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Saturday, October 24, 2009

why is yawning contagious?


Answer:
Heere are excerpts from the source:
In an effort to find the answer, the Finnish government recently funded a brain scanning study. The results turned up some hard-to-interpret, possible clues. It also confirmed the obvious: yawn contagion is largely unconscious. Wherever it might affect the brain, it bypasses the known brain circuitry for consciously analyzing and mimicking other people’s actions.This circuitry is called the “mirror-neuron system,” because it contains a special type of brain cells, or neurons, that become active both when their owner does something, and when he or she senses someone else doing the same thing. Mirror neurons typically become active when a person consciously imitates an action of someone else, a process associated with learning. But they seem to play no role in yawn contagiousness, the researchers in the new study found. The cells are have no extra activity during contagious yawning compared with during other non-contagious facial movements, they observed.Brain activity “associated with viewing another person yawn seems to circumvent the essential parts of the MNS [mirror neuron system], in line with the nature of contagious yawns as automatically released behavioural acts—rather than truly imitated motor patterns that would require detailed action understanding,” wrote the researchers, with the Helsinki University of Technology and the Research Centre Jülich, Germany. The findings are published in the February issue of the research journal Neuroimage.But if seeing someone yawn doesn’t activate these centers, what does it do to the brain? The researchers found that it appears to strongly activate at least one brain area, called the superior temporal sulcus. But this activation was unrelated to any desire to yawn in response, so it may be irrelevant to the contagion question, the researchers added.Possibly more significant, they wrote, was the apparent deactivation of a second brain area, called the left periamygdalar region. The more strongly a participant reported wanting to yawn in response to another person’s yawn, the stronger was this deactivation. “This finding represents the first known neurophysiological signature of perceived yawn contagiousness,” the researchers wrote.Exactly what the finding means is less clear, they acknowledged. The periamygdalar region is a zone that lies alongside the amygdala, an almond-shaped structure deep in the brain in the area of the side of the head. The periamygdalar region has been linked to the unconscious analysis of emotional expressions in faces. Why it would be deactivated in tandem with yawn contagion is unclear, the researchers said.
Further details can be had from the site.
VR
good question the REAL reason is genetic encoding, when we were apes yawning was a way to express dominance by showing our teeth, and it makes us have the compulsion to display ours as well, there are many other examples of this, like why people go crazy during a full moon, or why we are afraid of spiders %26 snakes just to name a few
Though the response from Sarayu was truly enlightening, the reason for this is still not clear or answered.
simply - its related to how sympathetic the person is

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