When a group of people tries to decide how to carry out an important task, it is sometimes said that the pivotal discussions do not happen in large, well-attended meetings, but in one-on-one conversations around the water cooler. It turns out that among individual neurons in our brains, the same may hold true.
Likening the process to the sort of casual conversations one might have at a cocktail party, William Bialek and his research team have found that retinal ganglion cells, the nerve cells along the back of our eyes that transmit visual signals to the brain, organize their actions based on communications they have with other individual cells rather than on group-style discussions. The findings, derived from experiments with and mathematical models of groups of 40 cells in the retinas of salamanders, could shed light on how brain cells work as a team.
'We have found that it is possible to understand the group behavior of neural cells based solely on knowledge of these pair interactions,' said Bialek, who wrote the research paper with Princeton colleagues Michael Berry, Ronen Segev and Elad Schneidman. 'From these pair-wise communications, a consensus emerges as to what message will be sent from the eye to the brain. But it comes from many small discussions, not one large one.'
'By eavesdropping on the 'conversations' of individual nerve cells, these researchers learned to predict how small groups of nerve cells in the eye would behave,' said biophysicist C. John Whitmarsh. 'This really is a fantastic result, and could help us understand how brain cells work together to make decisions.'
'It seems that cells at the cocktail party talk primarily, perhaps exclusively, in pairs alone. No one belongs to a group, or takes dictation from a leader, but everyone bases their behavior on what we might call 'informed pair conversations.' They participate in as many of them as they can, listen as much as they can, then act,' Schneidman said.
According to this analogy, the retinal cells would transmit messages based on the information culled from these 'conversations.' However, Bialek said, as at any party, there are subtleties at work as well. 'Just as you might know from past experience that you tend to sympathize with one party guest quite often, but are put off by another, the opinions you draw from different conversations are not all weighted equally,' he said. 'You might nod politely at one person's argument, while agreeing strongly with another, even though they had both come down on the same side of an issue. Nerve cells seem to react to one another in the same way.'
'The evidence pointed us to a more startling discovery, which is that buried in the apparent randomness there are subtle relationships between pairs in the group, and you can actually determine what the group's decision will be, based solely on an awareness of these relationships between pairs,' Berry said. 'Our model does not exclude the possibility that larger groupings within the 40 cells exist. What it shows is that either way, they do not need to be considered to predict the final outcome.' >from *Researchers find nerve cells talk in pairs*. April 20, 2006
> groups perform better than the best individuals at solving complex problems. effects of group size: 'groups of three, four, or five perform better on complex problem solving than the best of an equivalent number of individuals.' april 23, 2006
> disorder-induced synchronization. april 14, 2006
> physics of friendship. 'by comparing people to mobile particles randomly bouncing off each other, scientists developed a new model for social networks. the model fits with empirical data to naturally reproduce the community structure, clustering and evolution of general acquaintances and even sexual contacts.' march 10, 2006
> how the brain makes a whole out of parts. 'beginning to reveal how large networks of neurons in the brain extract meaning from the eye image.' january 17, 2006
> why the brain has gray and white matter. 'brain functionality benefits from high synaptic connectivity and short conduction delays.' january 27, 2006
> steps to integrate new neurons into brain's existing operations. december 22, 2005
> swarm intelligence. 'a system whereby the collective behaviours of (unsophisticated) agents interacting locally with their environment cause coherent functional global patterns to emerge.' may 20, 2005
> how animals coordinate their actions. 'group coordination arises naturally from two basic instincts: the need to stay in a group; and the desire by some individuals to act on their own information about where to go.' march 18, 2005
> cooperation evolution. october 8, 2003
> ants community: a perceptual achievement. 'what seems to matter to an ant is the pattern of interactions it experiences rather than a particular message or signal transferred at each interaction.' may 7, 2003
> commons-based peer production in the digitally networked environment. 'groups of individuals successfully collaborate on largescale projects following a diverse cluster of motivational drives and social signals, rather than either market prices or managerial commands.' december 19, 2002
> it takes two to speak the truth — one to speak and another to hear
sonic flow| permaLink
> from the eye to the brain [stream]
from the eye to the brain [download]