This research aims to increase our understanding of sensory transduction in somatic mechanoreceptors. Such receptors subserve a wide variety of sensory systems which convert mechanical forces to neural signals which are transmitted to the central nervous system. Very little information is available on the fundamental steps of the transduction process. We propose a study on the primary ending of the isolated mammalian muscle spindle which is an especially favorable preparation for a direct approach on the problem because of: the ability to study it in isolation, the relatively large size of the myelinated branches and their terminals, the accessibility of structures in our isolated decapsulated preparation and the ability to visualize its structure microscopically. Using newly developed techniques of imaging and patch clamping, we will investigate: 1) the conductance changes which occur in the nerve terminals in response to mechanical stress and the characteristics of stretch-activated channels. 2) the spread of potentials produced by the conductance changes along the myelinated branches of the ending and the site of impulse initiation, and 3) a quantitative study of the structure of the primary ending both its myelinated branches and unmyelinated terminals, which will allow us to derive an electrical model of the ending. This is essential for the interpretation of an understanding of the overall transduction process in the ending. Knowledge of the basic mechanisms of transduction may be very important for the understanding of many disorders affecting sensory systems.
