Meeting Abstract
P3.90 Jan. 6 Optimality of the array of mechanoreceptors on cricket cerci GEDEON, Tomas*; CUMMINS, Bree; CUMMINS, Graham; MULDER-ROSI, Sep; MILLER, John M.; JACOBS, Gwen; Montana State University; Montana State University; Montana State University; Montana State University; Montana State University; Montana State University gedeon@math.montana.edu
An implicit hypothesis underlying a great deal of recent research in neuroscience and neuroethology is that sensory systems have evolved, through natural selection, toward optimal functional performance and/or energetic efficiency. However, it has proven difficult to derive precise definitions for functional optimality and efficiency. We have developed and applied a theoretical and experimental framework for defining and assessing optimality in one sensory system: the cercal system of the cricket. The working hypothesis is that global anatomical, biomechanical and neurophysiological characteristics of the cerci are optimized for the sensory processing operations they mediate. We calculated the air-current-induced movement of individual hairs using Stokes equations, including terms which account for the fluid-dynamical interaction with nearby hairs, and characterized the amplitude and phase of hair movements as a function of the amplitude, frequency and direction of air current stimuli, the length of the hair, and the local density and characteristics of surrounding hairs. To set model parameters, we observed the motion of individual hairs in response to arbitrary air current stimuli. To determine the effect of hair-to-hair interactions, movements of some hairs were measured before and after the removal of surrounding hairs. We also characterized the distribution of mechanosensory hairs within specific regions on the cerci, as a basis for an evaluation of the extent to which that distribution might have become optimized for signal sensitivity. Hypotheses related to optimality were then tested by computing the effects of manipulating biomechanical model parameters on sensory performance parameters.
