Mechanical transmission in a Pacinian corpuscle. An analysis and a theory

• Published in: The Journal of physiology 1966-01, Vol.182 (2), p.346-378
• Main Authors: Loewenstein, W. R., Skalak, R.
• Format: Article
• Language: English
• Subjects: Biophysical Phenomena; Biophysics; Models, Theoretical; Nerve Endings - physiology; Pressure
• ISSN: 0022-3751; 1469-7793
• DOI: 10.1113/jphysiol.1966.sp007827

1. An analysis is made of the transmission of mechanical forces through the Pacinian corpuscle. In particular, forces are analysed which produce pressure differences at the centre of the corpuscle and lead to excitation of the sensory nerve ending. 2. The main structural elements in force transmission through the corpuscle are the lamellae, their interconnexions, and the interlamellar fluid. The two former provide the elastic elements and constraint for the fluid; and the latter, the viscous elements. The mechanical equivalent incorporating these elements is a system of dashpots (the lamellar surfaces and the interlamellar fluid) and springs (the lamellae and their interconnexions); it is a mechanical filter which suppresses low frequencies. The dynamic and static patterns of lamella displacements in the equivalent are in close agreement with those observed in Pacinian corpuscles. 3. Steady-state and transient pressure fields were determined for the equivalent. Under static compression, only elastic forces exist in the corpuscle. Analysis shows that such forces are transmitted poorly from periphery to centre through the lamellated structure. The compliance of the lamellar interconnexions is so high in relation to that of the lamellae themselves, that most of the pressure load is carried by the outer lamellae. As a result, only a small fraction of the steady-state pressure at the outer surface reaches the centre of the corpuscle where the sensory ending is located. This is the mechanical basis of receptor adaptation. 4. Under dynamic compression, viscous forces develop in the corpuscle; and these account for most of the pressure at times too early for development of elastic deformations. Analysis shows that such forces are transmitted well. For example, if a typical corpuscle of 500μ diameter is compressed by 20μ linearly during 2 msec, the pressure differences near to the centre of the corpuscle are initially as high as at the periphery, and stay within the same order throughout the process of compression. In general, pressure at the centre increases steeply with velocity of compression. This explains the marked velocity dependence of the generator response of the sensory ending. If, in the foregoing example, the 20μ compression is held fixed after 2 msec, the pressure differences at the centre fall abruptly to near zero with the onset of the static phase. The duration of pressure transients at the centre approximates that of the `active' phase of the g