to pick up enough detail to figure out whether so
Like cells anywhere else in your body, active neurons use oxygen. Blood brings oxygen to the neurons, and the more active a neuron is, the more oxygen it will consume. The more active a region of the brain, the more active its neurons, and in turn, the more blood will travel to that region. And by using a technology called functional magnetic resonance imaging, or fMRI, scientists can visualize which parts of the brain receive more oxygen-rich blood—and therefore, which parts are working to process information.
An fMRI machine is a device that scans the brain and measures changes in blood flow to the brain. The technology shows researchers how brain activity changes when a person thinks, looks at something, or carries out an activity like speaking or reading. By highlighting the areas of the brain at work when a person looks at different images, fMRI may help scientists determine specific patterns of brain activity associated with different kinds of images.
The California researchers tested brain activity by having two volunteers view hundreds of pictures of everyday objects, like people, animals, and fruits. The scientists used an fMRI machine to record the volunteers' brain activity with each photograph they looked at. Different objects caused different regions of the volunteers' brains to light up on the scan, indicating activity. The scientists used this information to build a model to predict how the brain might respond to any image the eyes see.
In a second test, the scientists asked the volunteers to look at 120 new pictures. Like before, their brains were scanned every time they looked at a new image. This time, the scientists used their model to match the fMRI scans to the image. For example, if a scan in the second test showed the same pattern of brain activity that was strongly related to pictures of apples in the first test, their model would have predicted the volunteers were looking at apples.
Using the model, the scientists successfully used the brain scan to predict which photo one volunteer was looking at 92 percent of the time. For the other volunteer, the scientists were correct only 72 percent of the time.
But don't count on reading your friend's mind next time she has a secret to tell. While the results are intriguing, mind-reading brain scans won't be on the horizon anytime soon, the researchers note. When volunteers viewed a much larger number of photos—a total of 1,620 pictures—the scientists had a much more difficult time predicting what the volunteers were looking at, based on the brain scan alone. In this situation, the scientists chose the correct brain scan–photograph pair only half the time with one volunteer and only a third of the time with the other—Jennifer Cutraro
From The American Heritage® Student Science Dictionary, The American Heritage® Children's Science Dictionary, and other sources.
neuron A cell of the nervous system. Neurons, also called nerve cells, send and receive signals in the form of electric impulses from other nerve cells. A bundle of nerve cells is called a nerve.
cell The most basic part of a living thing, made up of a jelly-like substance called cytoplasm that is enclosed by a thin membrane. The cells of plants and animals have a nucleus, which contains the genes and other structures. The cells of green plants and some algae have chloroplasts, which is where photosynthesis takes place.
brain The main part of the nervous system in vertebrates that controls all body activities, such as breathing and walking. In humans, the brain is the center of speech, memory, thought and feeling. The brain is protected by the bones of the skull and is connected to the spinal cord.
fMRI fMRI stands for functional magnetic resonance imaging. fMRI is largely a research technique that uses MRI scanners to visualize activity in the brain over time. MRI itself produces non-moving, but highly detailed images of the molecules that make up a substance, especially the soft tissues of the human body. It works by taking advantage of nuclear magnetic resonance. MRI is used in medicine to diagnose disorders of body structures that do not show up well on x-rays.
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Callaway, Ewen. 2008. Pick a photo, any photo. Science News 173(March 15):173–174. Available at http://www.sciencenews.org/articles/20080315/note14.asp .