The holodeck: Neural interface

In the last few weeks I have examined a few technologies that could function like a holodeck. Today I’ll examine the potential of the neural interface a hypothetical matrix-style technology.

A neural interface is a device that links directly to and interacts with your brain. Werther via a direct connection like in The Matrix or via a non-invasive method, the neural interface promises to be the ultimate holodeck experience even if it seems a little scary as well.

for a realistic holodeck experience you’d need three things. The first is that the computer understands what the hell you are trying to do. That your brains signal for turning left is actually translated into a left turning movement. with a tried and tested method like EEG this can be done today even if it is a little rudimentary and not quite exact. Luckily the brain can adapt and learn and increase efficiency of EEG based controllers (the brain waves the machine reads become more distinct when using it regularly.

Though EEG has been able to give us basic control of computers they are limited. The EEG only reads general brainwaves but does not have the resolution required for the fine motor control you’d need to play a first person shooter for instance. A better bet might be a fMRI. The fMRI measures the blood flow to the brain. The more blood flows to a certain part the more active it is. The fMRI has the advantage that it can measure the entire brain not just the outer layer. The fMRI also has the potential of being way more accurate then an EEG. Downsides to the fMRI are that it works with magnets and thus needs to be shielded from the rest of the world (unless you want to pry the cutlery from the wall each day.) Also the fMRI is the size of a small room and gets bigger if higher resolutions are required though advances in nanotechnology might decrease the size eventually.

A third method would be by inserting a network of small sensors into the brain capable of reading brain activity on a smaller scale then EEG. Downside to this obviously is that you’d need brain surgery with all the risks of complications. We’d even be able to let brain cells directly interact with the chips if we want to.Don’t worry about needing to plug cables into your spine though. These chips would probably be accessed via a wireless technology.

Second thing you’d need is that the computer output is translated into sensory input again. The easiest way to do this is just using current technology. TV’s, headphones, speakers, vibration in game controllers are all designed to translate computer output into sensory input. Trouble is that even the best of these are not realistic. Even advanced simulators are clearly not real.

Luckily we don’t need our senses to create sensory input because all sensory input is processed in the brain. And in the brain alone can we make sense of what our senses detect. By directly stimulating the brain you can create false sensory input. In effect you create the holodeck within your head. experiences gained this way would be indistinguishable from real experiences (except maybe for the fact you are able to fly of course.) Again there are basically two ways of doing this. Invasive or non-invasive.

The non-invasive methods work by stimulating your brain either via electricity tDCS or magnetism TMS. They work by activating your neurons so that they start firing signals to other neurons. In this way you can trick the senses into seeing, hearing and feeling things that are not actually happening. One thing to worry about though is whether this would create a double image so that you’d not only see the ‘holodeck’ image but also what your eyes actually see. (I imagine that you could get quite sick from a double input quite quickly not unlike seasickness.) The viability of either system as a sensory input device is quite questionable as well. Can we actually fire individual neurons in the right pattern? Can we penetrate the brain deeply enough to create realistic input? Because they are non invasive you need to penetrate the brain from the outside which is quite tricky as you can imagine and currently TMS and tDCS can only stimulate large parts of the brain (in terms of brain tissue even a cubic millimetre is a large part).

The invasive method is quite easy (in theory at least): you just hook a chip to the sensory nerves leading to the brain. When you activate your holodeck you just shut off the real input and replace it with the computer images. In practice it is a little trickier of course. It would require cutting the nerve and attaching the chip to each individual cell. Something which is impossible with current technology.

The third thing you’d need is temporary paralysis. Though this may sound scary it is actually already build into our brains. It’s function is to prevent us from acting out our dreams and thus putting ourselves into dangerous situations. Cases are known in which people attack or have sex with their spouses in their sleep because of a lack of sleep paralysis. The sleep paralysis could easily be activated be tDCS, TMS or by implanting a chip and may even be the easiest to accomplish in our neural interface holodeck.

In conclusion I can say that if a holodeck based on the neural interface will become a reality it is still a long way off. Even if the technology was invented tomorrow to do it practically we’d still lack the knowledge of how the brain actually works to manipulate it so precisely. It sounds scary but would basically be an on demand dream machine. In the case of implants based on wireless technology hacking would be a real concern however.

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