Day 32

What the hell is that --> ?

Well... that is what our brains do the entire time we have our eyes open. That is vision, to be succinct, it is the process our brains go through to make sense of these light waves and quantities of mass we interact with on a daily basis. Vision isn't one fluid apparatus, but rather multiple systems interacting together to produce the result that we all know as sight. And what is in this picture isn't even all of it! If you damage V4, you could lose your ability to perceive color. If you damage V5/MT, you could lose your ability to perceive motion. If you damage V2, you could lose your ability to perceive depth. If you damage V1, you could lose your ability to perceive all together. The eye is merely the first step, it's a window that the brain looks through to perceive what's out in front of us. It is an amazing system really. But the reason I put this up on here, is because I just gave a seminar on the posterior parietal cortex, that you see in the top left and top right of the pictures. This structure is responsible for not only sustaining our visual attention, but plays a role in our visual short term memory and change detection. Without it, you could theorize the world would disappear as it appears, like painting a picture but each stroke is erased just before the next one gets laid down. It is the parietal lobe that is damaged in visual neglect patients, but curiously, it is only when the right parietal cortex is damaged that they experience the neglect. Meaning, they literally "ignore" the left half of their world. Their vision is fine, it is their ability to pay attention and recognize things in their left world that is hampered. If you ask them to draw a flower, a house, anything, they will simply draw the right half of it. As if it was some sort of joke, when you point out the parts they missed, they will be just as surprised as you are - "how did I miss that?" seems to be a common phrase. The reason the right parietal cortex causes neglect but not the left is an interesting theory, it is said that the left parietal cortex has representations of the right visual world. Whereas the right parietal cortex has a bilateral representation of visual space, it "sees" the left and right sides of the visual world. If you are still with me, damaging the left parietal cortex would result in the left parietal cortex's failure to "see" the right side, but lucky for you, the right parietal cortex can now take over the role of the left. However, if the right parietal cortex was damaged, there is no longer a structure which has a representation of the left side of space... hence, neglect. If you can't tell already, I love the visual system, everything about it intrigues me to the fullest. That being said, the presentation Kim, Kat and I gave was packed full of theories and information. The professor said it was best he has heard. Come the conclusion, we generated a class-wide philosophical talk on what is consciousness and what structures contribute to it from a neurological perspective. Hell, I could go on and on about this. There are so many leading neurologists out to find the answer to this very question. Ramachandran, who is arguably THE leading neuroscientist, and who also works out of UCSD ;) , is on a quest to find what consciousness is. He believes that the brain is encoded just like the DNA double helix, meaning there is some hidden code that determines what structures are for consciousness and which are used unconsciously. Hopefully he won't find out by the time I go to off to grad/med school because I would love to work with him on it. Anyway, I thoroughly enjoyed doing that presentation, which makes me even happier knowing that what I am learning and on the path to becoming, is what I want. It seems such a daunting choice from the outside looking in, but from where I am sitting, there is nothing more rewarding.