Matter and consciousness; the brain and the effects of the brain, understanding this has been a fundamental task for philosophers for millennia, whether the souke of Aristotle, Cartesian dualism, Kan'ts transcendental idealism, psychology or neurology, it has never abated. To understand how the brain works is to understand the microscopic and macroscopic functioning of the integrated system of neurons, and to understand the brains significance is to ask as to the nature of significance itself.
First a few fun facts about the brain.
The brain is composed of roughly 200 billion neurons, each with between 1 and 10,000 independent connections.
The amount of potential particles in the universe is 1 x 10e79 and the amount of potential pathways in the human brain is 1x10e1,000,000
What we are dealing with here is the most complex thing in the perceivable universe.
Now for a brief summary of the working of the brain and why this is inadequate to explain the fact that we are conscious.
The basic neurone, though there are hundreds of subcategories, basically function on the same basic need to propagate an electrical impulse, and modify their own structure to modify the pulses which they give.
The cell itself is composed of dendrites (which for the most part receive signal) and axons (which for the most part send signals), they are connected, apart from motor neurones in the peripheral nervous system and a few others, at the synapse.
The electrical signals in the brain work different from a current, as in the displacement of electrons down a conductive material, they work based on a charge created by positively charged ions which surround and lie internally to the cell. Chloride, Sodium, Calcium and Potassium are the principle ions. We will take the basic model of Sodium and Potassium. Sodium is in high extracellular (outside the cell) concentration, and potassium is in high intracellular concentration (inside the cell), this establishes a concentration gradient, essentially meaning that the sodium wants to enter the cell as there is a low concentration. When the electrical charge hits the cell membrane (the outer edge of the cell) it opens gates made of proteins which are selective to sodium ions, and allows the influx of sodium. Now remember these are all positively charged ions, so once sodium and potassium are crowding the cell, they crowd it with a positive charge, which is then able to flow into the axon. Then ion pumps selectively remove ions reestablishing the resting potential (they charge needed for the cell to be considered off). Once at the synapse hormones (serotonin, dopamine, noradrenalin, cannabinoids, glutamate and GABA and 100's of others) are released into the synaptic cleft, which is the gap between the axon and the dendrite. Depending on the chemical the result can be a high stimulation, with repeated pulses, a singular pulse, or it can elicit no pulse. The former two are excitatory chemical reactions and the latter is inhibitory.
Bare in mind this is a very gross description for the purposes of this article, though this is the basic model there are far many more facets to the human microscopic brain, which will fit nicely with my final point.
The brain is then further organised into functional segments, with different regions performing different functions. We are able to understand these different functions by analysing lesions to the brain through accidents, and the behaviour they cause. A few examples are if the corpus callosum (the large bundle of axons which connects the two hemispheres of the brain) are severed then the person will developed two separate personalities within the same brain. Another is called Kapkra syndrome, a syndrome where someone suffers a lesion to the fusiform gyrus, which is along the visual pathway and sends its information to the amygdala (where we get our basic emotional response of fight or flight) before going to the visual cortex and then to be processed by the rest of the cortex. If their is a lesion between this and the amygdala, after, say, a head trauma, the person will be able to recognise their mother however they will believe it to be an impostor! This is because the line has been severed to the emotional response, but not the processing centres of vision, which will piece together a more abstract familiarity from memories. This was tested with a Galvanic skin test, where someone puts electrodes on the palm of a patients hand and measures their emotional reaction through tension and sweat. Everyone gets a reaction when they see their mother, people with this syndrome however do not.
Thus impairment in the brain, does stop the functioning of aspects consciousness. The fundamental question however, despite the wealth of complex and esoteric knowledge on the subject, still remains. How do these series of chemical, ions, proteins, electromagnetic interactions, go from that, to you sitting there reading English on a computer, trying to figure you just what it is i'm getting at. There are a multitude of different processes in different places, but not matter where you go you are going to be using the same basic matter.
Consciousness is something more surreal than we may give it credit for. There must be something else, and thus comes from one of the most empirical people you could talk to. If we reduce the human brain to its component parts we get a series of chemicals from the table of elements, no more than 10. All of these, and the electricity, somehow create the plurality of consciousness. If we reduce consciousness down to its component parts we are left with a sea of letters, potential sounds, colours, tones, shades, words, emotions, desires, beliefs, reasoning, logic, notes, rhythms, pain, discomfort, anger, jealousy, lust, pride, sadness, melancholia, and the list goes on and on, and all that creates these is a few basic elements and electricity. From this we should conclude that though they are inextricably linked, matter and consciousness, they are still different phenomena in the universe.
My Big TOE by Thomas Campbell is a great insight into this, this is from a well accomplished physicist who under the most controlled conditions possible has had outer body experiences, shared them with his son and co workers and who has documented his times traversing consciousness. I first heard of him giving a lecture at the London School of Economics. He never once speaks of anything dogmatic, but combines his theory on consciousness with the already established theories of quantum mechanics and relativity and has attempted to combine them into a complete unifying theory, something which was once attempted by einstein. It gives some food for thought, ask yourself, just what is the chemical composition of green, not wavelengths and rods and cones, but that very sensation of seeing green, why is it that way? Is green another part of a universal force, the existence of which we don't yet understand?