Measurements of maximum isometric tension and rate of onset of tension in fibers of glycerinated rat muscle indicate that the red soleus fibers develop significantly higher tensions than do white medial gastrocnemius fibers. Gastrocnemius fibers develop tension at a significantly faster rate than soleus fibers, however. These differences seem to be related to formation of actinmyosin cross-links.

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SUMMARY Sensory thresholds, using the 2-alternative forced choice technique, were studied in normal subjects and in patients with unilateral cerebraJ vascular disease, as documented by clinical-radiologlc correlation. In normal persons the absolute threshold for light touch increased with age. Bilateral impairment of sensation with unilateral cerebral vascular lesions occurred in 30% of the patients. Tactile deficit was always greater on the side contralateral to infarction or hemorrhage. An ipsilateral deficit did not exist independent of contralateral deficit, and was more likely to occur with complete sensory loss contralaterally. There was a tendency for persons with larger lesions as determined clinically and by CAT scan to have ipsilateral as well as contralateral deficit. The incidence or severity of ipsilateral deficit was not related to lesion laterally.

I n an earlier study, electrical activity in muscle was analyzed, using mathematical procedures and digital computer techniques to determine the effect of potential amplitude, wave shape, repetition rate and pulse duration on the harmonic spectrum (1). Special attention was directed toward the low frequency end of the spectrum because of the difficulty, in earlier studies, in extending the analysis in this direction. It was found that muscle potential amplitude and repetition rate could not be differentiated by size or shape of the spectrum. The principal characteristic of wave shape that could be detected was the base line duration of major amplitude muscle potential phase. Although previous studies had pointed in this direction (24), there were certain limitations in ease and rapidity of technique and in lower frequency limit of the analyzers, which led us to extend our studies, using procedures .which might be more suitable in the clinical situation than those we had used previously.In the previous study (l), the ulnar nerve was stimulated at the elbow, the muscle potentials obtained with a concentric needle electrode within the abductor digiti quinti muscle were photographed and the amplitudes of this potential were measured at 90 intervals. These amplitudes were then coded on IBM punch cards as input for a computer, and harmonic amplitudes of a Fourier series were calculated. This was a time consuming and costly procedure, though precise. The first goal of the present study was to determine whether analyses obtained by a commercially available wave analyzer were similar to those obtained with the procedure described above. If this were true, then studies would be extended to patients with proven myopathy or neuropathy. METHODSIn 10 subjects who had been studied previously (l), the frequency of the peak harmonic was calculated from data obtained with the digital computer. In 11 additional normal subjects, harmonic analyses were obtained utilizing a HewlettPackard wave analyzer (302A) with a flat frequency range from 20 cps to 50 kc.