There is precisely one thing about the human body that differentiates us from the other life on Earth. The difference is one of degree rather than perhaps of kind, but it is a difference so striking that one can't help but consider it the single defining characteristic of Homo sapiens. It's actually in our species name itself.

Sapiens. 'Sapient'. We think, therefore we are -- and we think with the human brain.

It's the organ that has made us the dominant large animal on the planet, the organ that allows us to live in a wider range of environments than any other species of mammal, bird or reptile, the organ that moved us from an opportunistic scavenger to the top of the food chain. And, in some cases, off of the normal food chain entirely. What we are is defined by 1450 or so cubic centimeters of neuron, synapse, ganglia and axon that we aren't very sure of when it comes to how or why it works. Our bodies could change, even die, but as long as our functioning brain (or a reasonable facsimile thereof) still exists, there's a general consensus that we exist.

And rather ironically, if there's one organ that gets repeatedly overlooked when it comes to the transformation genre, it's the one that's most important.

To be fair, it isn't necessarily ignored, but transformation of the mind is usually restricted to memory or personality changes or vague references to instincts, drives or urges that are associated with the new body form. To me that's as lame as restricting physical transformation to some known animal or anthropomorphized version thereof (or the other sex, I suppose). The brain is truly a fascinating bit of organic machinery, and the variations possible in transformation related to it are hardly ever explored.

In an earlier column I talked about the problem of authors not being able to get into the head of aliens. Well, there is actually a way of doing that, of imagining what someone with thought processes different from ours would be like. There are examples right here on earth right now: They're the malfunctioning brains.

The cause may be organic, congenital, or due to external causes, but it's thanks to people whose brains don't function right that we've gained some understanding into how properly-functioning brains do work. From a writer's standpoint, they offer insight into different ways of thinking or, specific to transformation, how actual physical changes in the brain could result in some truly different ways of relating to the world.

Dr. Vilayanur Ramachandran has become something of a celebrity because of his work with people who have suffered some kind of problem with the brain, and if you've seen him on various science specials on TV you'll know some of the things I'm going to talk about. You might try googling his name to get some interesting links.

First, the general concept: Many researchers consider the human mind to be composed of different parts of the brain carrying out specific functions or roles, the consensus output of those functions being what we call 'human consciousness'. Many of those parts may, on first examination, seem to be pretty trivial -- or at least not critically important to our way of looking at the world. For instance, Ramachandran has described an area of the brain responsible for associating emotional response with specific forms of sensory input (located in the thalamus). The smell of a specific flower may trigger a feeling of happiness because that's the flower your first date sent you, that sort of thing. Now if that area of the brain suffers some sort of damage, or the sensory inputs into it are screwed up, you might think the worst that can happen is that you don't get the feeling of happiness. The world might seem a bit poorer, but hardly anything earth-shaking, right?

Wrong!

The concept of the brain composed of two hemispheres with differing functions is an old saw that you've no doubt heard. "Are you right-brained or left-brained? Take the test!" Well, it's not entirely incorrect. Current research suggests that one hemisphere takes sensory input from the outside world, mixes it with memory and such, and presents a 'story' of what's happening. The other hemisphere acts as a combination editor/fact checker/censor. It looks at the story and evaluates it based on assorted criteria, basically deciding if the story makes any sense. Normally the two hemispheres cooperate well, and you don't notice anything happening. But if something goes wrong, well, it's a different story.

Let's go back to the screwed-up emotional response. The way the emotional response normally works is that input from, say, the eyes, gets routed to the vision centers to be evaluated. That evaluation now takes two different routes. One heads directly to the reasoning sections, the other is routed through the emotional response center (I'll abbreviate it ERC) and then to the thinking parts. Example: You see your parents. The vision center identifies them and sends that recognition to the ERC and your reasoning sections, and the ERC flips that signal to the reasoning center with the appropriate emotional responses (love, affection, fear, whatever you associate with your parents).

Now imagine that the signal path from the vision center to the ERC has been damaged. No signal gets through. You see your parents... but there's no emotion associated with it. The problem is that your brain knows it should be receiving an emotional response, because of the memory of past responses.

The 'story' hemisphere is merrily chugging along: "And here's two people, oh look it's my parents, I wonder if they..." when suddenly the other hemisphere breaks in.

"Hold it! Something is wrong. They might look like my parents but I'm not feeling anything. Since I'm not feeling anything but I should, those can't be my parents. Left Hemisphere, fix that story."

Left Hemisphere pauses for a bit. "Well, okay, if they aren't my parents then they must be someone else who looks like my parents. Impostors! That's it, they're strangers who have taken my parents' place!"

Right Hemisphere considers that. "Fits the available facts. Carry on."

This might sound unlikely, but it in fact happens. One man suffered a brain injury in a car accident, and following the accident was convinced his parents were impostors. The interesting part is that it was only signals from his eyes where the data stream was corrupted. When he couldn't see the 'impostors', but spoke to them on the phone, he had no problem recognizing them as his parents because the signal from his hearing hadn't been damaged. The sound of their voices triggered the appropriate emotional response.

Damage to the right hemisphere, say from a stroke, can cause other interesting effects. The Left requires the Right's editing: it can't change its own story otherwise, no matter how absurd the story gets. It ignores anything that contradicts its view of the world. This can lead to an interesting situation when, say, an arm is paralyzed by the same stroke that damages the Right's editing capability. The Left side can't change its story: It sees the arm is there. If it's there, it should be able to move it. Therefore it's not paralyzed. So the patient keeps insisting they're not paralyzed, because the Right side isn't there to update the overall way the brain sees the body. The patient is literally unable to change that point of view.

The Left and Right also appear to process language differently. The Left handles the meaning of language, while the Right processes metaphor, ambiguity and so on. To explain it simply, the Left is literal. It takes the phrase 'a piece of cake' and understands it, but the Right interprets it for context; do you mean an actual slice of cake, or do you mean 'easy'?

Damage to the Right can cause a person to lose the ability to understand nonliteral messages. They won't know that 'a piece of cake' means 'easy'. They won't get jokes or puns or songs or poetry, or anything else that isn't a simple statement of fact. Play them Warrant's Cherry Pie, and when they hear the lyrics "Swingin' in there/Cause she wanted me to feed her/So I mixed up the batter/And she licked the beater", they'll wonder what's so special about baking while the rest of us are giggling (or outraged, I suppose) about the obvious allusion to oral sex.

Another interesting brain 'malfunction', which doesn't actually involve any damage to the brain, per se, is phantom limb syndrome. A few decades back Walter Penfield demonstrated, through direct stimulation of the brain's surface, that areas of the brain mapped to areas of the body. Touch your hand and an area of the brain lit up. Touch that area of the brain with a current and you'd feel tingling that apparently was coming from your hand. If, however, a particular section of the body is missing or paralyzed, through nerve damage or whatnot, the corresponding area of the brain doesn't receive input. Over time, it appears that input from neighboring areas of the brain can 'leak' into the inactive portion, which causes the person to feel pain in a section of the body where they shouldn't, either because the nerves have been so damaged they can't feel pain, or because that body part is completely missing.

There are some interesting ramifications depending on what parts of the body are involved. In the standard diagram of the Penfield map, the section mapping to the genitals is right next to the toes and feet. Some of you sick puppies with your minds in the gutter already know where this is going, right? Yes, that is correct; there is a neurological basis for foot fetishism. Stimulation of the feet and toes could, in some people, 'leak' over into the area mapping to the genitals.

This can lead to an interesting situation for people missing their feet. If stimulating the feet can fire off the section of the brain that normally reacts to sexual sensation, then the reverse is true: When someone with an amputated foot has sex, they could possibly feel it in their (missing) foot. In one case, a man had better sex after losing his foot. It's theorized that he had a lot of leakage from the genital map to the foot map, and his brain came to the conclusion that he was feeling pleasure from both, even though in reality it was just his brain double-dipping the same stimulus.

Getting back to the Penfield Map, not all the areas of the body are treated equally. The brain area devoted to any part of the body isn't necessarily related to that part's actual size. A model of what the body would look like if the parts were sized according to the amount of the brain devoted to handling sensory data from that part is known as a 'Penfield Homunculus', and one sculpture showing what it would look like can be seen here. As you can see, much of the brain is devoted to the hands and the face (especially mouth and tongue). Which, when you consider it, makes sense. Our hands are extremely versatile manipulative appendages, and the fine manipulation we're capable of means they have to be very sensitive to touch and their position in space, and the processing power of handling that is allocated accordingly. Speaking and language requires similarly fine manipulation of the lips, mouth and tongue.

So imagine if that were changed, either by altering the brain or placing the brain in a new body. A quadruped human would find their 'front' feet overly sensitive, because more of the brain was taking input from that area than their rear feet. Alternatively, reduce the dedicated brain area and suddenly fine finger manipulation, possibly even speaking, become difficult or impossible.

So, back to what I said at the start: What does this very brief introduction to current brain theory have to do with the writer of transformation?

Well, what happens if the agency responsible for the transformation of the body plays with the brain? Suppose it remaps the Penfield Map so that all of a sudden stimuli that should be affecting the genital portion of the map is switched with that of, say, the ears (to blatantly steal a suggestion from a Star Trek species)? All of a sudden manipulating the genital region is as stimulating as scratching your ear, while a lover whispering in your ear could cause you to orgasm.

Suppose that agency permanently disconnects the emotion area of the thalamus? Now you don't have any of the emotional responses you should. You become paranoid as you wonder who removed you to a world that's exactly like your own, full of impostors. Hell, you look in the mirror and don't recognize who you are.

Disconnect the Right Hemisphere's language center; you become utterly literal, and someone speaking in metaphor might as well be speaking a different language. You can understand the words, and know the meaning of the words, but you don't understand what they're really saying. "Hey old boy, top of the morning" would be utterly incomprehensible.

Or disconnect the section of the brain that recognizes animals. If someone asked you to describe a lion you could, but when shown a lion you'd have go through a process of elimination in order to figure out what it was. Or take away the ability to recognize faces. Or the meaning of words. Or, or or...

Perhaps consider that the change wasn't planned at all but merely a side effect of the physical alteration. You still could have weird effects. Apples tasting purple. A singer's voice that smells bad. Feeling fingers even though they've been lost as the arms were changed into wings. Maybe the senses are remapped so that the primary sense we use, vision, is swapped for the primary sense in the new form, say smell. Now certain smells have a color, or a light pattern associated with them.

So on and so forth and et cetera.

What I'm getting at is that there is a hell of a lot more possibilities than simple download of Personality 1.0 into Body 2.0 and everyone carries on. By thinking of some of these possibilities you, the writer, open an entirely new dimension in describing the world of someone who has changed in body and, more importantly, in mind.