No organ in the human body is more fascinating than the brain. Clench your hands into tight fists and bring your hands together, palms facing inwards. The structure so formed represents the approximate size of the brain. Superficially, the brain is a soft organ with a greyish appearance that is highly wrinkled on the outside. Within this organ lie approximately 100 billion to 1 trillion neurons (nerve cells) connected to each other by an even greater number of processes called axons and dendrites. Surrounding these neurons are large number of support cells called glia.
The complexity of the brain is defined not only by the total number of cells, but also by the number of connections made between neurons. These connections or synapses are the sites of communication between cells and it is at these sites where much of the modulation of the brain's electrical activity occurs. This modulation of activity is what makes the brain a highly adaptable organ, thereby allowing the process of learning to occur.
If your brain were to behave like a simple serial computer, such as the one you are probably using to view this file right now, then it could not possible function fast enough to process all of the information received. Nor would there be sufficient space in your brain to house all of the memories which you have. Imagine that each neuron in the brain were to house one unit of memory (whatever that is). Then the brain would be able to house only 1 trillion bits of information at most....surely not enough to create the individual that you represent, your memories, your emotions, your character traits and those other features that go into the construction of your total personality. Furthermore, how would you construct a conscious self which is capable of thinking about its own thought processes with such a simple machine? For many philosophers such as Descartes, it was inconceivable that the mind could simply be the product of physical processes. An yet, this concept is implicit in modern neurobiological research.
there are clues to many of the questions posed above. We now have some
indication of how the brain is built and what principles underly certain
basic thought processes. That is not to say that we have a complete picture
of how we think. Nonetheless, it is clear that the brain functions through
a simple set of rules. These rules define a supercomputer which is far
beyond what modern technology can build today...a massively parallel neural
network. It does not seem inconceivable that, on the basis of these rules,
we cannot one day comprehend most aspects of mental function.