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Imagine a world where everyone has the same face. It would be a world very different from the one we know. In our world where faces are different, faces convey essential information. For example, most of us can recognize the face of a celebrity even if it only appears a split second or the face of an old friend in college, even after decades without seeing it. Many of us can feel the mood of another important man who comes from facial expression. Often, we can determine if a person is trustworthy just by looking at his face. Despite intensive research, the way the brain performs all these behaviors remains a mystery.
A new study published in Neurology, the medical journal of the American Academy of Neurology (January 22, 2019 issue), identifies for the first time the neurons of the human visual cortex that respond selectively to faces. The study was conducted by Dr. Vadim Axelrod, head of the Cognition and Cognition Lab at the Gonda Multidisciplinary Brain Research Center (Goldschmied) of Bar-Ilan University, in collaboration with a team of the Brain and Spinal Cord Institute and Pitié Salpêtrière Hospital (in charge: Prof. Lionel Naccache).
Researchers have shown that neurons in the visual cortex (near the surface of the fusiform surface) respond much more strongly to faces than to landscapes or objects in a city. A strong response was found both for the faces of famous people (eg, Charles Aznavour, Nicolas Sarkozy, Catherine Deneuve, Louis De Funes) and for the unknown faces of the participant in the experiment. In an additional experiment, the neurons showed a selectivity towards the human and animal faces appearing in a film (extracted from Charlie Chaplin). The circus).
"In the early 1970s, Professor Charles Gross and his colleagues discovered the visual cortex neurons of macaques monkeys reacting to faces.In humans, the face selection activity did the following. subject of much research, mainly by means of non-invasive tools such as functional magnetic resonance imaging (fMRI) and electrophysiology (EEG) ", explains the main author of the article, Dr. Axelrod. "Strikingly, the neurons of the face in the posterior temporal visual cortex have never been previously identified in humans." In our study, we had a very rare opportunity to register the neurons of the face in the posterior temporal visual cortex. Neural activity in a single patient while micro-electrodes were implanted near the fusiform face Zone – the largest and probably the most important selective region of the human brain face. "
The best-known neurons that respond to the faces are probably the "Jennifer Aniston's cells" – the medial temporal lobe neurons that respond to different images of a specific person (eg, Jennifer Aniston in the original study published in Nature Quiroga and his colleagues in 2005). "But the neurons of the visual cortex that we have reported here are very different from the neurons of the internal temporal lobe," says Dr. Axelrod. "First, the neurons in the visual cortex respond vigorously to any type of face, regardless of the person's identity, and secondly, they respond much earlier, specifically, in our case, a strong response could be observed in the 150 milliseconds after displaying the image., "Jennifer Aniston's cells" usually take 300 milliseconds or more to respond. "
The present results provide unique insights into the functioning of the human brain at the cellular level during facial treatment. These discoveries also help to better understand the mechanisms of the face among species (monkeys and humans). "It's really exciting," says Dr. Axelrod, "after almost half a century since the discovery of facial neurons in macaque monkeys, it is now possible to demonstrate similar neurons in humans." . "
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Material provided by Bar-Ilan University. Note: Content can be changed for style and length.
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