How is tactile information affected by parameters of the population such as non-uniform fiber sensitivity, innervation geometry and response variability?

Analysis of population responses in the tactile system requires a step beyond the isomorphic representations that are commonly presented. Using a simple model based on our data for spheres contacting the fingerpad, we illustrate how the parameters of the population itself have a profound effect on the fidelity of neural representations or codes. The effects of these parameters, such as innervation density, variability of sensitivity, type and covariance of noise are not apparent from single unit responses and, at least at present, require a theoretical or modeling approach of some sort. (C) 2002 Elsevier Science B.V. All rights reserved.