The mechanisms underlying major aspects of the human brain remain a mystery. It is unknown how verbal episodic memory is formed and integrated with sensory episodic memory. There is no consensus on the function and nature of dreaming. Here we present a theory for governing neural activity in the human brain. The theory describes the mechanisms for building memory traces for entities and explains how verbal memory is integrated with sensory memory. We infer that a core function of dreaming is to move charged particles such as calcium ions from the hippocampus to association areas to primary areas. We link a high level of calcium ions concentrations to Alzheimer's disease. We present a more precise definition of consciousness. Our results are a step forward in understanding the function and health of the human brain and provide the public with ways to keep a healthy brain.