The following are bits of writing from many sources such as personal correspondence, posts to on-line discussion groups, notes, and occasionally even some journaling. All of this is informal in nature, but contains some interesting and/or useful information.

Where in your brain
[Posted to the neuroscience group on]
>Is this passage telling me that there is a part of my brain that tells me that my "soul" (so to speak) is inside my flesh and not inside that box of Swoops I'm holding in my picture?
Not exactly. It's just that you know where you are in physical space. Rather than the awareness of this, people general speak in terms of the sensory component, something called "proprioception" that monitors where your body parts are relative to one another. This is why you can put your arm over your head and know which direction you are pointing your index finger even though it isn't in your field of vision (unless you look up, of course).
Then there are "place cells" that keep track of where you are as a person. (I don't know if this awareness has been assigned a term yet; there isn't an obvious sensory component since this is achieved through vision whereas proprioception is accomplished via mechanoreceptors in your muscles). These cells fire up if you are in, for example, the corner of a room vs. the center of it.
No one has figured out how higher levels of awareness arise that let us interpret these signals. This is part of what consciousness is, and so far no one has even been able to satisfactorily define that concept, let alone to formulate an operational definition that would allow anyone to test hypotheses concerning the workings of consciousness.
However, if conscious awareness of where you are equates to having a "soul," then a few stiff drinks and you'll lose your soul. So the Baptists were right!

Where in the brain (cont'd)
[Posted to the neuroscience group on]
>Is there really a part of my brain that tells me that I'm sitting in the chair?
Yes. If you think/feel/sense/recall/etc. something, there's a part of your brain that is involved in it (and since most mental processes are multi-faceted, there is usually a system of parts coordinated in that process; see also "association cortex").
Most functions can even be localized with a high degree of specificity. Even the more general mental processes like memory or consciousness (whatever that is) still have a clearly physical basis as evidenced by the altered/reduced/eliminated states induced by trauma, injury, drugs, tumors, surgery, electrical/magnetic stimulation, or anything physical that touches them.

The fact that you are aware of your brain chemistry and can observe it objectively makes it an interesting phenomenon, so you appreciate its manifestation even though are are affected by it on a separate level.

Subjectivity in subjects
[Posted to the neuroscience group on]
One of my professors works with chronic pain using animal models. He admits that one of the frustrating things about research in his area is that you don't really know if the animal is indeed in pain. Unlike humans (who can at least use subjective assessments like Likert scales, etc.), you can't just get an assessment of the degree of pain to see if the phenomenon you intend to study and treat is even present in the first place.
Until we get a firmer grip on what an emotional or other cognitive state is in terms of neuroscience, there will always be a degree of uncertainty in much of the research conducted into problems like this.

[Posted to the neuroscience group on]
>Has anyone here heard about those who can't feel pain?
Yes. I have no idea what this is called, though. Apparently, it's quite rare.
>Or that they have a missing limb but it still feels like they still have it.
This is commonly known as a phantom limb. It comes from retaining the internal representation of the limb(s) and the fibers leading up to those representations (e.g., in the dorsal nuclei, thalamus, and, finally, in the somatotopic cortex). Those areas are still activated and have a limb (so to speak) long after the physical limb has been lost, although this does diminish with time depending on a lot of factors relating to brain plasticity (e.g., the age at which the limb was lost, etc.).
>Or that let's say when they're shaving they feel it on another part of their body.
This is called referred sensation. It's especially common for people to have referred pain, however. For example, when someone is in the beginnings of a heart attack, they typically feel pain in one arm. This is (thought to be) due to convergence of fibers from two regions. Unfortunately, the brain often misinterprets which region a signal is originating from, so you think the pain has a different cause unless there is strong evidence to the contrary (which doesn't change the actual sensation, of course).

My dichotomous mind
I took a "brain test." My scores were:
Left: 47.6%
Right: 52.4%
Visual: 47.1%
Auditory: 52.9%
These were about what I expected after the first few questions. I usually come out like this on these sorts of tests. The L/R and Vis/Aud dichotomy is largely redundant. The left side of the brain is responsible for language in all but 1% of the population. In fact, I amazed the students in the lab I teach the other day when I deduced that a student's grandmother was left-handed based on the symptoms she experienced following a stroke (language difficulty and left side paralysis).

More about the brain test and testing in general
I didnít re-attempt the test after the first time, but the comments were fairly accurate in my case. The more extreme you are, however, the better the accuracy because of what are called ceiling and floor effects. Once you reach a limit, you canít compensate for the effects. The reason why this test can report on people with a high accuracy is not so much because these questions tell a lot about your personality, but because they tell a lot about the about the way your brain is organized. From that, the leap into personality can occur. There has been an enormous amount of research into this area as organizations use it for placing employees in the best positions, etc. Schools are beginning to employ personality tests and the like for the purpose of finding the best means of assessing kids, the rationale being that the more appropriate the test, the better the school will look in terms of test scores.
An interesting extension of this field is the area of emotion intelligence (EQ, as opposed to IQ). This looks at people in terms of personal motivation, empathy, interpersonal skills, etc. This touches on something I alluded to earlier with respect to Robert Downey, Jr. and his infamous drug problems. All our experiences and much of our personalities reside in the frontal cortex. However, the pre-frontal cortex can over-ride intelligent decision-making and run a life into the ground through poor choices (which, most importantly, run counter to everything an individual may have been taught, believes, and professes publicly). This is the next frontier in psychology and especially with respect to pharmacology.

Still more about the brain test
C took the brain test and scored mostly right brain/visual, which is not especially surprising knowing her, but unusual given in her area of teaching. I probably mentioned to you that "Auditory" is a misnomer for what they are testing for; this test looks for language preference. Believe it or not, I tend to be more language-oriented than in most areas. For example, she teaches English mainly through literature, whereas the sciences often require very precise (and certainly specialized) use of words; and I tend to do better than average in this area. I drive my students crazy making revisions to their lab reports, and used to proof anything anyone in my lab wrote.

There are a lot of perceptual studies that show that people can pick up on little things that aren't quite right. For example, if you are shown a photograph of someone with the image reverse, you will notice that something is a little off. Similarly, they can make a perfectly bi-lateral image by duplicating one side of your face and flipping it. People look at those images and can't place it, but they know there's something different. On the other hand, I had a nose job and no one noticed. Go figure.

The Sixth Sense
If you want to learn about a real "sixth sense" we all have (no, not the dvd in your living room), then you might want to read this article:
Brown JW, Braver TS. Learned predictions of error likelihood in the anterior cingulate cortex. Science. 2005 Feb 18;307(5712):1059-60.
Here's the abstract:
The anterior cingulate cortex (ACC) and the related medial wall play a critical role in recruiting cognitive control. Although ACC exhibits selective error and conflict responses, it has been unclear how these develop and become context-specific. With use of a modified stop-signal task, we show from integrated computational neural modeling and neuroimaging studies that ACC learns to predict error likelihood in a given context, even for trials in which there is no error or response conflict. These results support a more general error-likelihood theory of ACC function based on reinforcement learning, of which conflict and error detection are special cases.
This story was carried by a number of sources in the popular press when it first broke last February. Here's a good one:
Also, Malcolm Gladwell's latest book "Blink" deals with a lot of the rapid and completely unconscious processing that looks to us to be intuition or something else paranormal (Just to ruin it for you: No spirits were required). He's very readable, and it's good stuff. There are sample chapters on his site as well.

>I'll probably get the wisdom teeth taken out soon, though. :)
I didn't have a bad experience with this at all. In fact, I has a good time on the gas. I remember laughing at some really strange stuff that was going on. For example, two of the nurses (assistants?) were talking. One was telling a story about how she and her brother ran into one another at a wedding the previous weekend and they were very cold to one another. For some reason (okay, it was the gas), I thought this was possibly the funniest thing I had ever heard, but I kept trying not to laugh because I wanted them to continue with this "hilarious" story.
I also remember looking down at my feet, only I couldn't see them since my head was pretty far back in the chair. I looked down and saw the wall in front of me. Since the wallpaper was vertically striped, I was really confused because my show laces were horizontally striped, so what was going on? It finally clicked that I was looking at the wall, and I started laughing again at that. Fun stuff!

What's PPI?
There is a mental phenomenon known as PPI that most people have, but is lacking in people with ADD/ADHD. Here's a (relatively) brief overview I wrote up for another discussion group a while back. This is fairly technical, but give it a read (all the way through this time, guys!). I think many of you will find it helpful.
PPI (short for "Pre-Pulse Inhibition") is a feature absent in a lot of mental disorders where afflicted individuals have trouble filtering out intense sensory stimuli (e.g., loud noises, bright lights). Some of these disorders include ADD/ADHD, schizophrenia, autism (including Asperger's), and OCD, among others.
Where the name comes from is that, in most individuals, a "warning shot" (i.e., pre-pulse) will prevent a second, larger stimulus from making them jump when it arrives moments later. For example, if I say "Boo!" you might jump. But if I say "boo" (normal speaking voice) and then give you the big scare a second later, odds are it won't spook you as much. This is not the case in individuals with the disorders highlighted above, hence ADHD kids attend to the least distraction, autistic individuals are bothered by physical contact and deviations from routine, and so on. I'm sure many of you reading this can think of examples of sensory stimuli that you could not filter out such that it either became painful or at least intrusive enough to keep you from concentrating.
Basically, it's like having a hangover or some forms of migraines in which sensitivity to stimuli is increased... only it's like that all the time. Some people who have this to a large extent find that they are irritated by loud noises and/or bright lights more than their peers. (I'm one of these people, incidentally.)
As for what you can do about it... that's a tougher problem. If it is part of a larger condition that can be diagnosed (e.g., ADD/ADHD), doctors can then treat the big picture and (hopefully) deal with that component in connection with the rest. However, there are certain modifications you can make yourself like avoiding clubs with loud music (try a coffee house instead?) and carrying a pair of ear plugs. That doesn't look cool, but if you're going to be miserable otherwise, which would you prefer? I would also suggest explaining what PPI is to your friends so they won't think you're being rude if you have to distance yourself from unbearable stimuli.
That's hardly the last word on the subject. I'm sure there is much better advice out there, but this is a framework for understanding what you're dealing with.

Sensory gating
Concerts don't bother me so long as I have earplugs handy. If it is a constant level (albeit a loud one) I can adjust. However, there's a neurologic ability most people have that I don't: pre-pulse inhibition. "Normal" people can filter things to a certain level after their first exposure, but I can't. It's a sensory gating phenomenon, and it's one of the core things in autism than makes this kids freak out when they are exposed to unexpected stimuli.
ADD/ADHD kids have the same problem, although they are "driven to distraction" rather than annoyance in most instances. That being said, extreme levels have the effect on them that you usually see around me. I think my dad has the same problem because he is bothered by a lot of the same sounds as I am, particularly kids screaming spontaneously and unnecessarily. He and I both want to kick them in the teeth when they pull that shrill, obnoxious shit while standing right next to you.
Whereas most people are just annoyed, it is not a very pleasant experience when you can't filter it out enough to make it less than outright painful.

Cosmic experience
I know a lot of people have "cosmic" experiences on LSD. I had one of those momentarily as a result of sleep deprivation. This was when we were still lying in Folsom, and I had been out all weekend camping with a couple of friends. We stayed up all night running around the woods and riding bikes on the highways (Statistically I should have been dead sometime in the early '90s), so we never got any sleep. At one point we went over to the home of one of my friends we were out with so he could pick something up. Since I was all muddy, I laid down on the patio and was halfway asleep within seconds. My eyes were barely open, and I saw a little string dangling down from the cushion on the seat of one of the patio chairs. In my mind that string was the most important thing in the universe. I couldn't tell you now what the hell I was supposed to do with it or how to tap into its incredible power, but it was the culmination of billions of years of work that would save us all. Or something like that. I woke myself up laughing as I realized what I was thinking lying half-asleep on a patio in Folsom all covered in mud.

Copyright Alexplorer.

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