Complex Complexity!

One of the things I’ve often been fascinated by in Neuroscience is the way that the brain actually functionally creates our experience as humans. This subject is, amusingly enough, not really addressed by contemporary Psychology. We look at some really behavioral topics, like Personality or Social interaction, and a lot of really technical, fundamental characteristics, like the action of neurons and synapses. We even know something about how each brain area contributes to a larger design of function, and often how we as humans are likely to react in a given scenario. But how does all of that fit together? By what means do I make decisions and interact with my world? When I’m doing something complex, like fencing, I am coordinating a series of reactions to outside stimuli that are extremely complex both in contemplation and execution and which, of course, require many different brain areas.

What I’m talking about here is something called an “emergent characteristic,” which is put simply a functionality that arises out of a system of simple parts that no single simple part can replicate. In this context, it’s the idea that a bunch of neurons acting together can form a pattern and when patterns are combined they form a brain state consistent with a thought (or multiple co-existent thoughts). Such a system must exist in some form, because what we know of individual neuronal action is not sufficient for us to construct a complete model of human function. We can describe reflexes, which are relatively simple interactions along a single chain of neurons. We run into trouble, however, when we try to look at complex interactions in the brain.

Last Thursday I started thinking about this concept, and just today I found the perfect article (Chialvo, 2010) to supplement my own thought. It’s attached, and you can certainly look through it if you want, but I’m happy to summarize the most important parts.

The first piece of nifty evidence for a emergent characteristic is called a neuronal avalanche, which is a process somewhere in between individual neuronal firing and whole-brain EEG patterns. When one neuron fires, it often causes many others to fire but it is relatively unlikely to cause a larger chain reaction. The researchers (Beggs & Plenz, 2003) did some complicated math that unfortunately is a bit beyond me, and came up with functioning consistent with a critical branching process (one that allows for the creation of complexity, and if that doesn’t make too much sense read this: http://en.wikipedia.org/wiki/Self-organized_criticality). It is, in other words, a process that could create the sort of functioning that we’re looking for to explain conscious thought and complete brain understanding! Cool! Even if the math is complicated and highly theoretical.

The author also mentioned an fMRI study where, if you take a series of scans of the brain, you can mathematically link your pictures into what amounts to a video of brain activity. When that is done, you can watch clouds of activity pass through relevant brain areas in a manner consistent from individual to individual.

Now that I wrote all of that up, I realize that it was even more complicated than it looked when I read it. Suffice to say: the author likes the math, but finds evidence for emergent characteristics that could function as a substrate for a functional understanding of thought. The author also agrees that this sort of thing is entirely necessary to fully appreciate how we think and interact with the world.

http://www.nature.com/nphys/journal/v6/n10/full/nphys1803.html

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