Scientists explore where consciousness arises in the brain

Consciousness is at the centre of human existence, the ability to see, hear, dream, imagine, feel pain or pleasure, dread, love and more.

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But where precisely does this reside in the brain? That is a question that has long confounded scientists and clinicians. A new study is offering fresh insight.

In a quest to identify the parts of the brain underpinning consciousness, neuroscientists measured electrical and magnetic activity as well as blood flow in the brains of 256 people in 12 laboratories across the United States, Europe and China, while the participants viewed various images. The measurements tracked activation in various parts of the brain.

The researchers found that consciousness may not arise in the “smart” part of the brain - the frontal areas where thinking is housed, which progressively grew in the process of human evolution - but rather in the sensory zones at the back of the brain that process sight and sound. “Why is any of this important?” asked neuroscientist Christof Koch of the Allen Institute in Seattle, one of the leaders of the study published this week in the journal Nature.

"If we want to understand the substrate of consciousness, who has it — adults, pre-linguistic children, a second trimester foetus, a dog, a mouse, a squid, a raven, a fly — we need to identify the underlying mechanisms in the brain, both for conceptual reasons as well as for clinical ones," Koch said.