How do drugs affect the mind? (or, what is the nature of consciousness?) pt.1

The other day I stumbled upon (via erowid) a pretty interesting online book about the psychological effects of marijuana:

"On Being Stoned" by Charles T. Tart Phd.

I haven't read the whole thing yet, but so far the chapter on vision is of particular interest, as it brings up larger questions of how the mind works. In the summary of Chapter 6 Tart writes:

In general, the specific changes in visual perception brought about by marijuana intoxication may be seen as particular manifestations of a general change in what we might call the visual pattern-making process. It is common to assume that we passively "see" what is out there, that the qualities of the visual world are inherent in the physical properties of objects and space. Modern psychological investigations have made it clear that seeing is a very active and complex process in which we construct the visual world from the flux of visual sensations reaching us. That is, patterns, forms, objects, recognizable people, etc. exist in our minds as a construction from visual data. We are so used to doing this automatically that it seems as if the visual world were given. This active nature of visual perception is true of all sensory modalities.
The patterns that are formed from visual data are organized into a degree of complexity and familiarity that is optimal for surviving in the world around us. Detecting a potential predator concealed in some bushes has survival value; seeing a potential predator in every ambiguous visual input is not conducive to survival of the organism. Thus we may conceive of some optimal level (actually a dynamic range) of patternmaking activity, of organization of ambiguous (and not so ambiguous) visual data into meaningful percepts. Raise this level too high and we have illusion or hallucination. Lower this level too much and we have stupidity.

In my opinion this is a highly accurate description of the visual experience while high, but is also an accurate description of the experience as a whole; the same logic can be applied to the other senses and, more importantly, the mental state. Since marijuana is a "conscious-altering drug," I think that such an apt description may help describe what, exactly, consciousness is.

Neuroscientists and philosophers separate the mystery of consciousness into two problems: the easy problem and the hard problem. The former has to do with the specifics of the brain (i.e. how consciousness is possible) and deals with the hard science of describing how consciousness can arise in living organisms. It's just a matter of time before it is figured out from the mounds upon mounds of data that has been (and will be) collected regarding the brain. The latter is a bit trickier (hence the name "hard problem"). How do we define - or explain, for that matter - the subjective experience of consciousness? All we know about it is that it exists. It exists, and we are experiencing it. You know that you're conscious (or, at least I hope you do), but the second you try and describe it you can see why it is so problematic for scientists.

Jeff Hawkins (author of "On Intelligence") proposed an interesting model of consciousness that, coincidentally, ties in with Tart's observations of altered consciousnesses. Hawkins proposes that the mind is really a hierarchical temporal memory (HTM) processor. In English: the brain works by processing memories of previous experiences and uses them to predict the future.

To put this in neural terms, a certain stimuli (light) may strike the eye, causing the the rods on the cornea to fire, sending an impulse to the brain; this is known as sensation. Perception occurs when the brain puts all this together into something that it can understand. According to Hawkins, the mind is organized into layers of complexity. The layers are metaphorical, but the connections of neurons that they represent exist in the brain. Keep in mind that when I say connections, I mean many connections. One neuron, for example, has somewhere in the neighborhood of ten thousand neural connections. The layers representing simple constructs (such as lines) are on the bottom of this hypothetical hierarchy and get more and more complex as you go up the hierarchy. I won't explain how action potentials work, but when the eye presents the brain with stimuli of a line, the connection of neurons that represent the line star firing.

If three lines are presented (representing the letter F) then the three connections will will trigger another network of connections on a higher layer that represent the letter F. Since the brain is extremely connected, the simple concept of the letter F may trigger other ideas, especially if the letter F is significant in some way. If it is presented with other letters, for example r-a-n-z-K-a-f-k-a, then it elicits the mental representation of the author and his work, perhaps more. The interesting thing, as far as Hawkins is concerned, is that you would still think about Franz Kafka if we took the last a out. All this is, of course, simplified, but the basic idea is that the mind works as a hierarchy, with the simple ideas on the bottom and the more complex ideas around the top. Furthermore, the entirety of the simple ideas are not needed to stir up the complex idea.

This is all an unconscious process that relates to perception of senses, specifically. But I see this is being applicable to abstract thought as well as concrete perception. If our minds are arranged in this fashion, then who's to say that we don't organize our subjective universe in the same way? As we start to get more and more complex with categorizations, we eventually reach the level of abstract concepts.

More on that in the next installment...