Books — A Brief Tour of Human Consciousness

A Brief Tour of Human Consciousness

 

By Lisa Parsons

 

Brief Tour boggles, in a good way

Brain book will make your head spin

 

A Brief Tour of Human Consciousness, by V. S. Ramachandran, Pi Press, 2004, 192 pages.

You think you perceive things as they are, but you don’t. Take out some neurons here, cross-wire some neurons there, and your reality becomes entirely different — and you will swear that you are right and everyone else is wrong. You will know that you are right and we are wrong.

You will know, for instance — if you have damaged a particular part of your brain — that the woman standing over there looks exactly like your mother but must be an imposter. Except, she’s your mother. We know she is. And aside from this glitch, you’ll be perfectly fine. Vision, check; mental arithmetic, check; crosswords, driving, grocery shopping, check, check, check. You hear your mother’s voice, you’ll say, “that’s my mother.” You see her face, you’ll say, “looks like her, isn’t her.”

What does that mean?

How could your vision and thought processes work fine, your ability to identify objects work fine, and the only thing that’s wrong is you suddenly insist your mom’s a fake — but only visually?

Honestly, if this doesn’t make you want to be a neuroscientist when you grow up, there’s no hope for you.

V.S. Ramachandran, director of neuroscience research at the University of California in San Diego, has a theory about this phenomenon, which is called Capgras syndrome and extends to anyone emotionally close to the afflicted person. Ramachandran’s research indicates that Capgras syndrome results from damage to brain cells linking the fusiform gyrus, which handles visual recognition, to the amygdala, which gives us emotion. Ramachandran postulates that when we recognize the face (fusiform gyrus works fine) but experience no emotional response to that recognition (fusiform gyrus signals don’t reach amygdala), we “know” it’s not our mother (or brother or whatever).

Ramachandran describes other intriguing syndromes. Phantom limb is one you’ve probably heard of, but how about the syndrome known as neglect, in which a person ignores one hemisphere of his personal space? This happens when there’s damage to certain areas on the brain’s right side, often causing paralysis to the left side of the body, but it’s not the paralysis that leads to indifference; not only will the patient not use the left side of his body (he can’t) but he’ll totally neglect everything in the left half of space for him. He’ll eat food only from the right side of a plate. Asked to draw a flower, he’ll draw the right half of a flower. Surely if his right hand is capable of drawing half a flower, it could draw a whole flower. So why doesn’t he?

And then there’s blindsight (you can’t see, but you can accurately point to an object when you give it a try to humor the doctor), mirror agnosia (you can identify objects, but not when you see them in mirrors), synesthesia (a crossing of perceptual modes, so you perceive numbers as having color or flavors as having shape, etc.), depersonalization (you perceive that you’re not quite real) and derealization (you perceive that your surroundings are not quite real)—those last three not necessarily implying disease or damage but merely a heightened expression of normal phenomena.

In this slim, accessible volume, Ramachandran surveys all of these and more to highlight consciousness, free will and how our brains parse reality. He discusses art, which he promises to examine in a later book. (His popular earlier book, Phantoms in the Brain, was made into a television show.) While you read it, your brain will be busier than you can fathom.

- Lisa Parsons

 
2004 HippoPress LLC | Manchester, NH