THE ELECTROPHYSIOLOGY OF THE NERVOUS SYSTEM
Readers of newspapers and magazines are becoming somewhat used to the periodic appearance of articles headlined "Recently perfected device records man's thoughts electrically." Such reports leave one with the impression that the precise neural correlates of "thought" have been discovered, that means to record them have been devised, and that in order to find out what a person is thinking a skilled technician need only start his apparatus and analyze the resulting graphic records of "brain waves."
But psychology and neurology have not advanced quite so far as such articles suggest. Our knowledge of the modes of action of the nervous system is still very far from being complete. Just how the brain functions in thinking remains largely unknown. And although it is possible to record "brain waves," as the experiments reported in this chapter show, the "waves" that have been recorded most successfully do not seem likely to have a direct relation to thought processes.
Yet if the investigations of "brain waves" have not yielded the dramatic results claimed for them by some popular science writers, they already have added considerably to our understanding of a number of psychological phenomena and they offer hope of illuminating the still mysterious relationship between neural activity and overt behavior. The present chapter deals with a few recent studies which have been selected to indicate the number and variety of psychological problems which controlled observations of these neuroelectrical waves may help to solve.
One of the basic discoveries in the field of neurophysiology was Helmholtz's proof that nerve impulses travel at measurable speeds, far below the speed of electromagnetic impulses. Less than one hundred years ago Johannes Müller, the most eminent physiologist of his day, taught that the velocity of conduction of she neural impulse could never