How brain processes translate to consciousness is one of the greatest un­­-­solved questions in science. Although the scientific method can delineate events immediately after the big bang and uncover the biochemical nuts and bolts of the brain, it has utterly failed to satisfactorily explain how subjective experience is created.

As neuroscientists, both of us have made it our life’s goal to try to solve this puzzle. We share many common views, including the important acknowledgment that there is not a single problem of consciousness. Rather, numerous phenomena must be explained—in particular, self-consciousness (the ability to examine one’s own desires and thoughts), the content of con­sciousness (what you are actually conscious of at any moment), and how brain processes relate to consciousness and to nonconsciousness.

   
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ABOUT THE AUTHOR(S)
Christof Koch is professor of cognitive and behavioral biology at the California Institute of Technology, where he teaches and has conducted research on the neuronal basis of visual attention and consciousness for more than two decades. He is an avid hiker and rock climber who has scaled several noted peaks.

HIS THEORY: For each conscious experience, a unique set of neurons in particular brain regions fires in a specific manner.

Susan Greenfield is professor of pharmacology at the University of Oxford, director of the Royal Institution of Great Britain and member of the British Parliaments House of Lords. Her research focuses on novel brain mechanisms, including those underlying neurodegenerative diseases. Her favorite pastimes are squash and dancing.

HER THEORY: For each conscious experience, neurons across the brain synchronize into coordinated assemblies, then disband.