Edward Tamler

Activity of a human oculorotary muscle unit

Abstract Single unit responses were recorded, even during strong contraction, by means of a concentric electrode with a 10–25 μ diameter core. During progressively increasing contraction which lasted 8 sec, a single unit was followed and its amplitude and frequency (or period) plotted. Two patterns of activity are distinguished. A tonic activity is seen, starting at fewer than 10/sec, increasing in frequency as the muscle contracts to more than 100/sec. Superimposed on this tonic response the same unit exhibits brief bursts of one to four spikes, as high as 270/sec, which may occur as often as at half second intervals. In another subject, a unit reached the frequency of 350/sec. These bursts of activity can be interpreted as either a response to irritation by the electrode or as genuine phasic activity. The theoretical significance of the pattern interpretation is discussed.