Targeted reinnervation

A woman’s nerves have been rewired to help her control a prosthetic limb, an experimental procedure for amputees called targeted reinnervation. It’s a fascinating concept, and it works: a noncritical muscle’s nerves are deactivated, and the severed efferent (motor) nerve fibers from the missing limb are inserted into the muscle. The brain can then control a prosthesis by sending motor signals to the muscle. Additionally, the afferent (sensory) nerve fibers from the severed limb are moved to the skin above the same muscle. Stimulation of those nerves are now mapped as sensation originating from the prosthesis. Claudia Mitchell can control her prosthetic arm by sending motor signals to her chest muscle, and experiences cutaneous sensations in her prosthetic arm when the skin on her chest is touched or its temperature is changed.

Of course, rather than simply explaining the news in as clear a way as possible, ABC proceeds to extremes: “Mitchell has become the first real ‘Bionic Woman’: part human, part computer.” She’s first and she’s real, and you can tell because ABC even awarded her the official capitalized title of “Bionic Woman.” Presumptuous, and also inaccurate. In fact, this technology is exciting because it doesn’t have much to do with computers at all. Rather than relying on predictive software to control the motors in the prosthesis (which was the technique used in this BBC producer’s prosthetic foot), Ms. Mitchell controls her hardware directly, with her brain.

In any case, the success of this procedure has led to some interesting discoveries, such as the fact that Ms. Mitchell retains a 1-to-1 mapping of her reinnervated afferent fibers to locations on her prosthesis.

Paul Marasco, a touch specialist and research scientist with the Rehabilitation Institute of Chicago, was brought in to study the hand sensations that Mitchell feels in her chest. He put together a detailed map, connecting what Mitchell’s missing hand feels with the corresponding locations on her chest.

Depending on where you touch her chest, “she has the distinct sense of her joints being bent back in particular ways, and she has feelings of her skin being stretched,” Marasco said.

If a human’s nervous system can be extended to include a prosthesis, it isn’t a stretch to imagine that it can be interfaced with external signal networks, such as other humans’ nervous systems, or the internet. How will this affect embodied cognition? Societal structure? Consciousness?

Here’s a video of Claudia in action. Seems like she’s got style too—the upper part of her artificial arm is covered in a camoflauge pattern. Seen!

Philosopher deathmatch, and how words are like tools

9780060936648I just finished reading Wittgenstein’s Poker. From the jacket:

In October 1946, philosopher Karl Popper arrived at Cambridge to lecture at a seminar hosted by his legendary colleague Ludwig Wittgenstein. It did not go well: the men began arguing, and eventually, Wittgenstein began waving a fire poker toward Popper. It lasted scarcely 10 minutes, yet the debate has turned into perhaps modern philosophy’s most contentious encounter, largely because none of the eyewitnesses could agree on what happened. Did Wittgenstein physically threaten Popper with the poker? Did Popper lie about it afterward?

The authors provide a comprehensive biographical and historical context for the incident, and use it as a springboard into the two men’s respective philosophies. It’s an enjoyable look at two self-important, short-tempered intellectuals and their rivalry.

As I mentioned in this post, I find Wittgenstein’s philosophy of language often invokes touch themes. In the following excerpt from Poker (originating from one of his lectures), Wittgenstein makes a point about a colleague’s statement, “Good is what is right to admire,” utilizing a haptic metaphor:

The definition throws no light. There are three concepts, all of them vague. Imagine three solid pieces of stone. You pick them up, fit them together and you now get a ball. What you’ve now got tells you something about the three shapes. Now consider you have three balls of soft mud or putty. Now you put the three together and mold out of them a ball. Ewing makes a soft ball out of three pieces of mud. (68)

Another example stems from Wittgenstein’s midlife change in philosophical outlook. In his first publication, the Tractatus Logicio-Philosophicus, he was preoccupied with the “picture theory of language”—the idea that sentences describe “states of affairs” that can be likened to the contents of a picture. Later, he developed a theory of language based on words as tools for conveying meaning. In my reading, he shifted from a vision-based to a haptic-based (in fact, a distinctly physical-interaction-based) understanding of how language works.

The metaphor of language as a picture is replaced by the metaphor of language as a tool. If we want to know the meaning of a term, we should not ask what it stands for: we should instead examine how it is actually used. If we do so, we will soon recognize that there is no underlying single structure. Some words, which at first glance look as if they perform similar functions, actually operate to distinct sets of rules. (229)

Here’s the relevant passage directly from Philisophical Investigations:

It is like looking into the cabin of a locomotive. We see handles all looking more or less alike. (Naturally, since they are all supposed to be handled.) But one is the handle of a crank which can be moved continuously (it regulates the opening of a valve); another is the handle of a switch, which has only two effective positions, it is either off or on; a third is the handle of a brake-lever, the harder one pulls on it, the harder it brakes; a fourth, the handle of the pump: it has an effect only so long as it is moved to and fro. (PI, I, par. 12)

Words as the physical interface to meaning. Love it!

Automatically sync your music to your body

That’s what Yamaha’s BODiBEAT promises to do. More specifically, it syncs the tempo of your music to your gait. It’s been released as a workout tool, but it’s also an interesting musical interface as such, and if it works it will no doubt find its way into electronic music performance very soon.

(via Engadget)