My hobby is analyzing real-time social media from the perspective of neuroscience. I’m fascinated by the analogy between Twitter and the brain. The recent discussions about the etiquette of ‘thank you’ posts on Twitter got me thinking – how do neurons in the brain handle thank yous?Pat on Back

At first it seems like a silly question. Upstream neurons don’t thank downstream neurons for passing on the message they sent. A pre-synaptic neuron sends neurotransmitters to the post-synaptic neuron and that would seem like the end of it. Right? Or is it?

In fact, if the post-synaptic neuron fires soon after the pre-synaptic neuron sends it a message, the strength of the synapse between the two 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 neuron for the equivalent of a retweet by the post-synaptic neuron, the pre-synaptic neuron’s gratitude (to stretch the analogy) manifests itself as a strengthening of the synapse, the equivalent of the ‘social bond’ between the two neurons.

The equivalent response on Twitter would be if I started posting more content that I think will be appreciated by someone who has shown a tendency to retweet my posts in the past – in other words, sending more good stuff their way.  In a sense, the neurons are just ‘doing their job’ of passing on the best information they can find to those other neurons they think will listen, rather than explicitly greasing the skids of communication by exchanging extra messages expressing gratitude.

Perhaps this disconnect between how effective communication appears to happen in the brain (without thank yous) and how messages are passed on Twitter today is part of my ambivalence about ‘thx for the RT!’ posts.

But as we see from the wild west nature of real-time social media today, and last nights successful attack that took down Twitter, the Global Brain is still in the early process of development.  Maybe before it got so complex and sophisticated, the brain was more like Twitter?

This is purely speculation, but I strongly suspect that when brains were more primitive, and proto-neurons in those primitive brains were trying to figure out whether or not it was worth talking to their neighbors, there must have been something that was ‘in it for them’ to encourage message passing.

Perhaps like vampire bats share blood to build social ties, early neurons might have shared chemicals to help nourish each other and build supportive networks. The survival value of this ‘cellular food’ might have encourage the initial exchanges, which got co-opted later by natural selection for communication purposes as multi-cellular organisms evolved.

But a more likely possibility seems to be that proto-synapses between proto-neurons served a communication function from the start. A rather dense 2009 paper from Nature Neuroscience by neuroscientists at the the University of Cambridge on the evolution of the synapse seems to support this idea:

“Strikingly, quintessential players that mediate changes dependant on neuronal activity during synaptic plasticity are also essential components of the yeast’s response to environmental changes.”

In other words, these scientists appear to be suggesting that early semi-independent single cell organisms may have developed proto-synapses to communication information about their shared environment, like the presence of food or toxins nearby. Perhaps through communication, these early colonies of cells might have reacted in concert, and thereby coped more effectively with threats or opportunities presented by their shared environment.  Such ‘communication for a common cause’ would have had survival advantage for the cell colony, encouraging its elaboration through the process of natural selection.  Anthropomorphically speaking, the cells would have been saying ‘if we listen to each other, we can all get ahead.’

All this points to the content of the message itself as as the carrier of value in these early colonies of cells, without need for explicit exchange of ‘thank you’ messages. Listening and being heard were both of intrisic value to individual primitive cells, and to the colony as a whole.

So can we get away with such a ‘thankless’ model on Twitter, or is a virtual pat on the back in return for digital kindness, in the form of a thank you post for retweets, still necessary to grease the skids of communication in the rapidly evolving global brain?