Movie Experiment Hints That Our Brains Work Alike
for National Geographic News
|March 11, 2004|
Do we all see the natural world in the same way?
To answer that age-old question, a group of Israeli researchers went to the movies. Using magnetic resonance imaging (MRI), the scientists monitored the brain activity of volunteers as they watched the classic Clint Eastwood Western The Good, the Bad, and the Ugly.
Their surprising answer: Our brains tick together.
The research showed the brain-activity patterns of people watching the same movie look very similar, regardless of their gender and age. Viewers tend to focus on the same faces and objects, even when they are looking at complex scenes.
"This similarity was so strong that you could take a small part of one subject's brain and predict what will be the activity in the corresponding part of the brain of another person watching the same movie," said Rafael Malach, of the Weizmann Institute of Science in Rehovot, Israel, who co-authored the study.
The experiment also showed that different brain areas actually pick up different types of scenes, from a close-up of an actor to an outdoor scene.
"Although we have a strong subjective feeling of unity when we watch a movie, this is actually built up of a sort of orchestrated jam session of activity in many brain areas," said Malach. "Each becomes active depending on what is being shown on the screen."
The findings could help neuroscientists better map and understand our brains, and it may even help diagnose mental diseases in the future.
The research is published in this week's issue of the journal Science.
Scanning the Brain
Neuroscientists and psychologists have long debated the question: To what extent do our brains operate alike?
Typical neuroimaging studies have generally been simple, abstract, and highly controlled. Volunteers may have been asked to move dots on a computer screen or respond to single-object pictures.
The Israeli researchers, on the other hand, gave their subjects complete freedom in watching the movie. Volunteers were placed in an MRI machine. Equipped with earphones, they watched the film on a screen inside the MRI machine while their brains were scanned.
Malach says the researchers chose The Good, the Bad, and the Ugly partly because it is one of the favorite movies of the lead author of the study, Uri Hasson.
"We just let [the movie] run for half an hour," Malach said. "The movie contains many object categories at the same time. It is dynamic, audiovisual, and has rapidly changing language and emotional aspects.
Although the subjects had complete freedom in watching the movie, researchers found a striking similarity in the activity pattern across large parts of the subjects' brains.
"It appears that all the brains of the subjects watching the movie tick together in a similar fashion," Malach said.
The study also showed that different brain areas focus on certain frames and short scenes that fit the brain area's specialization. Using special computer software, the scientists were able to identify what images different brain areas pick up on.
"An area that was suspected as being involved in face recognition selected from the movie only those scenes that contained close-ups of faces. While a nearby area that was suspected of dealing with navigation was active mainly when outdoor scenes were shown," Malach said.
"Perhaps most interesting of all, we found that an area of the brain associated with the sense of touch was active whenever delicate hand movements were shown."
However, the researchers did find some regions of the activated cortex that could not be predicted from another individual's brain activity. Embedded among the more "cooperative" portions of the brain, this region showed a completely individualistic pattern of activation during the movie, without any similarity between subjects.
"We speculate that these might be related to some function which is indeed intrinsic to each [person] and not related to external stimuli," Malach said.
The scientists hope the movie experiment may offer a model for probing unknown brain-activity patterns in regions that are typically not reached by conventional experiments.
"This opens the way to rapid discovery of new specializations in the human brain, because it has the advantage of allowing us to study the brain without the need to assume ahead of time what each area is doing," Malach said.
Malach believes the research will help scientists map little-understood brain areas, and give scientists better insight into what kinds of images engage us and attract our attention and focus.
"We also anticipate that it could be used as a rapid and sensitive diagnostic tool for mental cases, such as autism, Alzheimer's, retardation, and perhaps even schizophrenia," Malach said.
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