Active sensing capabilities of the rat whisker system

The rat whisker system may be a good model for approaching the design of robust robotic active sensing and exploratory systems. Here we examine how rats use their whiskers (vibrissae) during free exploratory behavior and during a texture discrimination task. Results show that during free exploration, the rat rhythmically moves its head to place its small (micro) vibrissae on the surfaces it is exploring. These periodic "microvibrissal placements" are temporally synchronized with the whisking movements of the large (macro) vibrissae. The periodic microvibrissal placements occurred even during a texture discrimination task, in which a smooth, continuous movement might have been equally effective at extracting the required information. Finally, it was found that rats may sometimes use their micro and macro vibrissae consecutively, instead of simultaneously. This suggests that, like humans, rats' exploration consists of a series of movement sequences in which increasingly refined information is gathered about an object. Some implications of these results for the design of artificial exploratory systems are discussed.