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The First Neural-Jack?

Neural jacks are the stuff of cyberpunk: computer interfaces that connect to a port in the lower brainstem. Interrupting it, they split or fork the input and output, such that signals that should be going to the body from the brain, go to the jack instead. The jack itself supplies basic idling instructions to keep the body alive. It also sends full sensory feedback from the body, back to the brain.

For this reason it is one of the most frustrating concepts in neuroprosthetics, and one of the most fantasied, and heavily desired interface modalities. Any physical disability melts away with such an interface, as there are literally no limits on what the virtual body can be.

Of course, we are nowhere near the creation of real neural jacks, not at this point in time. However, there is reason to believe the gap is closing, and quite fast.

The Japanese have come to several correct conclusions about the fundamental limitations of deep brain and peripheral brain implants. These conclusions may seem obvious, but then unlike most researchers, these have decided to hit the problem head-on.

Neural interfaces used for such purposes as electroencephalography are noninvasive, but suffer from relatively poor spatial and temporal resolution of signals. The type of neural interface that uses electrodes inserted in the brain and measures neuronal activities is more effective, but might leave behind irreversible lesions in the cerebrum because of the need to implant electrodes in brain tissue. Other problems with this type of neural interface include the difficulty of obtaining information about individual organs.

To counter this, researchers at Japan's National Institute of Advanced Industrial Science and Technology and Toyohashi University of Technology have been collaborating to build the first device capable of directly interfacing with the brainstem - the first real neural jack.

Hidekazu Kaneko from the Institute for Human Science and Biomedical Engineering at AIST and his team have been working to develop the primitive jack, so as to gain full access to the neural data from all organs of the body - eventually.

According to Kaneko, the electrode under development should have the capability of simultaneously measuring the action potentials of individual nerve fibers in a peripheral nerve bundle. Earlier proposals for measuring peripheral nerve activity were based on the use of sieve electrodes, needle point holder-shaped electrodes, and cuff electrodes; but these and other attempts have been unable to meet the requirement for low invasive measurement that is also able to distinguish the activity of individual nerve fibers.

To do this, the array is so tiny, the only way to photograph it, is to use an electron microscope. The image below, on the left, is one such photograph, showing the existing structure. On the right, is a diagram of one of the individual chips. Primitive they may be, however these chips are grown in place, not built, so they can be fabricated in huge numbers - one to interface with every nerve in a bundle, for example.

Currently, the electrodes have only just been implanted in organic, living tissue, namely mice. There the researchers have confirmed they are strong enough and accurate enough to read and isolate the nerve impulses from individual nerve fibres. If the arrays are patterned on both sides, it becomes possible of course to read from the nerve, and send a signal back, severing the nerve, with the neuroprosthetic between the halves. Nerve impulse signals don't notice that they have been severed of course, and electrodes transmit signals somewhat more swiftly than myelinated nerve fibres.

As this technique is practised with, there is every reason to believe it will see transference to increasing numbers of nerve fibres, even whole nerve bundles. As tiny as the chips are, they can almost be painted onto individual nerve threads, or across nerve bundles. The greatest hang-up then, is of course getting the data out in a method that makes usable sense - understanding which nerve impulse is doing what.

Where we go from there, is anyone's guess. Theory is wide open on the possibilities.

References

Local

Speeding Peripheral Nerve Machine Interfaces

Interrupting the Brainstem

Neurons as Artificial Control Circuits

Nanotech coating could lead to better brain implants

Elsewhere

Nerve interface electrodes

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