Microvibrissae-based texture discrimination.

Rodents use their whiskers to detect a variety of tactile features of their environment. They do so by using two functionally distinct whisker systems: the macrovibrissae and microvibrissae. To determine the functional role of unexplored microvibrissae, we recorded from the cortical area representing the frontobuccal pad in anesthetized rats while presenting moving textures of varying coarseness. We find that surface coarseness is coded by the discharge rates of frontobuccal pad cortical neurons. Cortical neurons can use this response measure to robustly and reliably discriminate between the different textures. While neuronal discharge rates carry tactile information, the highly reproducible firing patterns of these neurons suggest that a single spike train may contain sufficient information to encode the stimulus. Together, these results indicate that rodents may use their microvibrissae to distinguish between surfaces having subtly different textures and shapes.