Optogenetics: the key to our cyborg future?

Paul Raven @ 23-10-2009

neuronsThere’s a lengthy but interesting piece up over at Wired about the relatively young discipline of optogenetics – the science of isolating and communicating with specific types of neuron using light. The discovery of the process is an interesting story in its own right, but the really futurismic bit is the implication tucked into the final few paragraphs:

Optogenetics has amazing potential, not just for sending information into the brain but also for extracting it. And it turns out that Tsien’s Nobel-winning work — the research he took up when he abandoned the hunt for channelrhodopsin — is the key to doing this. By injecting mice neurons with yet another gene, one that makes cells glow green when they fire, researchers are monitoring neural activity through the same fiber-optic cable that delivers the light. The cable becomes a lens. It makes it possible to “write” to an area of the brain and “read” from it at the same time: two-way traffic.

Why is two-way traffic a big deal? Existing neural technologies are strictly one-way. Motor implants let paralyzed people operate computers and physical objects but are incapable of giving feedback to the brain. They are output-only devices. Conversely, cochlear implants for the deaf are input-only. They send data to the auditory nerve but have no way of picking up the brain’s response to the ear to modulate sound.

No matter how good they get, one-way prostheses can’t close the loop. In theory, two-way optogenetic traffic could lead to human-machine fusions in which the brain truly interacts with the machine, rather than only giving or only accepting orders. It could be used, for instance, to let the brain send movement commands to a prosthetic arm; in return, the arm’s sensors would gather information and send it back.

Science fiction has been talking about the brain-machine interface for decades, but usually in terms of splicing the hardware into the nervous sytem in much the same way as connecting up a regular electronic circuit, and with little experimental evidence for its viability. As Chorost points out in the Wired piece, we’re not going to see commercially available optogenetic interfaces for some time yet, but this proof-of-concept work suggests it really is only a matter of time before we do. [image by LoreleiRanveig]

Light in a bottle

Tom James @ 29-07-2009

microresonatorScientists have developed a technique for confining light within a bottle:

Similar to the motion of a charged particle stored in a magnetic bottle, i.e., a particular spatially varying magnetic field, the light oscillates back and forth along the fiber between two turning points. For this reason, this novel type of microresonator realized by the physicists in Mainz is referred to as a bottle resonator. Tuning the bottle resonator to a specific optical frequency can be accomplished by simply pulling both ends of the supporting glass fiber. The resulting mechanical tension changes the refractive index of the glass, so that depending on the tension, the round-trip of the light is lengthened or shortened.

This could lead to the creation of a glass fibre quantum interface between light and matter, which in turn is an important component of hypothetical quantum computers and quantum communication systems.

[from Physorg][image from Physorg]

“Superlenses” could lead to movies of molecules

Tom Marcinko @ 11-06-2009

neonFor a long time physicists thought it was impossible to see anything smaller than about half the wavelength of light.

That’s true if you look at the propagating component of light waves. But light also records smaller sub-wavelength details in its evanescent components, which do not propagate. At least not usually. What [John] Pendry showed [about 10 years ago] was that evanescent components can propagate in a material with a negative refractive index, and he pointed out that a thin film of silver ought to have just the right properties.

Since then, the race has been on to build superlenses. In 2005, Nicolas Fang at the University of Illinois at Urbana-Champaign created one that could record details as small as one-sixth of a wavelength. That was a significant improvement over the diffraction limit, but why not better?

Fang and company recently achieved resolution of only one-twelfth the wavelength of light. The theoretical limit is now pegged at one-twentieth a wavelength, which should be small enough to watch molecules in motion.

The impact of such “transparency” on the micro level opens up fertile realm for speculation: Surely drug designers, among others, are going to want superlenses of their own.

[Story: Technology Review physics arXiv blog; thanks for the tip, dpodolsky; London neon sculpture photo: clry2]

Quantum superposition breakthrough

Tom James @ 29-05-2009

theory_actualA rich seam of technological and science-fictional ideas seem ready to be mined with the development of the first light trap that can simultaneously store different numbers of photons:

“These superposition states are a fundamental concept in quantum mechanics, but this is the first time they have been controllably created with light,” Cleland said. Martinis added, “This experiment can be thought of as a quantum digital-to-analog converter.” As digital-to-analog converters are key components in classical communication devices (for example, producing the sound waveforms in cell phones), this experiment might enable more advanced communication protocols for the transmission of quantum information.

The research is funded by IARPA. Intelligence services are understandably keen to learn more about the potential for quantum computers to break conventionally encrypted communications.

[image and story from Physorg]

A brief word on a new supermaterial

Tom James @ 05-05-2009

graphene-transistorGraphene: a material consisting of a sheet of carbon atoms one atom thick. Graphene was first identified only a few years ago, and has since been proferred for all sorts of uses, including ultracapacitors, spintronics, and now as a light source:

Microchips is just one of the material’s potential applications. Because of its single-atom thickness, pure graphene is transparent, and can be used to make transparent electrodes for light-based applications such as light-emitting diodes (LEDs) or improved solar cells.

It is also apparently very strong:

The mobility of electrons in graphene — a measure of how easily electrons can flow within it — is by far the highest of any known material. So is its strength, which is, pound for pound, 200 times that of steel.

The problem is to find a way to mass-manufacture it:

The trick that enabled the first demonstrations of the existence of graphene as a real separate material came when researchers at the University of Manchester applied sticky tape to a block of graphite and then carefully peeled off tiny fragments of graphene and placed them on the smooth surface of another material.

“They don’t care if they go to a lot of effort to make five tiny pieces, they can study those for years.” But when it comes to possible commercial applications, it’s essential to find ways of producing the material in greater quantities.

[from Physorg][image from Physorg]

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