Jansen J K, Rudjord T
Science. 1965 Sep 3;149(3688):1109-11. doi: 10.1126/science.149.3688.1109.
The response to muscle stretch of second-order neurons of the dorsal spinocerebellar tract was studied in anesthetized cats. Three different types of neurons are defined; the response of each type is remarkably similar to that of the corresponding stretch-receptors of the muscle. Accordingly, the cerebellum receives information on the mechanical situation in muscle from three qualitatively different channels: one has a high degree of sensitivity to dynamic stretch (Ia units) and provides a mixed signal of muscle length and speed of movement; another provides information mainly on muscle length (group-Il units); and the third signals information on the degree of contraction of the muscle (Ib units).
