A brain visual working memory circuit holds information in mind about what has just been seen. It represents the memory and distinguishes among objects via unique patterns of brain wave synchronization between neurons in the circuit. The large area of red in the lowest graph indicates that the brain waves in the two regions were highly in-sync after seeing a particular object - indicating that they were highly involved in holding in short-term memory information about that object. The modest amount of red for the top graph indicates lesser involvement for another object. By contrast, lack of red in the middle graph shows that the two groups of neurons weren't much involved in remembering a third object. So the memory of any particular object appears to be represented by its own unique mix of neurons oscillating in-sync.