Why can olfactory learning increase the synchrony of neurons even when smells do not change over time?

In the context of perceptual learning, the increase in neuronal synchrony during olfactory learning—even when smells do not change over time—indicates that perceptual systems utilize temporal coding strategies that are not restricted to stimuli that vary temporally.1

While some forms of learning involve changes in the size of neural representations or the sharpening of neuronal tuning functions, other processes rely on modifying the relative timing of responses across a set of neurons. By increasing the synchronicity of firing across the ensemble of neurons that respond to a specific smell, the brain can effectively represent learned information through a temporal code, demonstrating that such strategies are a fundamental mechanism for processing sensory input regardless of whether the stimulus itself changes over time.1