MEG scanning out of the running?

[make tea / coffee now]

MEG scanning is a hot topic in brain / computer interfacing at the moment. On seeing the scan results, even people who don't know much about science realise that it offers something a lot better than normal EEG and electrodes stuck to the person's head.

I believe brain / computer interfacing is the way we should be looking to extend our lives. Those who understand the full potential of this transistion, not limited to lifespan extension, will recognise why I believe this. I feel that things like cryogenics aren't really in the spirit of life extension, merely life perservation. Cryogenics offers the general public a way to sit back and wait while others get on with all the hard work of trying to find a way to defrost them and regenerate their defective tissue masses. Saying this of coarse, if I have the money, I'll be signing up as well. But I view it purely as a safety measure rather than a truely effective method; I would carry on my brain / computer work even after being defrosted.

The problems involved with firstly making the connection and then finding a means of 'swapping' a consciousness between forms is immense and I have limited time to find a solution before I'm likely to die. I'm 21 at the moment, but decades isn't long with a problem this big and I worry it's not enough.

With the worry in mind, I began cluster researching numerous methods of brain / computer interfacing, MEG / EEG / Direct Connection etc for feasibility. Direct interfacing seems the most distance on first appearance, the best electrodes used for patients with critical conditions or experimental research work at the moment have about a hundred penetrating channels. It doesn't take a scientist to realise a hundred is quite short of the number of neurons in the brain, which is counted in billions.

MEG and EEG (including derivatives, i.e. HEG etc) can produce real world 'wow factor' data, like being able to control a wheelchair or 'Pong' paddle in a game without moving, that makes the none scientific interested in them. For immortalists, these technologies, MEG in particular, provide a possible means of saving, relocating or transformer consciousness.

Since I have the advantage over a physicist in that I know what I'm looking for, where it'll be and how I can find it, I decided to investigate the possibility that we can't already achieve a 'mind reading machine' for the lack of simply spending enough money on an individual unit, not bothering with the economics manufacture and market, only results. That, like these immortalist hope, the effect could be achieved by just building better and better MEG scanners.

After a lot of reading into the systems used in MEG scanners, like the superconducting quantum interference detectors, one of the things that becomes apparent is the scale of the request. The brain, even as a whole, emits a painfully small magnetic field that's easily demoted to background noise by something like the Earth's own magnetic field fluctuating slightly. You need hugely elaborate pickup designs (Gradiometers) and magnetic shielding (Superconducting) to get rid of most of the noise. This is something the SQUID developers are working on, to create a SQUID that ignores anything but localised fields.

A much more concerning problem is that of ultimate sensitivity. Moving a Pong paddle is not a complicated task, you could do it with just one signal, biasing the paddle to return to one side of the screen on release and using a single input to temporarily move it in the other direction a bit. I decided to push this out towards the limits that would be needed for the kind of brain / computer interfacing we'd like, wherein there's some hope of a brain being 'downloaded', that being a sensitivity high enough to read a single neuron depolarisation and an equipment build / result processing power accuracy high enough to locate that event's exact position in both space and time.

The initial results of my researching don't seem promising at all.

I'm aware of almost no one trying to push magnetic sensitivites out this far. Most SQUID research seems to be being targeted at applications in industry requiring higher than normal magnetic sensitivity but ultimately involving higher field strengths than those found in the brain; increasing the SQUID's rejection of ambient noise for instance. The level of sensitivity required for single neuron scanning puts the SQUID elements into the domain of prototype, one off physics equipment and perhaps beyond.

Present day MEG scanners scan 'brain tissue' acitivity for analysis of conditions like epilepsi. For this activity to show up on the scanner, somewhere between ten and a hundred thousand neurons need to depolarise pseudo-synchronously, far from single neuron sensitivity. What makes this worse is that SQUID devices count discrete units of flux, fluxons, and the quoted threshold for a SQUID is only one order of magnitude below today's 'brain activity', that is, it's self, ten or a hundred thousand times below what it really needs to be for detailed brain / computer transfers.

To put the expected level of sensitivity into perspective, a fridge magnet you might have in your Kitchen will be around 0.1 Teslas. The level of brain activity being scanning for now is on the order of tens or hundreds of femto Teslas, that's 10^-15 or ten million times lower than the field around a fridge magnet. The level required for sensing individual neuron depolarisations is closer to atto or zepto, 10^-18 to 10^-21, that's about a billionth of a billionth of a Tesla or less, possibly extending towards yocto Teslas for deeper tissue, 10^-24. As far as I can trust my own memory, the world's most accurate clocks wouldn't be capable of measuring units this small and time is the dimension we can most accurately measure at present.

The requirement placed on present day MEG is not just to improve it's performance a few multiples, but thousands of times over. A big request for a technology that's already pushing the boundaries in it's own design as well as that of the equipment used to support it; helium refrigerators for near absolute zero performance / noiseless power supplies and amplifiers for the output signal / shielding etc.

I've been discussing the feasibility of improving this sensitivity with a Dr of phyics, who happens to have experience with superconductors and SQUIDs. While he mentioned that he wasn't an expert on SQUID design, only that he uses them and understands superconductivity, he, like myself now, believes that attempting to design a MEG scanner with this degree of sensitivity is questionable.

The main problem MEG scanners have, aside from being swamped in magnetic noise, is that they're attempting to measure fields that are already weak, from distance. Magnetic fields decay rapidly over distance, moving just a few mm away can make the difference between it being registered or not.

SQUID detectors are superconducting devices, indeed, they must be for the effect they rely on to occur, and we do not possess room temperature superconductors. This means the devices must be positioned physically separated from the human head and cooled in a cryostat if one does not wish to simultaneously freeze the individual, ceasing any neural activity that was there to begin with. This has a benefit because the scanning is a totally passive affair, there's no need to expend time or money positioning, implanting, then removing and sterilising or disposing of and rebuying the field detectors before the next implantation.

Moving the detectors closer the individuals brain tissue may give MEG a helping hand towards individual neuron depolarisation sensitivity but it's still unlikely to be enough. This may also mean implanting the detectors, requiring body temperature superconductors, and doesn't take into account the fact that the detectors are physically quite large; although the SQUID element can be made quite small, the pickup coils can't, as making them smaller also decreases their efficacy, something MEG really doesn't need! Such detectors may even be probe like and carefully positioned within the tissue it's self, not just sitting on top of it.

The Dr I spoke to suggested making the pickup coil area bigger. This is an idea, but more coil area per channel also means fewer channels in the same total area, meaning lower spatial resolution. Making the field stronger isn't an option, since we can't 'power up' our brain tissue. Nore can we roll our brains out to make the scanning area bigger.

All these improvements might be enough, but they rely on seriously big developments; body temperature superconductors, pickup coils small enough to be implanted etc.

Then we have more problems. Humans being scanned will be alive and living humans have a tendancy to twitch or move ever so slightly from time to time. They also produce a strong, continuous vibration in the form of a heartbeat that's mechanically coupled to the brain tissue, via the excellent blood flow from the heart that supplies it. None of these are a major problem if you're looking for macro tissue activity, but to transfer data between two points you need to have some form of spatial and temporal lock between the two such that the transfer will be from a known point to a known point and at a known time index. If you're trying to move that data between individual neurons any movement, even on a micrometer scale, could be enough to corrupt the transfer. MEG scanner's can't 'lock onto' tissue and actively track it's movement. Theoretically they could, but remember that you'd be expecting it to track billions of separate targets that have the potential for growth and reorienting themselves morphologically.

Now we move on to one of the biggest problems. Lets assume that to be sure that we, the conscious being, isn't wiped out during the transfer we want to be able to communicate back and forth as the transfer takes place, to remain conscious and ensure continuity. MEG can't stimulate brain tissue. Magnetic fields have been shown to produce some form of result in brain tissue but at macro levels, entire half hemispheres of the brain, or at least very large fractions of them.

To focus a magnetic field down to a single neuron accuracy, especially over these distances, is beyond our ability. To focus a field to simultaneously stimulate billions of neurons as individual units is an unbelievably big request. Also remember that this field will function like a gamma knife would, with the potential for 'side stimulations' as the field gets to the point in the volume it's targeted at. Now this stimulating field, something that produces lots of noisey magnetic field modulation, and MEG scanner, something that is incredibly sensitive to magnetic fields, need to put in the same space as each other.

All theoretically possible. But, I believe, painfully distant.

Unlike a lot of scientists, immortalists need to be very aware of timescales. Something may be theoretically possible, but if it's not realistically possible within their lifespan then it's not really an option.

It's for these reasons that I would suggest MEG is a less than great option for other immortalists looking at brain / computer interface technologies to place too much hope on for the near future. I would, of coarse, actively encourage you to keep up to date with what is happening with SQUIDs etc and to make an attempt to learn how they work, I myself am ready to reconsider MEG if I see a substantial development emerge. But expecting the scanners to go from controlling Pong games to downloading a consciousness is, while theoretically possible, a remote option at present.

A number of similar problems occur for EEG and there is no electric field sensitive variant of the SQUID. Although, if such a device were to appear, it may proove interesting. Neurons depolarise at voltages that are high enough for a normal audio amplifier's input to pick them up if there were a direct connection between the two; a depolarisation occurs at tens of millivolts. However, the depolarisation involves only minimal amounts of current, a few thousand ions or nano amps. Neurons would appear to be 'high voltage / low current' devices. Magnetic field strength is set by current, if the current of a neuron is low, it's magnetic flux creating ability will also be low. Electric fields strength is set by voltage. Thusly, if the neurons depolarise at substantially higher voltages than they allow current to flow through them, and we have an electric field detector as sensitive as a SQUID is with regards to magnetic fields, capacitively coupling to them would be appear to present a more positive option.

Personally, I believe that direct connection is the best route to follow. Once a direct connection is made everything else will be much easier. Detecting and measuring depolarisations will be a joke it'll be so simple! Off the shelf IC's can achieve nano volt noise performance at their input, whereas neurons depolarise at tens of millivolts. Bidirectional communication would also be easier since there would be fixed connections from each neuron to each interface address, no need to actively track each neuron as it moves with vibration. Lastly, this is an area that has a lot of drive already behind it, all be it indirectly, from the electronics industry, providing it with things like microscopic amplifiers with excellent noise performance, and ever increasing data storage and handling capacities via holographic drives and solid state semiconductor blue lasers.

These are just some thoughts and conclusions I've been thinking over for the last few weeks whilst I've been putting in ten or so hours of reading a day towards answering this. I thought it would be best to summarise some of these here for other immortalists interested in brain / computing interfacing to read before they 'waste' time having to reread the information in it's long form and piece it together for themselves.

My reference for a successful neural interface is one that is capable of addressing each individual neuron of the brain tissue simultaneously, although fractions may proove to be perfectly acceptable given that large percentages of the brain tissue seem to be below their maximum potential for activity a lot of the time, and supplying a pathway for bidirectional communication between those neurons.

Any thoughts, questions, ideas, discussion?

Hugs and kisses, [thumb]
John

Edited by johnuk, 17 December 2005 - 04:35 PM.

As I already pointed out in another thread, your basic paradigm is flawed. You cannot capture the contents of a human mind by just monitoring what the brain is doing during a limited period of time any more than you can download the contents of a computer from the EMF generated by the computer monitor.

Also, I advise you to lookup the definition of "cryogenics" before making comments about the field. It is not what you think in more ways than one.

---BrianW

As I already pointed out in another thread, your basic paradigm is flawed.  You cannot capture the contents of a human mind by just monitoring what the brain is doing during a limited period of time any more than you can download the contents of a computer from the EMF generated by the computer monitor.

I understand that, and actually made a similar point about the level of brain activity somewhere in that, or another, post; that only a percentage of our brain is active and made an analogy to a hard drive only having a few percent active at any one time but no one would like the remaining, temporarily unactive percentage wiped. However, I still don't believe you need to actually pull apart each synapse molecule by molecule.

To understand the logic contained within something, you need to observe input and output to calculate what the mutating / transforming factor was likely to have been. Since the 'input' to our mind is so qualative and difficult for us to control precisely, merely scanning,observing the output, won't be enough. However, if you were to equip the scanning apparatus with a way to stimulate the tissue at the same resolution it's scanning, neuron by neuron, the scanner could be made to 'probe' the neurons into activity. Returning to the hard drive analogy, you'd be forcing blocks of memory into activity rather than just waiting for them to reactivate at some date in the future. You'd also be forcing them with a known quantity, so you'd be able to calculate what had changed between the probe and the observation.

This is why I think direct interfacing is probably the best idea, since it also provides an easy means to both observe and probe the tissue. MEG, and all the other none contact methods, lack such an ability and would need equally specialised research doing to provide them with this as is still needed to get them to single neuron resolution scanning.

I think a single neuron MEG scanner would be useful, perhaps not for brain / computer interfacing, but as tool for simply investigating the brain for now. I'm quite sure MEG will continue to develop over the next few years as most people don't really care about immortality or consciousness swaps by brain / computer interfacing and would prefer to continue with MEG as a clinical diagnosis tool. Almost no one, bar the brain / computer guys etc, seems to have considered the idea that by attacking root problems we can alleviate the branching problems; if you don't have a heart, you can't die of a heart attack, no lungs, no lung failure.

The 'EMF' generated by our brains doesn't equate the EMF from a computer monitor because the field is measured around our brain tissue and not any of it's outputs. This means that the field being measured is being produced by the CPU and RAM / HDD. Sensitive computer servers are already being physically hidden away in locked vaults underground to keep them safe from attack. The power supplies to these computer is also filtered to prevent attempts that have been made to listen in to what the computer is doing through the power supply. If someone then developed a tool that could view every individual transistor's contribution to the EMF around the CPU, I'm sure you wouldn't disagree that the chances of them also being able to develop some software to translate those EMF results into a form allowing them to observe what the CPU was doing, bit by bit, wouldn't be too remote. A direct neural connection would be synonymous with connecting 'tap' wires to every single transistor in the CPU and every unit in the memory. You wouldn't need to know what the charge carriers were doing in the transistors to see the signal they were producing. Even though we wouldn't need to, if so desired we could deduce what the charge carriers were likely doing because we know how they produce signals in transistors. Just as, I think, you don't need to know what the neurotransmitters themselves are doing, only to oberserve and input go into a junction and an output emerge.

Making one probe and observing one output almost certainly won't be enough to calculate the precise series of mutations that must be occuring between the two because there may be hundreds or more neurons between that particular probe and observation point. But when you increase the number of probe and oberserve points to billions you'll start getting an extremely detailed collection of results and virtually all of them will have interlinking factors somewhere; neuron xxx fires and then three others, xxx, xxx and xxx fire immediately afterwards. There's no way a human could link all of that together in any reasonable time scale, but computers are great at this kind of thing. The only thing that would be strange would be if you were awake for the probing process since you could at least expect to experience huge quantities of your memories being relived with no apparent reason. The biggest problem I can see for this idea is that you'd want to do the probing and observing quickly before the individual started growing new memories as a result of the process it's self, needing more tap points to prove and observe.

Also, I advise you to lookup the definition of "cryogenics" before making comments about the field.  It is not what you think in more ways than one.

I know that it should really be cryonics, but I do a lot of reading and one thing that annoys me is when people start making up new words for things that don't really need them, that I then have to try to squeeze into my memory alongside things that are more important, like how SQUIDs work and all the associated stuff to do with superconduction and cryogenic refridgeration.

To me, and most dictionaries I believe, cryogenics is anything involving low / ultra low temperature work. Freezing bits of meat that happen to resemble people doesn't really warrant much memory space from me. Cryonics is a flash word used by the cryogenic storage companies to make it sound cool. Pun not intended, but I still like it! [lol]

I've even played around with nitrogen myself and seen what happens to a banana on warming up from cryogenic temperatures, babyfood looks like the chewy alternative by comparison. Not to say cryogenics won't work, but I'm counting on it only as a backup. It relies on technology that's more problematic than preventing aging in the first place, that being rewinding all the damage caused in the delay between legal death and getting the body into the cryogen (bacteria, radicals and all the other factors that are normally kept under check to prevent tissue damage occurring are allowed to do whatever they like for hours or days), the cryogenic feezing process it's self (crystalisation, but I already know... vitrification, perhaps one of the easier problems to fix), the pathology of whatever caused the person to 'die' (e.g. remove all the cancer from them) and then the damage they accumulated over most of their life that lead to the pathology being expressed (Aubrey De Grey); no one wants to be revived only to be old and 'die' again within a few years. Big, big challenge!

Don't get the wrong idea, I don't think 'scanning' minds out with a MEG scanner has a very good chance of working (I wouldn't go as far as saying it's totally impossible as I'd like a solid answer about what happens to our continuity of consciousness when we go to sleep first), and I'll probably end up having a liquid nitrogen bath as well.

In fact, the point of this thread was to try to discourage people from standing still to long, hoping for a leviathon MEG scanner to save them.

Best wishes,
John

Edited by johnuk, 18 December 2005 - 12:18 PM.