Sensory experience during perinatal life and adulthood modifies physiological and anatomical characteristics of the central nervous system. So far, this phenomenon has been studied in situations of complete or partial sensory deprivation. We here report that increased sensory stimulation, during four days, of a number of whisker follicles on the face of the adult mouse results in an increased immunoreactivity of glutamic acid decarboxylase (the biosynthetic enzyme of the inhibitory neurotransmitter GABA) in the somatosensory cortex of the adult mouse. Effects were limited to a column of tissue corresponding to the representation of the stimulated follicles and lasted two days beyond stimulation. These findings suggest that sensory stimulation transiently modifies local cortical processing.