Nora D. Volkow, Dardo Tomasi, Gene-Jack Wang, Paul Vaska, Joanna S. Fowler, Frank Telang, Dave Alexoff, Jean Logan, Christopher Wong. Effects of Cell Phone Radiofrequency Signal Exposure on Brain Glucose Metabolism. JAMA. 2011;305(8):808-813.

Summary in NYtimes: Cellphone Use Tied to Brain Changes

In motor cortex, ultrasound-stimulated neuronal activity was sufficient to evoke motor behaviors. Deeper in subcortical circuits, we used targeted transcranial ultrasound to stimulate neuronal activity and synchronous oscillations in the intact hippocampus. We found that ultrasound triggers TTX-sensitive neuronal activity in the absence of a rise in brain temperature (<0.01°C). Here, we also report that transcranial pulsed ultrasound for intact brain circuit stimulation has a lateral spatial resolution of approximately 2 mm and does not require exogenous factors or surgical invasion.

Nature sent me a press release about this today and it seemed like it might be of interest to ND readers. There is also a related commentary in the journal this week.

The conference sessions will cover several key areas in the neuroprosthetic development, such as deep brain stimulation for treatment of Parkinson’s disease and epilepsy, devices for restoring hearing and overcoming muscle paralysis, microelectrode biocompatibility, and novel microelectrode technologies. For detailed conference program and registration information, please visit http://www.bsrc.nctu.edu.tw/ICND/.

The concept that the brain holds maps of the surface of the body in the primary sensory and motor cortex is a fascinating but well known fact to the field of neuroscience since the early work of Wilder Penfield. What is less broadly appreciated is the concept of “peripersonal space”. A new book by Sandra and Matthew Blakeslee describes peripersonal space in the following way:

The maps that encode your physical body are connected directly, immediately, personally to a map of every point in that space and also map out your potential to perform actions in that space. Your self does not end where your flesh ends, but suffuses and blends with the world, including other beings. [...] Your brain also faithfully maps the space beyond your body when you enter it using tools. Take hold of a long stick and tap it on the ground. As far as your brain is concerned, your hand now extends to the tip of that stick. [...] Moreover, this annexed peripersonal space is not static, like an aura. It is elastic. [...] It morphs every time you put on or take off clothes, wear skis or scuba gear, or wield any tool. [...] When you eat with a knife and fork, your peripersonal space grows to envelop them. Brain cells that normally represent space no farther out than your fingertips expand their fields of awareness outward, along the length of each utensil, making them part of you.

What I appreciate about this, besides the stretchy comic book characters that it makes me think about, is that it provides a powerful perspective to begin piecing together a mass of disparate neuroscience data, which the Blakeslee’s capitalize on.

You’ll recognize the name Sandra Blakeslee from her co-authorship with Jeff Hawkins in On Intelligence and with V.S. Ramachandran in Phantoms in the Brain. This new book continues in the spirit of illustrating the broader significance of surprising findings in neuroscience. It covers a lot of recent neuroscience research, including mirror neurons, place cells and grid cells, the insular cortex and neuroprosthetics. For anyone looking to get the quick picture of these frontier research areas, this book serves as an excellent primer. It does an excellent job of making connections to socially relevant topics such as the secrets of athletic excellence, underlying causes of eating disorders and the modern obsession with plastic surgery. I have come to believe that neuroscience will eventually provide concrete explanations for the metaphors we use and the spooky phenomena we believe in but science cannot prove. Along those lines, this book does a great job of describing brain mechanisms that may underly paranormal phenomena like auras and out-of-body experiences.

One of my favorite parts is chapter six, a short chapter with a Phantoms in the Brain feel that presents some extremely jarring clinical examples of neurological problems potentially caused by body map disorders. It describes cases of individuals who want to have their limbs amputated because they feel like they don’t belong to them, individuals who no longer get feedback from their limbs as if they have disappeared, as well as cases of one woman who felt like she had three arms and three legs. That these cases exist are fascinating in their own regard; that there exists a systems-level conceptual framework with which we might understand the underlying causes for them is utterly incredible.

The implications of these ideas to AI are significant. What kinds of intelligent systems can we build by assuming that they have ego-centric representations of objects in their peripersonal space, or by assuming that their motor intentions are tickled by watching the movements of other creatures? The implications for computational neuroscience are also significant. What kind of system of neuronal processors is capable of producing cells that are sensitive to peripersonal space? What information must flow into those cells, and where is that information available from in the brain? Along what channels and using which “algorithms” does your brain map the visual information of a person moving their limbs to the motor areas that control your limbs? Perhaps I’ll be able to read about these things in the next Blakeslee neuroscience tour de force.

The Body Has a Mind of Its Own: How Body Maps in Your Brain Help You Do (Almost) Everything Better
by Sandra Blakeslee (Author), Matthew Blakeslee (Author)
Random House Publishing Group

(Full disclosure: Sandra Blakeslee and Random House kindly sent us a copy of the book to review before their release date…thanks guys!)

Guest speakers on May 9th will include MIT professors (Roz Picard, Hugh Herr, myself, etc.) and many acclaimed speakers such as Oliver Sacks and John Donoghue. Registration may be close to being full, but it will be webcast.

More information at:
http://h20.media.mit.edu

- Ed

Here is an old lecture about the feelSpace belt.

The Wired article also talks about other enhanced senses routed through the tactile sense (Wicab/Bach-y-Rita’s team’s tactile display, which we’ve discussed before (see also the tonguevision weblog), the same lab’s inner ear balance-detector replacement, and a device for pilots that tells you which way is down).

Also, I should mention that some people have had magnets implanted in their fingertips so as to sense magnetic fields. Don’t do this though; the magnet implants eventually become infected/rejected and have to be removed (although that article holds out hope that perhaps some day a better, safer design will be found).

Here are what I think are the most interesting parts of the (newer) Wired article, which have to do with the feelSpace belt.

… a wide beige belt lined with 13 vibrating pads — the same weight-and-gear modules that make a cell phone judder. On the outside of the belt were a power supply and a sensor that detected Earth’s magnetic field. Whichever buzzer was pointing north would go off. Constantly.

“It was slightly strange at first,” Wächter says, “though on the bike, it was great.” He started to become more aware of the peregrinations he had to make while trying to reach a destination. “I finally understood just how much roads actually wind,” he says. He learned to deal with the stares he got in the library, his belt humming like a distant chain saw. Deep into the experiment, Wächter says, “I suddenly realized that my perception had shifted. I had some kind of internal map of the city in my head. I could always find my way home. Eventually, I felt I couldn’t get lost, even in a completely new place.”

The effects of the “feelSpace belt” — as its inventor, Osnabrück cognitive scientist Peter König, dubbed the device — became even more profound over time. König says while he wore it he was “intuitively aware of the direction of my home or my office. I’d be waiting in line in the cafeteria and spontaneously think: I live over there.” On a visit to Hamburg, about 100 miles away, he noticed that he was conscious of the direction of his hometown. Wächter felt the vibration in his dreams, moving around his waist, just like when he was awake.

….

When the original feelSpace experiment ended, Wächter, the sysadmin who started dreaming in north, says he felt lost; like the people wearing the weird goggles in those Austrian experiments, his brain had remapped in expectation of the new input. “Sometimes I would even get a phantom buzzing.” He bought himself a GPS unit, which today he glances at obsessively. One woman was so dizzy and disoriented for her first two post-feelSpace days that her colleagues wanted to send her home from work. “My living space shrank quickly,” says König. “The world appeared smaller and more chaotic.”

Note however that the talk slides say that subjects did not claim that it gave them a new sense (I didn’t listen to the talk).

To summarize the most interesting info from the interview:

Berger’s team is trying to make a hippocampal prosthesis (a chip that could be implanted in the hippocampus and help people with damaged hippocampuses). (we’ve mentioned Berger’s team’s efforts before).

He admits that he doesn’t understand how the hippocampus functions in memory, but argues that you may be able to make a prosthesis without this understanding: “A repairman doesn’t need to understand music to fix your broken CD player.”

The first crucial test will be done later this year by Sam Deadwyler at Wake Forest. He will implant the chips in rats, deactivate their hippocampuses with drugs, and see if the prosthetic helps.

(UPDATE 03-05-2007 – Upon closer inspection, it is clear that while the surgery has enabled the woman to have sensation in the nerves of her missing hand when the surface of her chest is touched, the arm she is fitted with at the time of publication did not relay sensory signals from the arm back to her chest. As soon as she is fitted with an arm that has the appropriate sensors, however, she will not have to undergo further surgery to have this kind of direct feedback. Thanks to astute readers for pointing this out.)

The Guardian reports on an article published today in the Lancet about a successful surgical procedure giving an amputee a bionic arm that both responds to motor commands from her remaining motor nerves to control it and provides sensory feedback to sensory nerves when it is touched. If there was any doubt left, the worlds of neural prosthetics and brain-machine interfaces have officially collided.

The Lancet article is accompanied by two movies of the woman using the arm that you should really check out.

Given the recent progress in the decoding of motor signals from the brain and older progress on sensory feedback from neural prosthetics, this was to be expected. Nonetheless, watching this woman use her arm brings the message home in a visceral way. The spooky thesis of MIT CSAIL’s Rodney Brooks that “we will become a merger between flesh and machines” is one step closer today.

From the article:

Targeted reinnervation surgery was successful in this young woman. Four independent myoelectric sites were created that allowed improved control of a motorised artificial arm. Transfer sensation also developed; when the patient was touched on her reinnervated chest skin, she perceived the sensation to be in her missing hand.

An additional comment in the Lancet explains targeted reinnervation surgery:

Rather than record from these nerves directly, Todd Kuiken and colleagues report in today’s Lancet their development of targeted motor reinnervation (TMR), in which the disconnected ends of peripheral nerves are reimplanted into proximal musculature. Contraction of these proximal muscles shows the intended activation of the missing distal muscles. When combined with a myoelectric prosthesis, a command in the CNS to open the hand travels through its usual peripheral nerves, is amplified by the associated patch of reinnervated muscle, and is detected by myoelectric sensors, which trigger the prosthetic hand to open.

Todd A Kuiken, Laura A Miller, Robert D Lipschutz, Blair A Lock, Kathy Stubblefield, Paul D Marasco, Ping Zhou and Gregory A Dumanian, Targeted reinnervation for enhanced prosthetic arm function in a woman with a proximal amputation: a case study, The Lancet, Volume 369, Issue 9559, 3 February 2007-9 February 2007, Pages 371-380.

Though my queries may seem a bit ameteuristic, it is very important for me to get clarity on these doubts.
Hope my queries will be answered.
Thanking all of you in advance,
sudhi