B. W. Pietras
S. J. Bolanowski
Dept. of Bioeng. and Neurosci., Inst. for Sensory Res., Syracuse Univ., Syracuse, NY 13244
The Pacinian corpuscle is a tactile mechanoreceptor composed of a neural element surrounded by a multilayered, fluid-filled accessory capsule. Receptor potentials recorded from isolated Pacinian corpuscles in response to sinusoidal vibrations have nonlinear, asymmetric full-wave rectified transfer functions. The frequency response is U-shaped with a best frequency near 300 Hz. The Pacinian corpuscle's accessory capsule was studied experimentally and modeled theoretically to determine its mechanical contribution to the observed physiological response. Measurements of reactive force in response to sinusoidal compression showed that the reactive force is linear, and increases with frequency and amplitude. The compressive force can be described by a first-order linear differential equation of the form f(x,t)=kx+cdx/dt. Interlamellar fluid velocities and lamellar displacements were also computed for a range of frequencies. Computational simulations of the interlamellar fluid flow in response to sinusoidal displacement of the surface of the capsule shows that the multilayered structure linearizes the interlamellar fluid velocity, thereby linearizing the interlamellar compressive force. Thus both the mechanical filtering by the accessory capsule and the electrodynamical properties of the neurite contribute to the nonlinear, physiological response profiles seen in the receptor potential. [Work supported by NSF, IBN-9211561.]