Adaptation and efficient coding

Abstract In this chapter we discuss adaptation and efficient representation. Adaptation is an essential feature of the neural systems of all species, a change in the input–output relation of the system that is driven by the stimuli and that is intimately linked with the concept of efficient representation. Through adaptation the sensitivity of the visual system is constantly adjusted taking into account multiple aspects of the input stimulus, matching the gain to the local image statistics through processes that aren't fully understood and contribute to make human vision so hard to emulate with devices. Adaptation happens at all stages of the visual system, from the retina to the cortex, with its effects cascading downstream; it's a key strategy that allows the visual system to deal with the enormous dynamic range of the world around us while the dynamic range of neurons is really limited.