Friday, January 27, 2012

Brain waves

I have been thinking about my brain, although actually my brain was thinking about itself. My brains "sees", "hears" "smells" and "feels" for me. Other parts of my body do the physical work, eyes, ears (or rather the hearing structures inside the ear), nose and hands. They send impulses through the nerves to the approriate part of my brain where they are interpreted. But, there is another part of my brain that constitutes my "personality", or "character', and I put these in inverted commas because it is difficult to define them, they are not made up of the portions of the brain that respond to purely physical stimuli from the outer world, they constitute the "self.". In what way do "I" think or does my brain think. My mind is a manifestation of the electrochemical workings of my brain.

I began to think about this problem, of the identification of the workings of the brain, when I had a conversation with my oldest grandson, who has decided he wants to study psychology. I told him about Broca's brain, that part of the brain that was first identified to have a specific function, namely the ability to speak. French physician Paul Broca was the first to recognise in the mid-nineteenth century that growths in this part of the brain caused aphasia, the inability to speak. In 1997 Carl Sagan wrote a book entitled "Broca's Brain" that addressed these issues.

When there is physical damage to the brain there are changes in human function. For example, multiple sclerosis is caused by the accumulation of sclerotic plaques consisting of amyloid protein that develop in the brain and cause loss of motor functions. Parkinson's disease results from functional damage to a particular locus of the brain, and many neurological diseases result from demyelination of the nerves. Myelin is the substance that is contained in the sheath that surrounds the nerve axon that acts as the "wire" that transmits the nerve impulses, and myelin is like the insulation surrounding the wire. If it is removed or damaged then the electical impulses cannot be transmitted correctly leading to dysfunction. Also in Alzheimer's disease there are visible nerve "tangles" in the brain that result in loss of function, most notably loss of memory.

So far no one has been able to locate the actual locus of memory in the brain, and there are theories that memory results from distributive networks of neurons in the brain. However, that seems unlikely, since memory is a human's most personal attribute and its origins must be a carefully protected. When damage occurs to the brain there is concomitant loss of function, we do not know what happens to the memories that are "lost" they are gone forever. Likewise when the brain dies, all that it contained when alive is lost and brain death is synonymous with human death. So when the brain dies nothing remains once consciousness is lost. Perhaps in the future a person's memories could be recovered from their dead brain. That might be the first step to immortality.


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