Spectral composition of muscle spindle Ia responses to combined length and fusimotor inputs

It is well known that time and frequency domain analyses provide alternative methods for examining the properties of time series. It is less well known that interesting features of a data set may appear more clearly in one or another of these domains, although, theoretically, they contain the same information (Tukey, 1980). Time domain descriptions of spike trains are traditionally used by neurophysiologists, whereas frequency domain methods for examining the statistical properties of spike trains are not widely used. The purpose of the present report is to illustrate the useful -ness of spectral methods by pointing out an interesting feature of the muscle spindle Ia discharge in the presence of a simultaneously applied length and fusimotor input.