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The Human Brain has a Network Backbone
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The Human Brain has a Network Backbone

The human brain is still full of mysteries that we will need to solve if we are ever to interface with it directly on a long-term basis, particularly when interfacing an artificial (or purely virtual) embodiment through it. In order to re-embody the mind in another body, we really have to know what we are doing, and which brain section does what and why.

Towards that end, an interesting discovery concerning the white matter of the brain has found evidence of a network backbone within the organ; a communications network, separate from the brain's various processing regions, that works in many ways like a system bus, ferrying information between relatively discrete processing regions.

It has long been recognised that the brain is composed of both white matter and grey matter. Grey matter, or how we traditionally think of the brain, being the only type visible from the outside, and composed of unmyelinated neurons. In contrast, white matter is myelinated, It is the fatty myelin sheaths that give white matter its distinctive colour, as well as providing insulation for the axons of neurons in the same manner as plastic sheaths insulate wires.

What eluded us was the way this white matter inside the brain, forms a scaffold for regulating communication between the unmyelinated areas.

Researchers from the University of Southern California have created a rough map of the primary nodes in this scaffold; the connections that influence the way traffic flows through all other nodes in that area of the brain.

Credit: USC Institute for Neuroimaging and Informatics

 

By using a mixture of MRI and fMRI data and a sample size of 110 individuals who agreed to have their brains scanned whilst completing the same set of mental exercises, the researchers were able to analyse the way information flowed through the white matter scaffold, and identify these core areas. Areas which if damaged, prevent information passing through their 'child' nodes on the network.

"Just as when you remove the internet connection to your computer you won't get your email any more, there are white matter pathways which result in large scale communication failures in the brain when damaged," Stated senior author John Darrell Van Horn, associate professor of neurology at the Keck School of Medicine of USC.

"Sometimes people experience a head injury which seems severe but from which they are able to recover. On the other hand, some people have a seemingly small injury which has very serious clinical effects. This research helps us to better address clinical challenges such as traumatic brain injury and to determine what makes certain white matter pathways particularly vulnerable and important."

Of course, if these points are that important to communication, it may well be that they are of interest in other research, research looking at the best points in the brain to connect to to supply artificial data or read thoughts out of. Communication is after all key: we intercept or duplicate the signals travelling from sensory and motor nerve endings to the brainstem in order to fool the brain into thinking that an amputated limb is still there, or a painful area no-longer exists. This would be doing the exact same thing in the brain itself.

Rather than trying to interface directly with the hundreds of thousands of neurons carrying out tiny, interconnected parts of a puzzle in a given brain region, if we instead connected to the communications channel between regions, it would in theory be quite possible to manipulate the processing of intricate regions of the brain without actually having to place an almost insanely complex neuroprosthetic into those regions themselves. Instead, a relatively limited and specific number of nodes could be targeted which whilst still complex and composed of many millions of neurons themselves, are not actively crunching data, just transporting it. Therefore there is far less potential for computational disruption if a neuroprosthetic is monitoring the area, or attempting to write neural codes back.

A far greater fidelity map would of course be required, along with considerable refinement in capabilities of neuroprosthetic devices. However, knowing these possibilities do exist offers new research directions, and may well ultimately make it much easier to engage in two-way communication with the neurons of the brain itself – by targeting the internal communications scaffold, rather than the active data processing regions directly.

The depth of the white matter into the brain is still a problem of course, but again this type of research is of benefit. For this research team is focussed heavily on identifying which of these nodes are most vulnerable to damage. By doing this, it becomes possible medically to predict the extent of brain damage from a given injury, and as the Assoc. professor states, explain why relatively minor injuries can have devastating effects. It shows neurosurgeons where to look and why.

For us, it has equal benefit; for those nodes most exposed to the outside, most easily damaged are also those most easily accessible, and the most likely to be the first ones to be tested via a neuroprosthetic to gain a direct brain machine interface with the brain's network backbone, for the exact same reasons.

"We coined the term white matter 'scaffold' because this network defines the information architecture which supports brain function," said Van Horn. "While all connections in the brain have their importance, there are particular links which are the major players," Van Horn said.

The researchers' paper appeared in the February 11th 2014 issue of the journal Frontiers in Human Neuroscience and is linked directly, below.

References

How our brain networks: Research reveals white matter 'scaffold' of human brain

Systematic network lesioning reveals the core white matter scaffold of the human brain (Open access paper)

Staff Comments

 


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