While lacking a coherent framework, scientists are making progress in mapping the correlations between brain activity and behavior.

New imaging tools reveal circuits and overall patterns of activity as people solve problems or reflect on their feelings. Genes expressed in mouse brain cells are being mapped so that researchers can begin to find out if neurons that look alike have different proteins and functions. A magnetic device can knock out human brain regions, safely and temporarily, to learn what those regions do.

In seeking an explanation for consciousness, a new mystery has emerged. Many scientists now believe that the brain basically works by simulating reality. The sights, sounds and touches that flow into the brain are put in the framework of what the brain expects on the basis of previous experience and memory.