Mapping the brain: New technique poised to untangle the complexity of the brain

April 10, 2011
Mapping the brain: New technique poised to untangle the complexity of the brain
The gold colour shows information superhighways in the brain: the gold is a protein making up myelin, which speeds the conduction of electrical signals along nerve cells, allowing us to think more quickly. Courtesy of Professor David Attwell (UCL Neuroscience, Physiology & Pharmacology)

( -- Scientists have moved a step closer to being able to develop a computer model of the brain after developing a technique to map both the connections and functions of nerve cells in the brain together for the first time.

A new area of research is emerging in the neuroscience known as 'connectomics'. With parallels to genomics, which maps the our genetic make-up, connectomics aims to map the brain's connections (known as 'synapses'). By mapping these connections – and hence how information flows through the circuits of the – scientists hope to understand how perceptions, sensations and thoughts are generated in the brain and how these functions go wrong in diseases such as Alzheimer's disease, schizophrenia and stroke.

Mapping the brain's connections is no trivial task, however: there are estimated to be one hundred billion nerve cells ('neurons') in the brain, each connected to thousands of other nerve cells – making an estimated 150 trillion synapses. Dr Tom Mrsic-Flogel, a Wellcome Trust Research Career Development Fellow at UCL (University College London), has been leading a team of researchers trying to make sense of this complexity.

"How do we figure out how the brain's neural circuitry works?" he asks. "We first need to understand the function of each neuron and find out to which other brain cells it connects. If we can find a way of mapping the connections between nerve cells of certain functions, we will then be in a position to begin developing a to explain how the complex dynamics of neural networks generate thoughts, sensations and movements."

Nerve cells in different areas of the brain perform different functions. Dr Mrsic-Flogel and colleagues focus on the , which processes information from the eye. For example, some in this part of the brain specialise in detecting the edges in images; some will activate upon detection of a horizontal edge, others by a vertical edge. Higher up in visual hierarchy, some neurons respond to more complex visual features such as faces: lesions to this area of the brain can prevent people from being able to recognise faces, even though they can recognise individual features such as eyes and the nose, as was famously described in the book The Man Who Mistook Wife for a Hat by Oliver Sachs.

In a study published online today in the journal Nature, the team at UCL describe a technique developed in mice which enables them to combine information about the function of neurons together with details of their synaptic connections.

The researchers looked into the visual cortex of the mouse brain, which contains thousands of neurons and millions of different connections. Using high resolution imaging, they were able to detect which of these neurons responded to a particular stimulus, for example a horizontal edge.

Taking a slice of the same tissue, the researchers then applied small currents to a subset of neurons in turn to see which other neurons responded – and hence which of these were synaptically connected. By repeating this technique many times, the researchers were able to trace the function and connectivity of hundreds of nerve cells in visual cortex.

The study has resolved the debate about whether local connections between neurons are random – in other words, whether nerve cells connect sporadically, independent of function – or whether they are ordered, for example constrained by the properties of the neuron in terms of how it responds to particular stimuli. The researchers showed that neurons which responded very similarly to visual stimuli, such as those which respond to edges of the same orientation, tend to connect to each other much more than those that prefer different orientations.

Using this technique, the researchers hope to begin generating a wiring diagram of a brain area with a particular behavioural function, such as the visual cortex. This knowledge is important for understanding the repertoire of computations carried out by neurons embedded in these highly complex circuits. The technique should also help reveal the functional circuit wiring of regions that underpin touch, hearing and movement.

"We are beginning to untangle the complexity of the brain," says Dr Mrsic-Flogel. "Once we understand the function and connectivity of spanning different layers of the brain, we can begin to develop a computer simulation of how this remarkable organ works. But it will take many years of concerted efforts amongst scientists and massive computer processing power before it can be realised."

The research was supported by the Wellcome Trust, the European Research Council, the European Molecular Biology Organisation, the Medical Research Council, the Overseas Research Students Award Scheme and UCL.

"The brain is an immensely complex organ and understanding its inner workings is one of science's ultimate goals," says Dr John Williams, Head of and Mental Health at the Wellcome Trust. "This important study presents neuroscientists with one of the key tools that will help them begin to navigate and survey the landscape of the brain."

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5 / 5 (2) Apr 10, 2011
We live in such interesting times!

Knowing how the brain works would be a major leap in developing AI and maybe brain augmentation? I really hope these people can pull it off.
5 / 5 (1) Apr 10, 2011
Jaeherys, see Henry Markham Blue Brain project. For example, see his lecture http://www.youtub...R8Z-e_GU
3 / 5 (1) Apr 10, 2011
We live in such interesting times!

I completely agree, I'm so excited for the singularity! I can't wait until we have a super computer that can map a brain out fully. This will allow for extreme information on the brain because we could tweak any part of the brain (neuron by neuron or hemisphere by hemisphere) and can find out how it affects the brain and why! Or like you said, AI could adapt these super-minds (minds created beyond their potential, because they exist in a computer that we can constructively build on and manipulate!) Ahh, I'm sitting back just waiting :)
3 / 5 (2) Apr 10, 2011
Weeeell, with the multi-processor server boards, and multi-core processors we have, in addition the ~800 stream processor, gigabyte memory video cards we have now, it should soon be possible to construct a general purpose computer capable of running a virtual machine consisting of billions of "neuron" objects, each in it's own seperate thread. This would be an attempt to simulate human intelligence by simulating nerve activity in the brain.

Alternatively, we could eventually write multi-threaded "scripts" which are generalized and flexible enough to both learn and improve themselves by re-writing their own programing, like "The Doctor" in Star Trek: Voyager.

However, I don't necessarily think they should ever be truly "self aware" because that would obviously be dangerous.

Tinkering with copying the human brain might not even be moral or ethical. Suppose you do have a human brain simulation which is similar to human intelligence. What are it's rights at that point?
1 / 5 (5) Apr 10, 2011
The same as a persons. It's inevitable and the first few (many?) AI will inevitably be shit on until they fight for their rights. Then we lose.
not rated yet Apr 10, 2011
Tinkering with copying the human brain might not even be moral or ethical.

In your case we will make an exception...

But seriously, I have been a fan of brain sim from the start of the blue brain project and see any advances here as a plus. I do wonder how the hardware aspect is progressing -- a lot of labs promised some really cool "neuron" chips that would be capable of "actually" simulating parallel processing. Is that even necessary with the current trajectory of computing power?
not rated yet Apr 10, 2011
Is that even necessary with the current trajectory of computing power?

No, not really.

Assume this article is correct,a nd say we have 150trillion synapses, and lets further assume each synapse is representative of a byte of data on average. That would only come to, on average, about 1 kilobyte of memory per neuron.

With the proper financial support, it is already possible to construct specialized circuitry GREATLY exceeding that density of data storage, AND a processor inside the volume of a neuron, not even counting the length and volume of the axons and dendrites.

Using 32nm process and wasting 90% of space in all 3 dimensions for power, cooling, and scaffolding, it should be possible to put a processor and around 155 kilobytes of RAM, cache, and registers inside the volume of the body of a neuron, if you make use of all 3 dimensions.

155 kilobytes isn't much, until you realize it's in the same volume as a neuron which probably represents 1 kilobyte or less.
not rated yet Apr 10, 2011
So I mean think about it...

"eventually" well get to a point where we can put more than 100 billion processors in the volume of a human brain, with around 15.5 terrabytes of RAM. Actually, we could already do that theoretically, it'd just burn up from waste heat and cross talk.

But by around 2020 we are going to have sub-11nm process and moving more and more into the 3rd dimension. So 11nm and 3-d architecture has the potential to be around 760,000 times more transistors per unit volume compared to existing 32nm 2-d architecture.

3-d architecture with 11nm transistor gates and 90% wasted space for power, cooling and scaffolding in each dimension would still allow 751 TRILLION transistors per cubic centimeter volume...

Average cranial capacity modern human: 1400cm^3
Max: 1800cm^3

So then in the space of a human brain, within a decade or so, we'll be able to put between 48 Quadrillion and 56 Quadrillion BYTES worth of transistors in the volume of a human brain...
not rated yet Apr 10, 2011
So then in the space of a human brain, within a decade or so, we'll be able to put between 48 Quadrillion and 56 Quadrillion BYTES worth of transistors in the volume of a human brain...

If the maths are correct then I see your logic here. The only issue is how truly complex the subtle changes in gene expression are (which lead to ion channel creation/modification, mechanisms of learning, disorders, etc). A detailed simulation may necessitate magnitudes more than the bytes per synapse you mentioned above.
3 / 5 (1) Apr 11, 2011
"I'm so excited for the singularity!"
the singularity is all I ever think about and it scares the bleep out of me. not a fan.. I mean it's a completely uncontrolled experiment! you're bringing a new sort of thing that's way smarter than you into being with no idea of what it will want to do.. it's actions are not predictable.. ok ya, "because we can." but I'm not excited.. I'm scared out of my mind.. I think that's a more wise response..
not rated yet Apr 11, 2011
There are dangers and benefits inherent to any new technology. If we wish to progress, and more importantly progress first so that we can set an acceptable precedent before less scrupulous groups try their hand, we can't let fear of the unknown hinder the responsible study and eventual application of these emergent technologies which hold such profound potential.

Scientific advancement has empowered us so very much. I'm glad those in the past took the risks and I'm sure that 100 years from now, we here or our descendants will feel the same way about today.

At least take heart in the fact that during the entirety of the Cold War, not a single nuclear missile was fired with destructive intent. As a measure of our species; that has to count for something.

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