Blue Brain Project supercomputer recreates part of rodent’s brain with 30,000 neurons connected by 40m synapses to show patterns of behaviour triggered, for example, when whiskers are touched

A piece of living brain has been reconstructed in a supercomputer in what amounts to one of the most sophisticated neural simulations ever created.

The digital lump of rat brain, made from ones and zeroes, mimics the behaviour of about 30,000 neurons connected to one another by 40m synapses.

Researchers who created the simulation said its digital neurons flicker with activity seen in real rat brains and replicate patterns of electrical behaviour that are triggered, for example, when a rodent’s whiskers are touched.



The simulation draws on 20 years of measurements from rat brains and took a decade to turn into code that runs on an IBM Blue Gene supercomputer capable of solving billions of equations every 25 milliseconds.



“This is a first draft reconstruction of a piece of neocortex and it’s beautiful,” said Henry Markram, director of the Blue Brain Project at the Swiss Federal Institute of Technology in Lausanne. “It’s like a fundamental building block of the brain.”



Facebook Twitter Pinterest Blue Brain Project scientists discuss the reconstruction and simulation of neocortical microcircuitry

To create the simulation, the international team categorised rat neurons into more than 200 types and then used rules that govern how neurons are arranged to build up a virtual slice of brain tissue. There is a lot missing: there are no blood vessels, or cells that support neurons, or molecules that carry messages around the brain. The list goes on. But it is a start, said Markram, who describes the work in the journal Cell . “In the end, we need to understand how the human brain works, and this is a stepping stone towards that.

The simulation has already replicated brain activity that others have seen in real neural tissue. Neurons can fire in unison, earning them the name of chorists, while others behave like soloists and fire on their own. Others tap out a kind of neural morse code, and similar signals appears in the simulation. “If you mimic touching a whisker, we see the same pattern of firing in the digital tissue,” Markram added.



Facebook Twitter Pinterest Retrograde staining In silico retrograde staining. Photograph: BBP/EPFL 2015

The Blue Brain Project is an ambitious - many say overly ambitious – effort to reverse engineer the rodent brain, and ultimately the human brain, with a view to building a working model of the organ in a computer. Do that, the argument goes, and scientists might have a hope of understanding the neural mechanisms that underpin such extraordinary phenomena as consciousness, love and the antics of the Bullingdon Club.



But the task is formidable. Markram’s simulation of 30,000 neurons represents a mere third of a cubic millimetre of rat neocortex, a part of the brain that processes touch sensations. But the human brain is made up of 100bn neurons, connected to each other by perhaps 1,000tn synapses.



For some neuroscientists, the project is premature, and worse, threatens to suck precious funds from other areas of brain research. The European commission has put more than €1bn (£0.74bn) into the Human Brain Project, which the Blue Brain Project feeds into. Last year, more than one hundred neuroscientists threatened to boycott the project unless significant changes were made.



Peter Latham at UCL’s Gatsby Computational Neuroscience Unit in London called the work an “experimental and modelling tour de force”, but said the simulation produced little of immediate interest for neuroscientists.



Facebook Twitter Pinterest The digital reconstruction of the neocortex only represents a small proportion of the rat brain. Photograph: Dave King/Getty Images/Dorling Kindersley

“The model produced a pretty standard range of neural activity,” he said. “That’s not a bad thing. Their simulations should really be thought of as a tool, something that can be used toward a deeper understanding of the brain.”



But he was more critical of how much the work had cost. He estimates that the simulation cost at least €100m. To reconstruct a whole rat brain would probable take at least €20bn. “That is probably too much, given that what you’re buying is a really expensive rat that might not even be a rat.”



Markram sees the building of ever more sophisticated brain simulations as our best hope of ever grasping how the most complex object in the known universe works. It is easier to look under the bonnet of a computer simulation, than into the brain, to see how sparks of electricity combine into behaviour.



“One of the biggest reasons we can’t understand the brain is that we cannot map it,” Markram said. “This is a proof of concept that you can map a piece of the brain with enormous accuracy. If we can map it, we will be able to understand the detailed mechanisms of how it works.”

