Figure 2: A schematic depiction of the relationship between sensory codes and memory codes in relation to auditory physiology and learning/memory. At the psychological level events become percepts, some of which become memories. At the neural systems level, sensory stimuli (sounds) are processed at various levels of the auditory system, some of which become engrams (the neural bases of memories). At the neuronal level, sounds evoke discharges in cells, some of which reflect plasticity underlying engrams, e.g., by changing synaptic strength. Coding consists of algorithms that transform an input into a neural representation. For example, sensory codes can represent different sound frequencies as spectral receptive fields. Memory codes represent a cardinal feature of memory, in this case, the strength of a memory, as shown by representing the behavioral importance of a sound as an increasing amount of tuning change.