A population of neurons behaves like the active members of a social networking site such as Facebook, a new study suggests.
The population of highly active neurons has been found within the part of the brain believed to be responsible for functions like conscious thought, language and spatial reasoning, the researchers said.
Previously, scientists thought that only a small population of neurons within the brain's neocortex was doing most of the noggin's processing work; however, because they couldn't see the individual neurons, they couldn't confirm it.
However, a team of researchers has devised a way to identify and observe these highly active neurons, and they published their work in the Dec. 22 issue of the journal Neuron.
The neocortex is part of the brain's cerebral cortex — the wrinkly layer of gray matter of the brain — and it is responsible for a number of important functions, including sensory perception, motor function, spatial reasoning, conscious thought and language. The neocortex is made up of trillions of neurons.
The researchers, including Alison Barth of Carnegie Mellon University, put a fluorescent label on a gene linked to neuronal activity in mice, causing the neuron to light up when activated. First the team confirmed that most of the activated neurons actually expressed this gene, meaning the label was a good indicator of brain-cell activity. Then, they isolated the active neurons from the inactive ones using imaging techniques and recorded their activity.
These active neurons resembled the active members of a social network, like that on the website Facebook, Barth said. The other neurons resembled those delinquent Facebookers.
"It's like Facebook. Most of your friends don't post much – if at all," Barth said. "But, there is a small percentage of your friends on Facebook who update their status and page often. Those people are more likely to be connected to more friends, so while they're sharing more information, they're also receiving more information from their expanded network, which also includes other more active participants."
With these findings, researchers can begin to determine why certain brain cells are more active and how stable the activity is. The Carnegie Mellon researchers plan to study these neurons to see what, if any, role they play in learning.
It's All In The Genes
People's choice of reproductive partner is known to carry a genetic aspect. To test whether genetics also influences friend choice, James Fowler at the University of California, San Diego, and colleagues studied more than 3000 pairs of friends for which they had genotype information for both individuals. For each friendship pair, the team compared six genes thought to be associated with social behaviour.
They found that friends tended to be more alike than expected by chance for one gene, DRD2, which has been associated with a tendency to alcoholism. The researchers suggest this might be because those carrying the gene find social drinking convivial. In contrast, friends tended to be less alike than expected by chance for another gene, CYP2A6, which may be associated with an open personality. It is not clear why people should prefer friends with different versions of this gene, says Fowler.
The genetic preferences may create previously unrecognised feedback loops. If, for instance, those susceptible to alcoholism choose friends with the same propensity, they may be influenced to drink by social as well as genetic factors.