This is new research from Northwestern Medicine, they provide strong evidence that the brain uses predictive coding to generate "predictive templates" of specific smells. The study was published in the journal Neuron, October 6.
Moments before you actually smell something it is likely that your brain is already preparing your sensory system for the familiar smell. This predictive coding is important because it allows animals (humans) to more quickly and accurately respond to stimuli in the surrounding environment. To support their claim the team used fMRI (functional Magnetic Resonance Imaging) and other techniques to identify the existence of predictive coding in the olfactory cortex of the brain.