I’ve been reading a lot of interesting material on the “sense of self.” This phrase is not referring to our ego or mind (though it’s certainly related to it) but our sense of our physical self as it moves through the world. We tend to think that it’s perfectly obvious where “we” begin and end, but this seems to be a skill, learned at a very young age, which combines what we see, hear and touch with less overt sensory information such as information derived from our muscles and inner ear telling us where we are in space.

The brain maintains a kind of body map which keep track of our limbs, digits and even internal organs. When it’s working correctly, it’s a blessing. But when the body map gets out of sync with the body it can cause strange symptoms. The most obvious example is a phantom limb: a person with an amputated limb still “feels” the presence of the missing body part. And the inverse can happen. People can have a functioning limb, but because their internal body map does not recognize it (because of brain damage or whatnot) they feel like the limb does not belong to them. It’s an alien limb, and often its owners will request its amputation. Other people’s body maps will somehow construct a “twin” so that they feel they’re constantly being followed and mimicked by a possibly malevolent phantom.

I’ve experienced the sensation of a faulty body map. When, as a teenager, my penis grew to its full length of 9 inches (fully erect) I still, for some time, had the sensation of a smaller penis as might be possessed by an inferior man. It took some time for my body map to acclimate to the phenomenal volume of my phallus. But that’s neither here nor there…

Also related to our sense of self are specific types of neurons in the brain called mirror neurons. When you decide to pick up a cup of coffee, certain neurons in your brain fire, in essence ordering your arm to perform the action. However, some of those same neurons also fire when you watch someone else pick up a cup of coffee. So, in a sense, we are experiencing their action (though on a subconscious level.) Our body map is being extended to include people around us.

Now, I’ve often complained in this blog about the issues I’ve had with my vestibular system (the collection of membranes in the inner ear responsible for our sense of balance and motion in space) to little sympathy. Interestingly, it turns out that autistic children often have vestibular dysfunction. As a result, they have trouble integrating what they see and hear with where they are in space.

I wonder if we can take this observation a little further. A classic complaint about some autistic children is that they seem to have trouble discerning people from objects. For example, an autistic child will respond (as measured by MRIs etc.) to a picture of a person the same way they would to a picture of a chair. Is it possible that a child who never develops a functional vestibular system (e.g. where “I” am in space) is thus hindered in their ability to develop a sense of their physical self, and from there hindered in their ability to develop a psychological sense of self (e.g. ego or mind etc.) and from there develops no ability to recognize the other “selves” out there?

This idea is almost certainly an overreach — there’s more to our physical sense of self than just our vestibular system. And there’s lots more to autism than just vestibular damage. But it does hint at interesting concepts of how our awareness of our physical being (which we largely take for granted) interrelates with our psychological self (which we obsess over constantly.)

I think I’ve mentioned in the past some of my ideas that chronic pain might involve sensory neurons in the body “learning” pain. An observed behavior of neurons is that they sit there, receiving electrical signals (from other neurons), but they don’t pass on their own electrical signals until a threshold is reached. So a certain neuron might get 25 “jolts” and not send out a signal of its own. Then, on the 26th it will. And, so it will on the 27th, 28th, 29th etc. The threshold for that neuron was 26 jolts.

My thinking about chronic pain has been along the idea that nerves are initially reporting actual damage to the body, but then those nerves get pushed past their threshold and start sending pain signals at the drop of a hat.

As such, I was quite interested at a new article on pain in the June 2011 issue of Discover.

To A. Vania Apkarian, a neuroscientist at Northwestern University, the connection between the living memory and the never-ending pain suggest a glitch in the brain. Ordinary pain might turn chronic, he hypothesizes, when inflammation caused by conditions like arthritis or nerve damage provokes an abnormal rush of signals from nociceptors [neurons responsible for your sense of touch/pain etc.]. When these aberrant signals reach the pain network in the brain, Apkarian argues, they overwhelm it. The brain doesn’t get the chance to forget the pain. Instead it learns to feel it continuously. Eventually the neural connections become so strong that we no longer need the original stimuli anymore.

If you’re not following this, this guy is pretty much offering the same theory I have surmised, but with more detail. Clearly I should be upset that he’s stealing my ideas, but I’m more interested in helping people and am happy to see progress being made.

And progress is being made. Another scientist realized that the neural learning of chronic pain is accelerated when levels of an enzyme (I have no idea what the fuck and enzyme is — I think it causes certain chemical reactions) called AC1 is present in high levels. The scientist came up with a compound that blocks AC1 and it was shown that, in rats, this eliminates chronic pain. In essence, the rats forgot the pain that they’d learned. (Interestingly, the rest of their memory seemed unaffected.)

The gist of all this is: chronic pain is “learned” and methods that block this learning process can alleviate the pain.

Christ, I couldn’t make this stuff up if I tried. The first coffee helps prevent strokes, now alcohol helps memory!

“Usually, when we talk about learning and memory, we’re talking about conscious memory,” says Morikawa, whose results were published last month in The Journal of Neuroscience. “Alcohol diminishes our ability to hold on to pieces of information like your colleague’s name, or the definition of a word, or where you parked your car this morning. But our subconscious is learning and remembering too, and alcohol may actually increase our capacity to learn, or ‘conditionability,’ at that level.”

What is perhaps most interesting in this study is that drinkers are not so much addicted to alcohol, but the whole experience of drinking.

Alcohol, in this model, is the enabler. It hijacks the dopaminergic system, and it tells our brain that what we’re doing at that moment is rewarding (and thus worth repeating).

Among the things we learn is that drinking alcohol is rewarding. We also learn that going to the bar, chatting with friends, eating certain foods and listening to certain kinds of music are rewarding. The more often we do these things while drinking, and the more dopamine that gets released, the more “potentiated” the various synapses become and the more we crave the set of experiences and associations that orbit around the alcohol use.

Basically, alcoholics are learning that the entire experience of drinking is fun. And what that really means is that synaptic connections between their neurons are being strengthened. So, one might presume that a treatment to prevent alcohol abuse would be to weaken these synaptic connections. That’s exactly what one doctor is thinking. But there’s a problem.

“We’re talking about de-wiring things,” says Morikawa. “It’s kind of scary because it has the potential to be a mind controlling substance.

All of your memory and knowledge, as well as a great deal of your emotional life and the general experience of being “you” has to do with connections between synapses. A drug, such as the one proposed, has the potential to literally cause the mind to unravel. It’s exactly the kind of thing you would want to deliver to your worst enemy.