Expectancy is a major function of the nervous system that prepares the organism to react in a meaningful way to the sensory flow depending on the recent internal and external contexts. While this anticipation ability has been mainly studied under passive conditions, here we aim at unravelling the neuronal mechanisms underlying expectancy coding in the context of an active tactile sensorimotor task in mice. In this purpose, we designed a new behavioral task in which mice are trained to contact several times a fixed object with a spared single whisker to obtain a reward. During sessions performed with expert animals, we randomly interleaved omission trials where the object is removed between two whisks. The sudden withdrawal of the object while mice are engaged in a process of touch-related perception therefore creates a deviance between expected and received tactile inputs. We developed a purpose-built system for the real time monitoring of single whisker contacts, at a rate that is compatible with the frequency range of the whisking process and with the extremely small forces produced by mono-whisker touches. Using this setup, we trained mice to generate sequences of four successive whisker contacts, at a sustained pace and in a reproducible manner. The random omission of the object in expert mice has revealed a rapid reorganization of their whisking motor strategy: while the first whisking cycles have an amplitude adapted to the usual object position, subsequent whisking cycles show a gradual increase in the protraction angle as mice sweep their whiskers beyond the field of the object. With the aim of revealing neuronal signatures of tactile expectations in the primary somatosensory cortex (S1), we have performed pilot acute electrophysiological multisite recordings in this area during sessions including omission trials in expert mice. The analysis will include a comparison of action potential discharges in layers 2-3 and 4-5 of S1 during standard trials, when the object is immobile, with the ones elicited during omission trials. We will specifically focus our attention on the neuronal activity at the expected moment of touch during omission trials, when error signals are likely to emerge from the deviance between expected and actual tactile sensory inputs.