Constituents, organization and processes of the human brain

The human brain is an extraordinarily complex biological system underpinning cognition and experience. This complexity is evident at all levels, from genetics to molecular, cellular, network and systems constituents. This article provides an overview of these constituents, their organization and the processes in which they are engaged. We discuss the shaping influences of development and evolution, and describe the brain’s structure and function at several levels: cellular features, the organization of neurons into functional systems, the gross anatomy of the nervous system and the specific structural and functional properties of the cerebral cortex. There is considerable evidence that cortical activity – though not all cortical activity – is correlated with conscious experiences, but exactly which activities constitute consciousness is unclear.