Fiber Optic Neural Interfaces: Tests to Begin Soon

Popular Science [1] has reported a tidbit of information: Marc Christensen’s team at SMU is supposed to start testing if they can stimulate a rat’s leg with optical fibers.

This is the same DARPA-funded project I mentioned last September in my article “Softer, Better, Faster, Stronger” [2]. DARPA held a related “Reliable Neural Interface Technology (RE-NET)” workshop back in 2009 [3]:

A well-meaning motor prosthesis with even 90% reliability, such as a prosthetic leg that fails once every 10 steps, would quickly be traded for a less capable but more reliable alternative (e.g., a wheelchair). The functionality of any viable prostheses using recorded neural signals must be maintained while the patient is engaged in or has their attention directed to unrelated activities (e.g., moving, talking, eating, etc.). Since the neural-prosthesis-research community has yet to demonstrate the control of even a simple 1-bit switch with a long-term high level of speed and reliability, the success of more ambitious goals (e.g., artificial limbs) are placed in doubt.

DARPA is interested in identifying the specific fundamental challenges preventing clinical deployment of Reliable Neural Technology (RE-NET), where new agency funding might be able to advance neural-interface technology, thus facilitating its great potential to enhance the recovery of our injured servicemembers and assist them in returning to active duty.


Some of the challenges listed for the optical (neurophotonic sensing) approach are [4][5]:

  • Transduce action potential into optically measurable quantity
  • Modes: ionic concentration / flux vs. electromagnetic field
  • Field Overlap
  • Can’t go straight from voltage (indirect detection)
  • Sensitivity, Parallelism
  • Packaging, Size
  • Untested
  • “What is the minimum level of control-signal information required to recover a range of activities of daily living in both military and civilian situations?”
  • “Need a method for characterizing tissue near implant to better understand long term degradation.”

Some of those challenges probably apply to all forms of neuro sensing. Likewise, the metrics for neurophotonic interfaces–resolution, signal-to-noise ratio, and density–probably apply to other methods as well.

The Need for Better Neural Interfaces

Maybe the neurophotonic approach won’t work in the end, or it will only work in combination with another method. Whatever the case, a lot of money should be put into this kind of project. We are in desperate need for more advanced neural interfaces. As Dr. Principe of the University of Florida writes [6]:

Just Picture yourself being blindfolded in a noisy and cluttered night club that you need to navigate by receiving a voice command once a second…And you will understand the problem faced by engineers designing a BMI [Brain Machine Interface].

Present systems are signal translators and will not be the blue print for clinical applications. Current decoding methods use kinematic training signals – not available in the paralyzed. I/O models cannot contend with new environments without retraining. BMIs should not be simply a passive decoder – incorporate cognitive abilities of the user.

Interfaces to the nervous systems are the key enablers for all of future prosthetics–and of course other exotic devices that don’t even exist yet. Without overcoming this interface hurdle, we’ll be stuck in the stone age of prosthetics and nervous system repair.

[1] M. Peck, “Talk To The Hand: A New Interface For Bionic Limbs,” Popular Science, Feb 24, 2011.
[3] J.W. Judy & M.B. Wolfson, RE-NET website.
[2] “Softer, Better, Faster, Stronger: The Coming of Soft Cybernetics,” H+ Magazine, Sept 21, 2010.
[4] M.P. Christensen, “Neuro-photonic Sensing: Possibilities & Directions”, DARPA RE-NET Workshop, Nov 19, 2009.
[5] Optical Breakout Session Report, DARPA RE-NET Workshop, Nov 20, 2009.
[6] J.C. Principe, “Architectures for Brain-Machine Interfaces,” DARPA RE-NET Workshop, Nov 19, 2009.

Image Credits:
[1] Rajeev Doshi, PopSci
[2] DARPA / CIPhER via Physorg
[3] scan of book cover, art by John Berkey


  1. The danger with neural interfaces is not in all the good they can do – this is obvious. The dangers are in the inherent negative potential abuses of power that 100% spatio-temporal read-write interfaces are absolutely capable of causing. With wireless capacity – such interfaces pose a huge moral, legal and ethical set of problems because they offer
    “quick fixes” to social problems that are simply too inhumane for an equitable, free and civil society to endorse, yet too “appealing” for populist support to not want. CRIME for example. Certain crimes are either themselves classifiable as disorders or associated with them. With wireless interfaces and the proper automated software architecture, these disorders could be treated, while providing a lower cost relative to imprisonment, and a lower risk of recidivism for the criminal offender. These reasons give society the excuse to “jump the gun” and begin using COMPULSORY IMPLANTATION as part of the criminal justice system and/or the medical system (as schizophrenics, for example, could also be helped in a much cheaper more effective fashion with an implant than a psych ward). I do not have a problem with neural interfaces and serverside software helping individuals with psychological problems, but I firmly believe, with all my heart, that this can NEVER BE DONE IN A COMPULSORY OR COERCED MANNER. It must always be CONSENSUAL if we are to call ourselves a free society with equitable justice. There are a myriad of reasons this would introduce inequitable justice into the criminal justice system AND the medical system. For example: no treatment is UNIVERSALLY effective, and those for whom the treatment would not help would either be screened out of its benefits, receiving inequitable justice or treatment, or they would be subjected to it and only find out too late that it doesn’t work for them… The worst case scenario is also very very bad – collateral damage from aversive behavior modification driving a “patient” insane to the point where he kills innocents from the inescapable pain in his head (far worse than the pain of physical imprisonment.) Behavior modification, just like all of the potential criminal or medical psychological uses of wireless neural interface technology, is inhumane unless with ongoing informed consent, inequitable unless non-coerced and with ongoing informed consent, is a public danger potentially mounting to a national security threat unless non-coerced and with ongoing informed consent, is unconstitutional due to privacy issues of tracking and 24/7 neural surveillace, is unconstitutional due to cruel and unusual punishment unless non-coerced and with ongoing informed consent, and lastly, fits the definition of FASCISM if compulsory, and thus is a trojan horse for the degradation of a FREE AMERICA and antithetical to PROGRESS, sacrificing humanity, ethics, rights, and equitable justice and medicine for the promise of efficiency, efficacy and cost-savings. WE CANNOT BE SO SHORT-SIGHTED AS A FREE DEMOCRACY AS TO ALLOW COMPULSORY TORTURE INTO OUR SOCIETY BASED ON UTILITARIAN NOTIONS – I REMIND YOU THAT MUSSOLINI “MADE THE TRAINS RUN ON TIME” – FASCISM ALWAYS BEGINS WITH UTILITARIANISM AND POPULISM, AND OUR REPRESENTATIVES MUST CURB SUCH A PUBLIC ZEAL FOR RESULTS AT THE COST OF OUR CORE DEMOCRATIC STRUCTURE OF GOVERNANCE.

  2. Let’s cut through the crap. DARPA wants to build an elite unit of internet-connected, genetically modified, exoskeleton-enhanced, drugged up warriors to do the US army’s dirty work. Public sources point heavily toward this motivation. The notion that they are looking to dump loads of dollars on helping people is a complete and transparent fabrication.

    • Anon, DARPA does use the products of its research for military uses and its no secret or surpise to anyone. However their technological breakthroughs do end up helping people. For example, ARPA (DARPA’s predecessor) was essentially responsible for the creation of the internet (it was called ARPANET before it was called the WWW). So you, at the very moment you read this article and responded were benefiting from DARPA’s work. In fact a staggering number of breakthroughs come from them.

      Now I do agree its a shame that the notion of pushing the boundaries of technological progress should be aimed primarily for military use. Thankfully though, we have the NIH and a few good companies doing their own research too.

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