Word: neuronal
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Dates: during 1960-1969
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Study in man is vastly complicated by the fact that the human brain contains an estimated 10 billion nerve cells called neurons, and another 100 billion of a second type called glial cells. The fluid bath in which they are suspended is an important element in their electrochemical interactions. Moreover, said Sweden's Dr. Holger Hydén, one big neuron may have on its surface as many as 10,000 points of contact (synaptic knobs) with other neurons (see chart). But by means of exquisitely delicate instrumentation and an electron microscope, Dr. Hydén has discovered that...
Learning About Life. Most scientists now agree that too much was made in the early days of the apparent similarities between computers and the human brain. The vacuum tubes and transistors of computers were easy to compare to the brain's neurons-but the comparison has limited validity. "There is a crude similarity," says Honeywell's Bloch, "but the machine would be at about the level of an amoeba." The neurons, which are the most important cells in the brain, number some 10 billion, and each one communicates with the others by as many as several hundred routes...
Stimulation, they found, resulted in a marked increase in the neurons' content of enzyme proteins, while the glial cells showed a corresponding drop. The glial cells behave like the self-sacrificing wife who eats mostly potatoes and gives the high-energy meat to her ditchdigger husband. The "information" contained in the protein which the neuron forms, reasons Hyden, becomes the impulse that the neuron sends along the filaments to other neighboring neurons...
Modified Proteins. The higher brain functions of memory and reasoning, Hyden hypothesizes, are achieved by the way the neuron alters the protein it forms. Each neuron contains millions of molecules of ribonucleic acid (RNA). Each of these molecules is chemically keyed by the arrangement of its internal building blocks. These molecules dictate, in accordance with their keys, the nature of the proteins that the neuron forms, in cooperation with the glial cells. The modified proteins are the chemical representations of thoughts...
...impulse caused by the ear's hearing "concert A" scurries from cell to cell until it finds those containing RNA molecules already keyed to respond to that note, and it is this chemical response that constitutes recognition of the note. The average human brain has ten billion neurons, so the number of possible permutations is astronomical. Further, said Dr. Hyden, this theory explains why neurologists have been unable to find precise centers in the brain for most higher mental functions: through its content of many imprinted molecules, each neuron may participate simultaneously in many neuronal networks-and therefore...