Dispatches from a rapidly changing, rapidly improving world

Special Dispatch April 15, 2009

It's tax day here in the good old US of A: as good a time as any to remember that, whether your take is that it's happening because of massive government spending or in spite of massive government spending, life in this country -- and pretty much everywhere else -- is improving.

Item:
Doctors confirm woman's imaginary third arm

A 64-year-old woman has reported to doctors at Geneva University Hospital the presence of a pale, milky-white and translucent third arm.

After examining the case, the woman's neurologist, Asaid Khateb of the hospital's experimental neurophysiology laboratory, called the rare phenomenon credible.

The arm appeared to the woman a few days after suffering a stroke, doctors said.

But this case of what is known as a supernumerary phantom limb (SPL) is a genuine head-scratcher.

The upshot is that the woman can use the apparitional extremity to relieve very real itches on the cheek. It cannot penetrate solid objects.

Khateb and his colleagues examined the patient's brain using functional magnetic resonance imaging (fMRI), a tool that allows doctors to see whether the brain is truly stimulated, and to pinpoint where. In this case, the investigations revealed that the woman actually experienced what she described.

Researchers instructed the woman to move her right hand. As expected, the motor cortex and visual processing areas in the left side of her brain became mobilised.

The same effects were observed to a lesser extent when the woman simply imagined moving her right hand. Imaginary movements of the woman's paralysed left hand prompted the same activity in the brain, but on the right side.

But when doctors asked her to move her phantom arm, her brain reacted as though the arm really existed and could be moved. In addition, the patient's visual cortex was also activated, indicating the she actually saw the imaginary limb.

And when she was instructed to scratch her cheek, regions of the brain relating to touch were activated

The Good News

Yes, this item is Better All the Time, not Astounding Science Facts (or Tales of the Paranormal.)

Here's why: it is extremely significant that the doctors treating this woman were able to use an MRI to take a peek at what's happening inside her brain and confirm that it is sending signals that mean move the arm and receiving signals that mean the hand is feeling something. Mapping brain activity to physiological phenomena is one of the biggest breakthroughs of the past few decades, and its promise is already being realized in a number of different prevention and treatment options.

Consider this: earlier this week, my newborn daughter was subjected to her first-ever hearing test. The pediatrician hooked her up to an electroencephalograph, put headphones on her, and started piping in sounds. In a matter of minutes, the brainwave scan confirmed that she is hearing everything she should be hearing in each ear. Great news for new parents when there is no problem, and extremely useful in the unfortunate cases where there is a problem. Rather than waiting months or years for a child's behavior to reveal that something is amiss, these parents know what they are up against from the very beginning.

Mapping the motions and sensations of a real limb to brain activity makes it possible to treat paralysis by overriding existing damaged nerve connections in order to return mobility to a paralyzed limb. Such mapping is also crucial to developing a direct interface between the brain and electronically controlled prosthetic limbs when there is no possibility of reviving the lost function, as in the case of amputation. These kinds of treatments are already under development.

But that's just the beginning. Understanding how a phantom limb is represented within the brain gives us a glimpse of how one day -- probably not that far in the future -- we will be able to have very real experiences in virtual worlds. The woman described is experiencing something that seems perfectly real to her, as real as the actual experience of her actual arms. Essentially, her brain has written and is executing a "program" for a virtual arm. Seeing as this came about as the result of a stroke, and the woman probably wasn't looking for an extra limb, we tend to view this new bit of mental software as a bug. But that bit of spontaneous buggy "software code" embeds some powerful capabilities. That her doctors are able to watch it in action is a very good sign. In time, it's reasonable to expect that someone will figure out how to reverse engineer this program, and begin to improve on it.

Live to see it!