I find it amazing how humanity ventures mind-bogglingly far into outer space, recreates history as far back as like 14.7 billion years ago and whatnot but still we know so very little about some aspects of ourselves.
A typical example is our loose grasp on the functioning of the human brain and scientist' pathetic attempts at explaining the weird (and if you are cynical enough - hilarious) things that can go wrong with it.
Studying the Brain
A good start of getting introduced to some lesser known brain malfunctions is taking a look at the way our brains work was studied. It was known to man that the brain is responsible for thought as far back as Hippocrates. How did he get this insight, you may wonder. Well, it's very simple - he observed the problems that people with brain damage are having.
What some might find even more puzzling is that an ancient form of cranial surgery has been performed since the Neolithic (end of the stone age, 9,000 BC) - people then believed that drilling holes in the skull relieves the pressure inside the head and cures certain diseases, and somehow managed to do it with their primitive tools.
It turns out that this field advanced significantly with the industrialization of the world - and that's quite a straightforward relationship. The machines - and especially vehicles - are a steady source of humans with damaged brains and occasionally - with intact bodies. Studying these cases gives scientists an opportunity to study what exactly goes wrong with people with specific parts of their brains damaged and to thus infer what these parts might be responsible for.
At first they found it puzzling how people with what appears to be severe brain damage were able to get on with their lives surprisingly well. Take a look at this, for example:
So, both the guy and the rod are the same on both pictures, and surprisingly enough, the one on the left is done later. This guy (Phineas Gage) had his head literally impaled on the rod and not only survived but became sort of a celebrity.
People with this kind of injuries, however, experience certain changes that reveal a lot about the function of the affected areas. Of course it didn't take scientists long to figure out that they might as well inflict this to animals and they diligently destroyed various parts of a wide range of animal brains and observed how animals reacted. Animal rights activists will probably find this extremely objectionable but one might argue what's a reasonable price tag for obtaining the knowledge about how our brain works. I personally will probably place it higher than experiments on animals and lower than actually destroying parts of people's brains.
But anyway, let's not cut any animal's brains for now (unless it's for culinary purposes) and instead take a look at some intriguing conditions that occur naturally. Popular culture has formed vivid (although not scientifically correct) images of some "mainstream" diseases, like schizophrenia, insomnia, paranoia, etc. but there are some rare cases that are even more curious:
This is defined in wikipedia as "a deficit in attention to and awareness of one side of space", i.e. people either fail to percieve or ignore, or maybe just don't care about their left or right side.
It has different forms - ranging from rejecting the existence of one's own side of the body (resulting in patients complaining about a dead man's leg being stuck under their blanket) to inability to percieve anything on their, say, left hand side.
When some people with this condition are presented with a picture they can only perceive its right hand side. And it's getting even weirder - when they are presented with a well-known image, e.g. the face of a relative, that is turned upside down - they still only see the right side, although it's technically on their left, where they are expected to ignore everything. So this gives us an important clue - when we see an image that we recognize as upside down our brain rotates it first before starting to process the information. And no, this is not an excuse to upload sideways and upside down images on facebook - you'll still look like a moron if you do.
Alien Hand Syndrome
This is a neurological disorder, the sufferrers of which poses no control over one of their hands (or some other body part occasionally - not counting the penis, that's another phenomenon that's much more common).
In much the same way that some of the science fiction from the past predicted the world that we now live in, Kubrick predicted this condition with Dr. Strangelove. In this cult film (one of my favourites) the character with the same name is a weapons science consultant for the US military with a rather naziish look and a hand that occasionally does the nazi salute seemingly out of his control.
Incredible as it may sound, this later turned out to be a real desease and there are people who's one hand appears to be totally "under alien control". To make things worse, there are a lot of documented cases of the alien hand being really counter-productive like stubbing out one's own cigarettes, doing the classical "stop hitting yourself" bully manoeuvre, spontaneously undressing or slapping a colleague's butt. It kind of has the "coolness" factor of Tourette's but instead of swearing you are allowed to actually touch!
Tourette syndrome is also a curious case but it was made well popular by South Park so I'm assuming you've heard about it and won't cover it here - after all I don't take seriously people who haven't seen all South Park episodes.
Now back on the AHS - it's a reasonable thing to ask who then controls the alian hand (if you don't buy the story with actual aliens with remote controls slapping people's butts with your hand)? It turns out to be your other hemisphere! It's like each of your hemispheres has a separate consciousness and usually the left one is dominant and has the final say. Sometimes, however, the right hemisphere takes a hold on a limb and decides to disobey the ruling elite - and you definitely don't want any democracies and shit like that in the way you rule your body parts.