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Name: N Scherer
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How does the brain work?



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Mechanically or conceptually? A subway system works mechanically by cars on steel wheels, rails, and 500 volts of electricity shunted hither and yon on overhead wires. Conceptually though it's a widget to get folks from where they live to where they work, and it works by figuring out the paths they take, assigning trains to those routes, and discounting fares off-peak to even out the rush-hour crowds.

Mechanically the brain is billions of cells called neurons that can produce little bursts of electricity that can be passed from cell to cell. (Brain neurons are densely interconnected.) These bursts produce weak electric fields at the surface of the head that can be recorded, hence the EEG ("electro-encephalogram", Greek for recording (gram) of head (cephalus) electricity, aha.) Coarse features in the EEG are found to be related to broad categories of brain activity: larger, slowly-varying electric fields indicate sleep, smaller, faster-varying fields alertness, etc. More subtle measurements map increased electrical activity in certain *regions* of the brain when people remember, speak, or blow their nose, and direct electrical stimulation of certain areas of exposed brains produces sensations, movement, memories of the Kennedy Administration, etc. Thus the wide assumption is that it is the pattern of the electrical bursts of the neurons that constitute thought, along with perhaps chemical changes in each neuron to account for memory, learning, personality and other slowly-changing brain behavior. An article in the April 1994 issue of "Scientific American" details some recent nifty experiments on mapping brain activity and correlating action and thought. Also consider the books of Oliver Sacks on brain dysfunction.

You'd think knowing how the brain works mechanically would tell you ipso facto how it works conceptually. Alas no. Conceptual understanding of brain function is much more incomplete. Doubtlessly the most influential thought on thought (argh), and a major force shaping social currents in the 20th century, is the hypothesis of the division into conscious and unconscious mind. Much is known about learning and problem-solving techniques of the conscious mind, and its organization of basic thinking tasks (e.g. remembering, planning, perception), but we don't know the mechanics of, and cannot duplicate ourselves, the two most outstanding features of the mind: its ability to respond originally, i.e. create, and its self-awareness, i.e. consciousness. For amusing essays on the latter consider "The Mind's I" by Daniel Dennett and Douglas Hofstadter, or the short stories of Stanislaw Lem. One of the most popularly influential recent books is Julian Jaynes' "The Origin of Consciousness in the Breakdown of the Bicameral Mind," which has left us with left- and right- brainedness on the brain. My favorite paradigm is that *intelligence* consists of having a mental model of the world in which to try out new ideas for future action off-line (which as Karl Popper says enables "our hypotheses to die in our stead"), while *consciousness* consists of including in that mental model a little model of *ourselves* as well. To be conscious is then to be able to watch yourself watch the world. Yow.

Christopher Grayce



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