Jun 4, 2008

What "consciousness" actually is !

In spite of all advances, neuroscientists still do not understand at all how a brain (the squishy agglomeration of tissue and neurons) makes a conscious mind (the intangible entity that enables you to fall in love, find irony in a novel, and appreciate the elegance of a circuit design).
Even when we dream, we are virtually disconnected from the environment—we acknowledge almost nothing of what happens around us, and our muscles are largely paralyzed. Nevertheless, we are conscious.
Indeed, the more you learn about brains, the more you may wonder how the damn things work. And in fact, sometimes they don't. They succumb to schizophrenia, bipolar disorder, depression, Alzheimer's disease, and many other disorders that resist explanation and treatment.
Many neuroscientists do assume that, just as computers operate according to a machine code, the brain's performance must depend on a “neural code,” a set of rules or algorithms that transforms those spikes into perceptions, memories, meanings, sensations, and intentions. If such a neural code exists, however, neuroscientists still have no idea what that code is as our brains are extremely adaptive and can accumulate every single bit of possible information.

One type of such codes might be a temporal code, in which information is represented not just in a cell's rate of firing but also in the precise timing between spikes. For example, the spike sequences 010101 and 100011 have the same number of 0 and 1 bits. But a may have different meanings because the bit sequences are different. Such temporal coding would boost the brain's information-processing capacity close to the Shannon limit( the theoretical maximum that information theory allows for a given physical system).
Sometimes they involve the correlated firing of many neurons. In which our recognition of, say, an animal emerges from competition between large populations of neurons representing different memories: Dog? Cat? Rat? The brain quickly settles on the population that most closely matches the incoming stimulus.
In humans and animals, we know that the specific content of any conscious experience—the deep blue of an alpine sky, say, or the fragrance of jasmine redolent in the night air—is furnished by parts of the cerebral cortex, the outer layer of gray matter associated with thought, action, and other higher brain functions.
So can we now say that someday we will get the codes of consciousness and will make conscious machine by reverse engineering the brain ! Some scientists say that our level of consciousness has to do with how much integrated information we can generate. That's why we have a higher level of consciousness than a tree frog or a supercomputer.
Some of the most brilliant minds in human history have pondered consciousness, and after a few thousand years we still can't say for sure if it is an intangible phenomenon or maybe even a kind of substance different from matter. We know it arises in the brain, but we don't know how or where in the brain.