Even if we don’t feel the pain, seeing a physical injury in a movie makes many people shudder. A reaction that baffled scientists, but that they now explain by analyzing how the brain maps what it sees onto the body itself, thus ‘simulating’ a tactile sensation.
A study that publishes Nature points out that this sensation, as if the pain jumped directly from the screen to the skin, occurs because the brain not only observes, but simulates what it sees.
Thus, films and other images that show injuries can activate brain regions that process touch in a very organized way, according to researchers from the universities of Reading (United Kingdom), Free University of Amsterdam and Minnesota (USA).
Parts of the brain that were originally thought to only process vision are also organized according to a ‘map’ of the body, allowing what we see to trigger echoes of tactile sensations.
“When you see someone being tickled or hurt, the areas of the brain that process touch are activated in patterns that match the part of the body affected,” said the article’s lead author, Nicholas Hedger, cited by the University of Reading.
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The brain “maps what you see in your own body, ‘simulating’ a tactile sensation even if nothing physical has happened to you” and it is an interaction that also works in the opposite direction.
When you go to the bathroom in the dark, tactile sensations help the visual system create an internal map, showing, Hedger said, how our different senses “cooperate to generate a coherent picture of the world.”
To demonstrate how it is possible for the sense of touch to be activated by visual information alone, the researchers developed novel methods to analyze the brain activity of 174 people while they watched films such as ‘The Social Network’ and ‘Inception’.
The researchers found that brain regions traditionally considered responsible for processing purely visual information showed patterns that reflected sensations in the viewer’s body and not just what appeared on the screen.
These visual regions contain ‘maps’ of the body similar to those usually found in the areas of the brain responsible for processing touch, that is, the ‘machinery’ that the brain uses to process touch is ‘integrated’ into our visual system, explains a statement.
The study discovered two ways these body maps align with visual information. In the dorsal (higher) regions of the visual system, they coincide with where things appear in our field of vision.
The parts of the brain tuned to the sensations of the feet were also tuned to the lower parts of the visual scene, and those of the face to the higher parts.
In ventral (lower) regions, body maps match the body part being viewed, regardless of where it appears in the visual scene.
These discoveries may have clinical applications and, according to Hedger, “could transform the way we understand disorders such as autism.”
Many theories suggest – he recalled – that internally simulating what we see helps us understand other people’s experiences, and these processes may function differently in autistic people.
Traditional sensory testing “is exhausting, especially for children or people with clinical conditions,” but these brain mechanisms can now be measured while someone “simply watches a movie, opening up new possibilities for research and diagnosis.”
With information from EFE
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