Lights and Brains: Injectible LED's Interact with Brain Cells

The quest to put computers in the brain has just come a step closer.  Tiny LED lights have been implanted deep in the brains of rodents.  The LEDs themselves are the size of individual neurons.  They are packaged with other tiny sensors into an ultrathin, flexible device.  The whole device is small enough to be implanted using a needle that positions the device at precise sites deep in the brain. 

Once implanted, the device communicates directly with the brain at the level of cells.  It communicates wirelessly with a module mounted above the rodent’s head, one small enough not to interfere with activity and removable when not in use.  The device itself is completely contained within the brain where it was implanted without any damage to surrounding cells.  Signals sent through the device stimulate genetically modified brain cells, signaling for example for the release of neurotransmitters such as dopamine. 

Photo Credit: MicroLED device next to a human finger.  Image courtesy of University of Illinois-Urbana Champaign and Washington University-St. Louis.

 

"These materials and device structures open up new ways to integrate semiconductor components directly into the brain," said team co-leader John A. Rogers according to a press release from the University of Illinois.  "More generally, the ideas establish a paradigm for delivering sophisticated forms of electronics into the body: ultra-miniaturized devices that are injected into and provide direct interaction with the depths of the tissue."

The device itself is a feat of engineering requiring the effort of an international team based in China, Korea, and at multiple centers across the US.  By miniaturizing the device to the cellular scale and by creating a totally wireless interface, researchers overcame several challenges at once.  For example, larger implantable devices always run the risk of creating scars or lesions in the brain, which may cause serious problems.   "One of the big issues with implanting something into the brain is the potential damage it can cause," team co-leader Michael Bruchas said. "These devices are specifically designed to minimize those problems, and they are much more effective than traditional approaches."

In addition, because this device communicates and receives its power wirelessly, there are no wires or optical fibers passing from the brain to the outside world.  Previous devices were larger and nonflexible. They were implanted only on the surface of brain structures, but this new device is implantable deep within those structures and able to interact with units as small as a single cell.

Along with the LED lights, the device includes temperature and light sensors, microscale heaters, and electrodes that can stimulate and receive brain electrical activity.  Power to the device is provided wirelessly through a radio frequency system. 

It is impossible to predict the future of efforts to connect brains and computers. This work obviously represents a significant advance toward that end.  "These cellular-scale, injectable devices represent frontier technologies with potentially broad implications," Rogers said. Being able to monitor and trigger the brain of living animals at the cellular level is likely to become a profoundly valuable tool for research.  Medical research, too, is also likely to be affected, not just in responding to patients with paralysis but also in research and perhaps even therapy in other diseases involving the brain or other organs, where these devices are also implantable. 

Some, of course, will speculate about even wider implications for this technology.  Will it open the way to control people by controling their brains?  Perhaps.  Will it open the way for our brains to communicate with computers and the internet?  There is little doubt that this step will inspire more work along those lines. 

This article is entitled "Injectable, Cellular-Scale Optoelectronics with Applications for Wireless Optogenetics" and is published in the April 12, 2012 issue of the journal Science, a publication of the American Association for the Advancement of Science. 

The Two Million Year Question

Careful studies of 2-million year old human-like fossils just published in the April 12, 2012 issue of Science raise more questions than they answer.

These papers provide highly detailed information about the teeth, rib cage, hands, and feet of this strange relative, known to scientists as Australopithecus sediba.  But we still do not know the answer to the biggest question of all.  How does sediba fit in the human family tree?  Is sediba a direct human ancestor?  If not, why are they so similar to us in some respects?

Photo Credit: The reconstructed skull and mandible of Australopithecus sediba.Reconstruction by Peter Schmid, Photo by Lee R. Berger. Image courtesy of Lee R. Berger and the University of the Witwatersrand.

The teeth are mostly like those of Australopithecus africanus but also quite a bit like the earliest examples of the genus Homo.  That is surprising.  For some experts, it calls into question the standard view that Homo evolved from Australopithecus afarensis, most commonly known as “Lucy.” 

The new analysis suggests an evolutionary pathway from africanus to sediba to Homo.  In that case, Lucy is a relative but not an ancestor.  Sediba is. 

Not so fast, others insist.  The first examples of Homo may go back to 2.3 million years ago, long before sediba appears at just under two million years ago.  Lucy and her afarensis kin lived much earlier, enough to be ancestral to Homo. 

Based on what we know now, the debate will continue because the facts just do not line up neatly or offer a simple story.  "Our study provides further evidence that sediba is indeed a very close relative of early humans, but we can't definitively determine its position relative to africanus,” study co-author Debbie Guatelli-Steinberg said according to a release from Ohio State University.

What these studies do provide is a remarkably complete picture of what early human-like ancestors look like.  They also provide another surprise.  Despite having a foot with a narrow heel, similar to chimpanzees, sediba definitely walked upright, maybe even using a somewhat awkward never known before to scientists.  They were clearly not knuckle-walkers, like the apes, but they were not nearly as graceful as the humans who followed.  It seems they walked upright differently.  

For now, what all this suggests is that the story of our deep ancestry is more complex than we usually imagine.  Straight ancestral lines are hard to draw.  More finds may help sort things out.  But they may also add new complexity.  The way it looks, multiple forms of early human life may have existed at once.  They differed slightly from each other and also in the degree to which they resemble us.  That makes it very hard to sort out the lineages.  

Is sediba a direct human ancestors?  Yes, at least according Lee Berger, who discovered sediba in a pit in northern South Africa in 2008.  Most experts, however, argue no, mainly the dates are out of line.  What difference does it make?  Perhaps the biggest significance of this debate is to show us that the more we know, the more we see a complex picture of multiple species and perhaps interweaving lineages, making it all the more remarkable that we are here at all. 

This research is published as a set of six research reports in the April 12, 2012 issue of the journal Science, a publication of the American Association for the Advancement of Science.