Although it is commonly believed that brain cell growth stops after age 20, that is not completely true. New connecting cells, called dendrites, can be formed throughout life. It is true that the neurons where memory storage takes place are not replenished; however, their extensions, these dendrites, continue to sprout and connect to form new circuits with other dendrites throughout life. These neural networks, similar to electric circuitry, are the roadways that connect various parts of the brain.
After repeated practice, working memories are set down as neuronal circuits of axons and dendrites ready to be activated when the information is needed. When a memory has been recalled often, its neuronal circuitry are highly developed because of their repeated activation.
The brain is divided into lobes, each with many functions, each interconnecting to the other lobes through nerve pathways and circuits. For example, areas in the left frontal lobe and both temporal lobes are integral in executive attention - alerting the rest of the brain to pay attention or respond to stimuli.