The prevailing model for many years of how synapses between neurons in the brain are altered during learning has been Hebbian learning, which can be summarized as “neurons that fire together, wire together”. In other words, in two neurons fire at the same time, the connection(s) between them will strengthened.
But recent evidence in neuroscience shows the truth is actually an interested twist on this idea – a twist that could have important implications as a model of how global consciousness could emerge from real-time social media like Twitter.
In reality, synapses are modified according to a rule called Spike Time Dependent Plasticity (STDP). In a nutshell, STDP says that if two neurons fire (= spike) in rapid succession, the connection from the one that fires first to the one that fires second will be strengthened.
In other words, if neuron A reliably fires shortly before neuron B, the connection from A to B will get stronger, so that next time when neuron A fires, neuron B will be more likely to fire too. And the opposite holds as well. In this example, since the firing of neuron B lags behind neuron A, the strength of the connection in that direction (from B to A), will be weakened. You could think of it as the neural equivalent of the old saying ‘the early bird catches the worm’ – a neuron that fires first gains increasing influence on its downstream neighbors.
STDP is a simple idea, but it has been shown to be a surprisingly powerful way that the brain uses for rapid pattern recognition and classification [1][2]. It turns out that using STDP, neurons naturally learn to specialize in detecting certain patterns in their inputs, even in the presence of lots of noise.
So what in the world does this have to do with social networks? There is an intriguing analogy between networks of neurons operating by the STDP rule and the emerging structure and functioning of real-time social networks like Twitter.
Imagine a twitter user as a neuron. He/she makes the equivalent of a synapse with each of his/her followers. When a twitter user sends out a tweet, it is the equivalent of a neuron firing. Followers who receive the tweet decide whether to propagate the activity by retweeting the message, in a sense by deciding whether they too should fire in response to the tweet.
It isn’t happening exactly this way yet, but STDP would enter the picture in the following way. Suppose Bill is a follower of an influential person on Twitter like Guy Kawasaki and Bill decides one of Guy’s tweets is interesting enough to retweet. This is a clear indication that Bill finds Guy’s tweets interesting and valuable. Based on this ‘vote of confidence’ for Guy’s tweets, a yet-to-be-implemented mechanism could automatically increase the weight that Guy’s tweets are given for Bill, making Guy’s tweets more likely to show up high on Bill’s Twitter ‘dashboard’.
But what if Guy wasn’t the first to tweet the news that Bill found so interesting? The same automated mechanism could suggest to Bill that instead of (or in addition to) following Guy, Bill might like to follow another sharp Twitter personality (perhaps Nova Spivack) who beat Guy to the punch by being the first to post the content Bill found interesting.
In this way, users could be automatically steered towards following folks who are the first to post content that will interest them – towards those who are considered the ‘thought leaders’ you might say. And content creators who work hard to be the first to find and tweet interesting content will be rewarded automatically with a growing list of followers, and eventually with monetary reward if/when Scobleizer ‘attention economy’, or some other way to monetize eyeballs, emerges on Twitter.
As an added benefit, the tweets Bill receives could be automatically sorted based on how interesting they are likely to be for him. As a simple example, imagine that several of the people Bill follows and has demonstrated an affinity for in the past (by retweeting their posts) tweet about the same story. This convergence of matching input from sources that Bill weights highly suggests that Bill will find this to be very interesting content, so it should be automatically bubbled to the top of Bill’s prioritized list of tweets to read.
In this model, content generators on Twitter will compete to be the first to create good content or break important news, just as neurons in the brain compete via the STDP update rule to be the first to detect patterns in their input and shout out about it by spiking. In both systems, ‘the early bird catches the worm’.
Eventually, tools may even emerge that automatically retweet messages based on a user’s previously expressed preferences, to alert his followers of content he, and therefore they, will likely consider interesting. At that point, the virtual neurons formed by the combination of people and their automated agents on Twitter will be influencing each other and firing automatically based on the inputs they receive. On a macro scale, this will represent the equivalent of thoughts emerging in the Global Brain, in the form of rapid, coordinated firing of millions of these virtual neurons. These thoughts will propagate and potentially trigger other thoughts in the network. This massive semi-autonomous reverberation in the twittersphere could signal the emergence of a true global consciousness.
[1] Masquelier T, Guyonneau R, Thorpe SJ. Spike timing dependent plasticity finds the start of repeating patterns in continuous spike trains. PloS one. 2008;3(1):e1377. Available at: http://www.ncbi.nlm.nih.gov/pubmed/18167538.
[2] 1. Masquelier T, Hugues E, Deco G, Thorpe SJ. Oscillations, Phase-of-Firing Coding, and Spike Timing-Dependent Plasticity: An Efficient Learning Scheme. Journal of Neuroscience. 2009;29(43):13484-13493. Available at: http://www.jneurosci.org/cgi/doi/10.1523/JNEUROSCI.2207-09.2009

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December 7, 2009 at 9:58 pm
TweetStream: An App to Drive the Global Brain « Thoughtful Cog Blog
[...] Cog Blog Just another WordPress.com weblog « Twitter and the Global Brain TweetStream: An App to Drive the Global Brain December 7, 2009 A few days ago in a post [...]
December 18, 2009 at 3:15 pm
Do Neurons Say Thank You? « Thoughtful Cog Blog
[...] neurons is strengthened according to the spike time dependent plasticity (STDP) rule I discussed previously. So while there is no explicit acknowledgment or ‘thank you’ by the pre-synaptic [...]
December 20, 2009 at 10:17 pm
Towards a web of activity streams realizing the synaptic web paradigm « web2society
[...] response post). He describes how knowledge about neural learning could apply to Twitter (‘Twitter and the Global Brain’) and how this could lead to intelligent applications that (among other things) further help you [...]
January 1, 2010 at 2:51 pm
The Sentient Web and an Autonomous Economy « Thoughtful Cog
[...] could be an alternative route to the Global Brain I previously envisioned as the end result of the TweetStream application. By whichever route get [...]
January 4, 2010 at 1:41 am
Mathijs van Meerkerk
I think you are right. I experience this in my own twitter use. When I see something I like the value of that connection raises. When I see something I have already seen before the connection value is lowered. This is essentially true when I was first tweeting it. It feels like somebody is stealing your find.
January 4, 2010 at 2:25 am
Dean Pomerleau
Exactly! What I really wish for Twitter client that decodes short URLs and will tell me if the link in a tweet is to a story I’ve already read. I can’t tell you how many times I click on what looks like an interesting link only to find that I’ve read it a day or two before. Often the description in the tweet is different enough that I don’t recognize it as the same article until I’ve clicked on it. That doesn’t seem like it should be too difficult to implement with cookies and such…
January 4, 2010 at 6:27 pm
Moving Social Media from Talk to Positive Change – One Pothole at a Time « Thoughtful Cog
[...] I’m hopeful an even bigger and better example will happen soon in the form of a regime change in Iran, thanks in part to Twitter. As I observed recently, Twitter has given the citizens of Iran a way to tell the story of their quest for freedom to the world in real-time and in a way that engages public interest, at a time when traditional media channels have been locked out by their oppressive government. I wish them the best of luck, and will be tracking the events on Twitter as they unfold. When (not if) they succeed, it will be an important milestone for the emerging Global Brain. [...]
October 19, 2011 at 10:03 am
Leaders & Social Media: 5 Reasons to Engage « Leading in Context
[...] Dean Pomerleau, a researcher at Intel labs Pittsburgh links Twitter to brain research on his blog ‘Thoughtful Cog” in a post called “Twitter and the Global Brain.” Imagine a Twitter user as a neuron. [...]