There is a specific part of the brain that stores memories. [ He doesn't even bother -- he just rolls right into it, hands in his lap, legs crossed, a smile on his face. ]
The limbic system is... about -- [ He taps the not-quite-top of his head with a grin. ] here. Well, around here. It's a set of brain structures including the hippocampus, amygdala, anterior thalamic nuclei, septum, limbic cortex and fornix, which support a variety of functions including emotion, behavior, long term memory, and olfaction. By now, I'm sure most of us are familiar with amnesia. It's a condition in which one's memory is lost. [ He makes a gesture with his hand, flicking it, then joining his hands together again and placing his elbows on the table. ]
The causes of amnesia can be split up into different categories. Supposedly, they can be any condition that interferes with the functions of this particular system. [ He pauses, smile never faltering. ] For example, mental disorders, post-traumatic stress, and defense mechanisms. [ Another pause. Just to let that sink in. Then, he leans back, unlinking his hands. He holds up a hand -- two fingers out. ]
There are, in fact, two different kinds of amnesia. [ One finger goes down. ] Antereograde amnesia, and... [ The other raises once again. ] retrograde amnesia. [ He gestures with that same hand. The guy is practically talking with his hands. ] Retrograde amnesia is the loss of pre-existing memories to conscious recollection, beyond an ordinary degree of forgetfulness. Think of it like a full tea pot. The liquid can be poured into a cup, essentially removing the tea. However, the tea can be replaced. Though, it isn't generally seen as good manners to pour tea back into a tea pot. [ He chuckles. ]
Memories can be categorized as well... procedural memory can be automated skills, where as more personal memories like your name, or a specific episode that occurred to you, those are classified as declarative memory. Only one is generally affected. Let's say a man forgets things like his name, address, family, who he is, where he's been in his life, and everything that's ever happened in his life that has made him into the person he presently is. However, he learned piano at some point in his life. The time at which he learned this skill isn't really important. He learned it, that's what matters. He doesn't forget how to play piano. In fact, he plays just as well as he had without his amnesia. Personal details are declarative memories. Something like being able to play an instrument is a learned skill, so it falls under procedural memories. The tea that was poured into the cup was his declarative memories, so to speak.
As I said, there are a lot of causes for amnesia. Stress, trauma, mental disorders... [ his words linger for a moment. ] Well, the possibilities are endless. I can't help but wonder... if I'm forgetting all these things in response to something else.
... Sorry, I was just kidding.