MOST NEUROPHYSIOLOGICAL EXPERIMENTS deal with phenomena which last
for only a brief period of time, usually measured in milliseconds or seconds.
Commonplace subjective experience, however, indicates that longer lasting
effects may follow prolonged periods of sensory stimulation, Sensations of
motion, for example, may last for hours or days following a rough sea voyage
(for a vivid description of this effect see ref. 17). The French refer to
this as ma1 de debarquement. Analogously persisting aftereffects are observed
in the visual system (e.g., the “waterfall effect”) and auditory and
somesthetic systems. We presume that neurophysiological events must
underlie these illusions.
The present experiments were designed to record electrical activity taking
place along the auditory pathway before, during, and after prolonged
sound stimulation, in order to observe whatever neurophysiological aft,ereffects
may follow long-lasting stimulation. In addition to aftereffects, we
found other phenomena which merit analysis in their own right.