The Brain at Work

How does the brain go about its intricate business? Last week Dr. Hudson Hoagland of the Worcester Foundation for Experimental Biology summed up recent theories on the brain.

Yes or No. The basic unit of the nervous system, said Dr. Hoagland, is the neuron or nerve cell. When neurons are stimulated, a wave of electrical energy passes along their interconnecting fibers. When it reaches the "synapses" where the fibers touch those of other nerve cells, it may pass the impulse along. Or it may not. This "yes-or-no" response of the neurons, Dr. Hoagland believes, is the basis of brain operation. Certain calculating machines work the same way, their vacuum tubes or relays responding or not to the electrical impulses that reach 'them.

One of the brain's most baffling qualities--memory--began to be explained, said Dr. Hoagland, when it was found that many of the brain's neurons are arranged in closed chains. An impulse can move around the chain, "firing" one cell after another. When it gets back to its starting place, it can make the circuit again & again. These circulating impulses, thinks Dr. Hoagland, are the basis of memory.

Waves of Memory. But how does the brain call up these "memories" when it wants them? Neurologists have known for many years, said Dr. Hoagland, that under certain conditions (when a person is awake with his eyes closed) waves of electricity, about ten a second, pass rhythmically over the top of his brain. These "alpha waves" have been used to diagnose various brain conditions, but for a long time no one understood their function. Now, said Dr. Hoagland, many neurologists believe that they are "scanning devices" like the electron beam that scans the image in a television transmission tube.

The subject sits with his eyes closed and thinks, for instance, about a familiar face. An alpha wave sweeps across his brain. In some mysterious way, not yet understood, the wave is able to select the right impulses stored in the memory circuits. Many impulses, representing color, shape, light and shade, blend together into a picture of the remembered person's face.

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