Because the barrel cortex has a well-organised structure that relates clearly to the whisker pad, it has been used extensively as a tool to study sensory processing and development, and the phenomenon of experience-dependent plasticity - changes in the activity, connectivity, and structure of neural circuits in response to experience. Neurons in the barrel cortex exhibit the property of synaptic plasticity that allows them to alter the vibrissae to which they respond depending on the rodent's history of tactile experience. Experience-dependent plasticity is commonly studied in the barrel cortex by partially depriving it of sensory input, either by lesioning elements of the afferent pathway (e.g. the trigeminal nerve) or by ablating, plucking, or trimming some of the facial whiskers. The anatomical structure of the barrels is only affected by lesioning elements of the pathway, but innocuous forms of deprivation can induce rapid changes in the cortical map into adulthood, without any corresponding changes in the barrel structures. Because of their different effects, it seems these two paradigms work by different mechanisms.