Friday, June 13, 2008

I Think That I Shall Never See, A Brain as Pretty as a Tree

What if, sunlight to a tree, is as information to the brain? A tree needs sunlight to survive, to produce food. In response to this basic need, the tree spends a lot of its effort to maximize its ability to obtain sunlight. It does this by forming more leaves, and by spreading those leaves out at widely as possible to cover as much area as possible. Pushing this idea even further, to the extent that the tree covers a portion of area, that is the amount of sunlight it can absorb. Sunlight falling on other areas will be lost to the tree (albeit there might be secondary or tertiary transfer of energy via light reflection, diffusion, and other means). One important parameter that would determine the success of sunlight absorption for a tree would then be leaf surface area. Specifically, greater surface area would increase sunlight absorption rate.

Now, we project this idea onto the brain, of course being well aware that the brain is much different from a tree, although, probably not very very different. The brain is in the business of representing information. Its very function is the processing and retaining of all the information fed into it from the moment of its development. It would be interesting to pursue when this onsets, but that is a digression for later. Nevertheless, the brain develops in tandem with its experience with information. Some of that information is hardwired, or genetic. Some of that information is nurtured, or environmentally experienced. The role of each neuron then, in cooperation with all the other neurons in the brain, is to keep EVERY SINGLE EXPERIENCE, whether internal or external.

Why does the brain want to do that? Well, that's the same as answering why does a tree want so much sunlight for? We can only provide partial understanding here, because this borders on the domain of philosophical and religious pursuits. Biologically, a tree seeks sunlight as part of its nutritional source for the purpose of ultimately creating more trees. That is about as far as we can describe based on observation. This is, in a way, a tautology. Because what we impose as the purpose of the tree, is in fact, what we see the tree already doing. Therefore, such an answer may not satisfy some, but it is a partial answer at the least. Turning back to the brain, again, only a partial answer is given. The brain seeks to contain as much information as possible, because that's what is already observed that it is doing, and perhaps, this information helps the organism to survive, and to produce more organisms of this kind.

More importantly here, we shall consider how does the brain perform this function of representing as much information as possible. The tree does it by increasing surface area exposed to the sunlight. The brain's equivalent would be to increase the number of neurons it has, the connections between these neurons, the variability in the way these neurons can activate. Some smart person might be able to come up with an equation that tells us how much information a given brain with a given number of neurons and connections, and variability in activity, can hold. This could somehow be mathematically related to the concept of surface area...

However, there is a problem in terms of space. While the brain is fantastic and has way superior computational capacity, it is still finite. That is, there may come a time when a given person's brain can no longer process anymore new information. Maybe it has come already, just that we don't know it or that its not as big of a problem as we might think, given we have external aids for our memory now, through things such as computers, books, paper, language, and symbols. This finite capacity is indeed a problem, but our brains have a rather interesting way of solving it, at least to a great extent. Lets turn back to the tree for a moment, because its a greener thought. Lets say that to get more sunlight, the tree has two ways of doing it given a fixed amount of material. It can send more branches out with many leaves, or it can make fewer but bigger leaves. If it sends out more branches, it would have to content with using some of that material to make tree-parts that don't absorb sunlight (branches). If it makes bigger leaves, it may have to content with those leaves blocking each other out, since they will be close together as there are no branches to help spread them out. In the same way, the brain might have two ways of holding information within a limited amount of material. It can create more and more connections with more neurons, or it can use the existing neurons and connections in different ways. Here is where the tree analogy might break down. Unlike information, sunlight to a tree is a one-dimensional problem in the sense that it only needs to worry about expose area. Information, however, is obviously multi-dimensional, with auditory, visual, tactile, odor, taste modalities in the sensory domains, and countless of types of dimensions when you think about concepts and their associations, temporal information etc. Another dissimilarity between a tree and the brain is that most trees only make one kind of leaf, or grow with a certain fixed physical structure. The brain is able to flexibly use neuronal connections to group neurons in very dynamic ways. So, while a tree either has small or big leaves, the brain may use both small groups of neurons encoding some type of information, as well as bigger groups encoding other types of information.

The maximum surface area of the brain (meaning the physical ability of the brain to differentiate between its billions of states of activity using its neuronal connections), limits the total amount of different information the that brain can keep. This will be developed in later blogs. Here are some teasers. One brilliant way of reducing the space needed would be to encode information in terms of similarities and differences. And also, unlike a tree, the brain in the organism makes decisions about what the organism should do, affecting the environment and modifying subsequent experiences, as opposed to being completely at the mercy of the experiences.

Next time...."Similarities and Differences", and "The Brain, The Tree, Intentions, and Decisions".


  1. Oh my gosh, I cannot believe I just read all of that. You are truly my geeky friend. :) Good stuff though. Nice to see that you've finally updated your blogsite.

  2. Yeah, I can't believe you read all that either! One day, I shall write a book on nothing but if!