Thursday 4 September 2008

Pic of the day: The ability to have thoughts completely unrelated to the environment seems to rely on a specific group of brain areas.

Default network, part I

Today I once again saw a mention of the "default network" in the brain, and this time I tried to not forget it. I believe this is in part an early effect of Mnemosyne, that I start to look more consciously on things I read: "Is this something I want to remember? Is this something I want to learn more about?" And in this case, it is.

The default network is a connection of several brain areas. In adults, it is active when we are awake but resting. It is associated with daydreams and the internal chatter in our minds. When some important task comes up, this network falls silent, or nearly so. Except in the elderly, especially with Alzheimers: There it becomes MORE active when they try to solve a problem. It is not clear whether this is a problem or a solution. (The same network is active when remembering from one's own life, even if one does so consciously.) On the other extreme, the network does not seem to exist in early grade school - those parts of the brain are not talking to each other.

I believe I read about this "default network" in connection with people in coma or minimal consciousness. These people do not seem to react to things around them, and from the level of brain activity it has been believed that they were less conscious than the deeply sleeping. But this may not be true for all of them. In a few such patients, the default network is functioning. When asked to imagine doing certain actions, they did not move in any way or show that they had heard... but the brain scans showed that the brain lit up as if they were actually doing those things. (Like walking around in their house.) Creepy!

Today I read about Zen Buddhist monks and other people. A group of each was told to perform a task. The monks quickly returned to internal quiet after performing the task, but the ordinary people took some time.

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It strikes me that the Default Network may be the one thing that can best explain the difference between me and other humans. It may also explain why I have changed over time, and particularly over the last few years. But is it becoming more active (like in the Alzheimers patients) or less?

A couple years ago I read on BBC's website that autists don't daydream. This fascinated me. In school, I did well partly because I was unable to concentrate on my daydreams as long as the teachers were talking. For me to daydream is not so easy: I tend to need to "pull myself together" to daydream, to consciously concentrate on telling myself a story which I "illustrate" by positional feelings rather than vivid pictures. I wonder if this is related to other traits I share with autists, such as an extremely low interest in socializing, and a sensitivity to light and sound, not to mention touch.

When I was a young man, I discovered meditation more or less by accident, although I read up on it and experimented more when I was told what it was. Could it be that I have a natural leaning that way because my "default network" is less active (or more? Probably less) or works in a different way from usual.

But regardless of whether I am slightly differently wired, it is possible to change the brain through training. This is a scientific fact. It takes time and the training must be regular to make a change, but even in adults there can be large changes. And there better be. There is an acute need for ordinary people to become more like me - but not all the way, otherwise the species would die out, I'm afraid!

These are just thoughts that came up quickly after reading a few small articles and abstracts on the Web. Hopefully I will remember to learn more about this - unless the internal chatter drowns it out and I forget this too.