author : Sandra Blakeslee

Some people who have lost a limb still feel pain in it -- they have a phantom limb. What causes this? There have been many theories, but Ramachandran seems to have tracked down the cause -- the brain holds an active map of the body, and this map can go awry when its input is disturbed. The map is no longer getting input from the missing limb, so it confabulates input. The pain is literally "all in the mind", but no less real for that. This suggested some very simple experiments, which had the unexpected effect of curing the pain, even making the whole phantom limb vanish, in some cases.

Ramachandran talks about not just phantom limbs, but other strange effects the mind can play when its input is disturbed or destroyed in some misfortune. We have phantom visions, blindsight, neglect and paralysis denial, temporal lobe disorders, and a host of other weird effects. What makes this book more fascinating than a mere cataloging of strange brain problems, however, is Ramachandran's discussion of the causes of these problems, and the several brilliantly simple experiments and tests he had done to distinguish between various theories.

Like Oliver Sacks, Ramachandran obviously cares about his patients, and the simple tests he performs have gained deeper understanding to help them, and others like them. Beautifully written (although the footnotes sometimes seem to be commenting on a slightly different text), and deeply thought provoking.

This is another good "how the brain actually works is really weird" books. This one is about the multiple "maps of the body" in the brain: how they help us do, think and feel; and what happens when they disagree with each other, or go wrong in other ways. The "going wrong" part can range from simple bodily illusions that anyone can experience, to musician's cramp; it can mean that someone now feels that they have three arms and legs; it can be full-blown anorexia, or a body dysmorphia where someone want a limb amputated because it isn't a part of their body.

One particular area of interest (to me, anyway) is the mind's sense of the body's state. Our usual "five senses" are outward-looking, sensing the world, and these are the ones we typically try to replicate in robots (and then, mainly vision, sometimes sound -- only specialist "sniffer" robots have a sense of smell, for example). However, we also have sophisticated sensing of our internal state: orientation of joints, stresses and strains of muscles and tendons, heart rate, and so on. We are just not quite as conscious of it, but it is essential for movement, and affects the way we think and feel (for example, holding a smile makes us feel happy!) Such sophisticated internal senses may therefore be crucial for robots, and researchers are beginning to add in analogues of these (from simple self-monitoring sensors to artificial endocrine systems). These may need to be much more deeply embedded -- embodied -- than those of current systems, however.

There is a lot of fascinating stuff here. It feels a bit choppy, a gallery of weird happenings, without sufficient depth about what's actually happening, and no bibliography to follow up interesting snippets. That somewhat academic criticism aside, this is a good introduction to how what we feel and experience is so heavily modulated by different areas of the brain that it might sometimes bear no resemblance to "reality" at all.