lördag 5 maj 2012

Artificial synapses and brain?

It's probably still going to be a while before autonomous, self-aware androids are wandering amongst us. That scenario has come a little closer to reality, however, with researchers from the University of Southern California having created a functioning synapse circuit using carbon nanotubes. An artificial version of the connections that allow electrical impulses to pass between neurons in our brains, the circuit could someday be one component of a synthetic brain.
The USC Viterbi School of Engineering team was led by Professors Alice Parker and Chongwu Zhou. Parker has been looking into the feasibility of creating a synthetic brain for the past five years, as part of the BioRC Biomimetic Real-Time Cortex project.
The circuit itself consists of highly-aligned carbon nanotubes that are grown on a quartz wafer, then transferred to a silicon substrate. It mimics an actual synapse insofar as the waveforms that are sent to it, and then successfully output from it, resemble biological waveforms in shape, relative amplitudes and durations. In other words, it can take in the type of impulses generated by real neurons, and send them on in a form that could be further processed by other neurons - it can even vary the strength of those impulses, much as real synapses do in a biological process that is thought to facilitate learning.
"This is a necessary first step in the process," said Parker. "We wanted to answer the question: Can you build a circuit that would act like a neuron? The next step is even more complex. How can we build structures out of these circuits that mimic the neuron, and eventually the function of the brain?"
While Parker stated that synthetic brains are probably still decades away, she believes that the technology could ultimately be used in prosthetic nanotechnology for treating traumatic brain injuries, or for designing intelligent systems that could be used to make cars safer, among other applications.
These nanotubes are a billionth of a meter in diameter, so the transistors are quite small. The chance for lower power operation than conventional electronics is certainly possible. This simple synapse is only a single transistor but it would take more transistors to have variability in neurotransmitter release and reuptake, and receptor concentration, like our conventional synapses. And while we implement mechanisms as fast as the neuroscientists report their understanding, there are so many open questions, which makes all of this very exciting and very much a small step towards an enormous goal. We're working on memristors, variability and other issues you mention, as well. However, implementing each mechanism or new technology in the laboratory takes a significant investment in time and energy, so achieving synaptic plasticity, for example, the next obvious step, is months away. comment Alice Parker - May 4, 2011  From Researchers create artificial synapses.

5 kommentarer:

  1. Very Interesting Ulla,

    I think this would result in more like a TGD environment a sort of computer which could be an alternative to our ideas of simple computation.

    I imagine such a device would transmit, which is odd for an experiment to by our real synapses and nerves would suggest ESP

    The PeSla

    SvaraRadera
  2. The main thing is the nanotubes, I think. They are very important, see the earlier posting. And plasmodesmatas, gap junctions, which are meridians, collagen, or anatomical trains. They are the 'enclosed environment'-space making the dance, but where is the dancer.

    SvaraRadera
  3. I addressed these issues somewhat in the Omnium of Creative Intelligence next post- it like with Matti looks again at time and so on, and our hot local blogger topics here of intention and time- or your posting before here on possible other principles of entropy or organization.

    Where is the dancer? Well, after sleeping on my surprisingly long post one principle or focus comes to mind- that it is in the surface of the tubes (perhaps their 9 strands, or with any nerves such surfaces (but who dances there?) these being paths of an infinity of wormhole mouths in a tube, and of even smaller subsets of things as Matti is also considering in this wider view. Well, let us keep looking :-)

    The PeSla

    SvaraRadera
  4. The dancer sometimes use local measurement, sometimes longdistance measurement, so... s/he cannot be at the surface of the tubes. They are just tools for connection? It seems more s/he is non-local, spread out over a bigger net (stochastic resonance then say s/he may be in the environment, outside the body. So Self is a learned thing, essential though for the organization? Or immune system, as seen in females chosing partners. They go after the smell of antiHLA groups.

    SvaraRadera
  5. Remote-controlled genes trigger insulin production http://nextbigfuture.com/2012/05/remote-controlled-genes-trigger-insulin.html

    http://www.nature.com/news/remote-controlled-genes-trigger-insulin-production-1.10585

    Nanoparticles heated by radio waves switch on genes in mice Researchers have remotely activated genes inside living animals, a proof of concept that could one day lead to medical procedures in which patients’ genes are triggered on demand. The work, in which a team used radio waves to switch on engineered insulin-producing genes in mice, is published today in Science 1 . Jeffrey Friedman, a molecular geneticist at the Rockefeller University in New York and lead author of the study, says that in the short term, the results will lead to better tools to allow scientists to manipulate cells non-invasively. But with refinement, he thinks, clinical applications could also be possible. Friedman and his colleagues coated iron oxide nanoparticles with antibodies that bind to a modified version of the temperature-sensitive ion channel TRPV1, which sits on the surface of cells. [activated by capsaicin, temp, pH (proton), voltage, lipids, endocannabinoids and delivering pain + nociceptive] They injected these particles into tumours grown under the skins of mice, then used the magnetic field generated by a device similar to a miniature magnetic-resonance-imaging machine to heat the nanoparticles with low-frequency radio waves. In turn, the nanoparticles heated the ion channel to its activation temperature of 42 °C. Opening the channel allowed calcium to flow into cells, triggering secondary signals that switched on an engineered calcium-sensitive gene that produces insulin. After 30 minutes of radio-wave exposure, the mice's insulin levels had increased and their blood sugar levels had dropped. Radio stars “The great thing about this system is that radio-wave heating can penetrate deep tissue, and TRPV1 can focus that stimulus very locally to just where you have the nanoparticles,” says David Julius, a physiologist who studies TRPV1 at the University of California, San Francisco. Friedman says that his team did not develop the method as a way of managing diabetes; insulin and blood sugar levels simply provide convenient physiological readouts for checking that the remote control is working. “There are many good treatments for diabetes that are much simpler,” he says. However, the system could potentially be engineered to produce proteins to treat other conditions. In control experiments, the researchers showed that the radio waves heated only cells that contained nanoparticles, and the heat neither killed the specialized cells nor spread to neighbouring, unmodified ones. “Magnetic fields are a good way to develop enough energy without doing harm,” says Arnd Pralle, a biophysicist at the State University of New York at Buffalo, who has worked on stimulating neurons using nanoparticles heated by radio waves 2 . However, he says, more research is needed to characterize fully how the nanoparticles absorb, retain and distribute heat. Genetic therapy The researchers also experimented with cultured cells genetically engineered to make their own nanoparticles, and found that they could stimulate a weaker insulin secretion in these cells, too. “What I found most novel about this is there’s no need for any chemicals or small molecules to be administered,” says Ed Boyden, who helped to pioneer a method of using fibre optics to control neural activity with light 3 . Friedman's current method is not practical for use in the clinic because it is not ethical to grow tumours in humans, so the researchers are planning to test alternative delivery systems for the nanoparticles.

    See picture of the ion channel. 6 subunit transmembrane proteins. Phosphorylation of TRPV1 by three different kinases controls TRPV1 activity by means of an intricate balance between phosphorylation and dephosphorylation of this channel. Hydrophobic pore. http://www.ncbi.nlm.nih.gov/books/NBK5260/

    SvaraRadera