Summarized from: The 5 Most Terrifying Ways Your Brain Can Turn on You | Cracked.com
This article was so crazy, I had to post it. Below is a summary (and more info provided by wikipedia):
5. Attack of the Jibber-Jabbers
Patients with receptive aphasia
aka Wernicke's aphasia (this is usually found people recovering from a stroke) believe they are speaking normally, but what will others hear is total gibberish. They can speak one sentence without issue, and the next will be complete nonsense. They are also unable to understand spoken or written language. Strangely enough, the part of the brain that remembers song lyrics is unaffected, so you could still sing a song with no trouble. Weird, huh*?
HOW IT WORKS: When we speak, we formulate our sentences in the Wernicke's area of our brain and those sentences are transmitted to Broca's area, where we can then speak from. The "speaking gibberish" aspect of aphasia comes from neurological damage to the Wernicke's area, but other difficulties stem from damage to the medial temporal lobe. Damage here destroys local language regions and also cuts off many other part of our brain from the core language region.
4. Motion Blindness Turns Everything into a Slideshow
Imagine being unable to see motion; people walking are frozen in time, holding a glass of water upside with nothing spilling out... blink, and everything has moved, but is still frozen. This disorder is called akinetopsia
(aka motion blindness) and it is extremely rare. You can still hear sound though - which I imagine would be super weird to hear people yelling or running but visually, they appear to be standing still. Pouring a glass of water would be difficult to do without it overflowing, and writing anything down would be hard too. Patients have to try to get by on the sound cues, much like blind people. I guess you could just constantly blink, which would make the whole world seem like a frame-by-frame motion picture. Kinda cool, but depressing at the same time.
HOW IT WORKS: One way akinetopsia is caused is by lesions in posterior side of the brain's visual cortex, which allows our brain to process motion. In the case of L.M (the most documented case), the lesion was small enough to not effect other visual functions of the brain. This is a rare way to acquire akinetopsia because the lesions usually interfere with other parts as well. Alzheimer's patients may also suffer from varying degree's of akinetopsia. It has also been reported as a result of traumatic brain injuries.
3. Refusing to See Anything on Your Left
is a neuropsychologial conditions which makes you literally UNABLE to see anything to your left/right. When things happen on your left side (seeing something, stubbing a toe, etc.) the right side of your brain processes that information. If your right parietal lobe is damaged in any way (stroke, lesions, tumors, injuries), you won't be able to process what is happening on your left. It has nothing to do with the fact that your left eye doesn't work (it's more equal to being unable to use the left side of each eye), but that your brain can't make the connection. This picture shows what a hemineglect person sees when asked to copy a picture:
Not only to they not see on one side, they have been reported to ignore voices from one side, eat only the food on one half of their plate, and neglect one side of their bodies (for example, only putting deodorant under one armpit or brushing one side of their hair). Also, when asked to draw a clock, they will draw the whole circle, but put all of the numbers on one side of the clock and leave the other half blank. Strange, or what?
HOW IT WORKS: Like I previously started, it can occur from brain injury, stroke, lesions, or tumors in one hemisphere in an area that allows us to process and perceive stimuli from one side of our bodies. Very rarely does right-sided spatial neglect happen because both the left and right sides of the brain help to process that information, so the right side is able to compensate for the loss of the left - but not vice versa. It CAN be treated by slowly trying the draw attention toward the left of the patient just a few degrees past the midline and progressing from there. There are other forms of treatment using lenses and prisms.
2. Only Seeing One Thing at a Time
Patients with dorsal simultanagnosia
have a similar problem to those with hemineglect, but instead of being able to only see one SIDE, they can only see one THING. Think of when you are watching TV and there's a fly on it. Soon enough, you don't even see the fly until you see it move again. It's kind of like that, but they LITERALLY only see the TV. The fly doesn't exist, the table the TV is on doesn't exist, the thief sneaking around your house doesn't exist... you get the point. Their brains can only process one thing at a time. This means if they were put in a new room they've never been in before, they would have to look at each individual object until they could piece together where they are. For example, a classroom: People without dorsal simultanagnosia would walk in instantly see the classroom, but someone with the problem would have to look around and think "clock - desk - books - children - chalkboard - oh, it's a school classroom." Below is the image used to help diagnose this condition:
Patients may say they see a boy, a stool, or curtains, but they are unable to interpret the entire scene.
HOW IT WORKS: Like most of the other conditions on this list, it's caused by trauma, lesions, or a stroke, but this time it occurs where the parietal lobe and occipital lobe meet. This causes the brain to be unable to see/process an entire scene at a time.
1. Time Becomes Meaningless
This one is SUPER CRAZY. Do you know what day it is? Did you know Christmas is in the wintertime? Did you eat lunch - if so, what did you eat? DO YOU KNOW HOW OLD YOU ARE?
If you can answer those questions, then you don't have time agnosia
. Congratulations! People with this condition are unable to sequence events. For example, you would know you ate a delicious meatball sub from Subway for lunch, but you wouldn't know if that lunch was today, or last year. All off your memories have been stored, but in no particular order. They can't even grasp the concept of seasons. One patient even lost the concept of what a day WAS and had no idea that everyday would end with her going to sleep and then waking up next morning. INSANE.
HOW IT WORKS: There are many types of agnosia. For example, phonagnosia is the inability to recognize familiar voices, visual agnosia is the inability to recognize objects, and remember #4 - Akinetopsia (the inability to see motion)? That's a type of agnosia too. Time agnosia is mainly developed from brain trauma to the part of our brain that processes time and events. Fortunately, it gradually heals over time (how quickly depends on how severe the injury was), so at least there's that. ^_^