Some High Tremor Frequencies

Abstract

Hill 1 demonstrated that in addition to the usual tremor frequency of 8 to 12 tremors per second, a tremor frequency of around 50 tremors per second could be recorded. He found that the tremors of higher frequency and lesser excursion were superimposed upon those of lower frequency and greater excursion. Travis and Hunter 2 called attention to the striking similarity between records of tremors and those of action currents and later recorded tremors of a rate as high as 200 per second. 3 The present paper reports the recording of tremors of a rate as high as 500 per second.

For the recording of the tremors we used an electrical current generator to activate, with or without the aid of amplification, a super-sensitive element of a Westinghouse oscillograph. All tremors were recorded from the extended forefinger of the firmly supported hand. Several healthy individuals served as subjects. By means of an electrical filter and amplifying system we were able to by-pass and amplify greatly only tremors of frequencies above 130 per second. When such recordings are compared with those obtained without the use of filter and amplifier some interesting relationships are revealed (Fig. 1). It is to be noted that each large tremor (in upper record) enduring approximately 0.1 sec. is really composed of a group of several oscillations (in lower record) occurring at a rate of about 200 per second. Further the tremor line between the volleys is not quiet. It presents both smaller oscillations of the same frequency as the larger waves in the volleys, and other generally still smaller oscillations of a frequency as high as 500 per second.