The influence of various conditions on the time relations of tendon reflexes in the human subject

• Published in: Proceedings of the Royal Society of London. Series B, Containing papers of a biological character Containing papers of a biological character, 1922-09, Vol.94 (657), p.92-98
• Main Authors: Golla, Frederick, Hettwer, Joseph
• Format: Article
• Language: English
• Subjects: Flexors; Galvanometers; Mental stimulation; Muscles; Patellar ligament; Pendulums; Reflexes; Refractory periods; Stretch reflex; Synapses
• ISSN: 0950-1193; 2053-9185
• DOI: 10.1098/rspb.1922.0044

The following observations constitute a preliminary account of an investigation into the time relations of certain reflexes in the human subject. The knee-jerk was primarily selected for study. The variability of magnitude of the knee-jerk in response to equal stimuli has been commented on by the majority of observers, and, according to Seheven, such a variable response may occur even in the decerebrate animal. Whether variations of the irritability of the spinal reflex centre take place in the intact human subject there is no means of knowing, but study of the human responses has convinced us that by far the greatest factor in determining the variability of the knee-jerk is cortical activivity, and that, by taking suitable precautions, variability may be reduced to a negligible factor. In a previous publication, one of us (F. G.) has shown that these variations of the knee-jerk are secondary to alterations in the tonus of the quadriceps muscle. It was found that any stimulus of a nocuous nature, whether physical or psychical, caused an increase in the quadriceps tonus when the limb was flexed in the position in which the knee-jerk is elicitable, and that the magnitude of the knee-jerk was correspondingly increased. Similarly, pleasurable stimuli leading to an inhibition of effort were responded to by diminished quadriceps tonus and a diminished knee-jerk. It was found in our present experiments that, by using a trained subject and avoidance of all sources of psychical disturbance, it was possible to obtain responses to uniform stimuli which only rarely showed any irregularity. Neglect of the psychical factor has been the cause of the irregularity of response noted by so many observers. Uniformity of the stimulus was secured by the use of electrically released pendulums, which could be weighted to any desired extent. The relatively inefficient slow pushing stroke of the pendulum on the patellar tendon was converted into a more efficient stimulus of briefer duration by interposing a small piece of metal-covered wood, held in position by a stout springy steel rod. This anvil, for the reception and conversion of the pendulum blow, is adjusted in contact with the patellar tendon, and on the pendulum striking it the circuit of a Deprez signal is closed, and the moment of stimulation is photographed on the recording paper. The muscular response was recorded by photographing the excursions of the string of an Einthoven galvanometer, through which the muscle curre