What percentage of your brain do you use? - Richard E. Cytowic

Summary

The 10% brain myth has persisted for over a century, despite being scientifically debunked. In reality, the human brain uses about 20% of the body’s energy, with most of it spent maintaining neural activity. The brain’s efficiency is optimized by 'sparse coding,' where only a small percentage of neurons are active at a time. This allows the brain to process information without wasting energy. Multitasking is inefficient because it exceeds the brain’s energy limits. Rather than needing to unlock untapped brain power, we should appreciate the brain’s incredible capacity to function efficiently with the resources it has.

Takeaways

• 😀 The '10% of the brain' myth is completely false; we use much more of our brain than commonly believed.
• 😀 William James, the father of American psychology, used the idea of not meeting mental potential as a challenge, not an indictment of brain usage.
• 😀 Frontal and parietal lobes, once considered 'silent areas,' are now understood to be crucial for executive functions like planning, reasoning, and adapting.
• 😀 The brain is an energy-intensive organ, consuming 20% of the body’s daily glucose despite representing only 2% of body mass.
• 😀 Human brains are densely packed with neurons, making us smarter than other species in proportion to our brain size.
• 😀 Cooking, invented 1.5 million years ago, helped early humans support a brain with 86 billion neurons by making food easier to digest and absorb.
• 😀 Half the energy the brain uses goes into maintaining its structure and electrical charge, with the remaining energy supporting cognitive tasks.
• 😀 The brain employs a method called 'sparse coding,' where only a small proportion of neurons fire at once to conserve energy and maximize information processing.
• 😀 About 1-16% of neurons are active at any given time, which is the energy-efficient limit for maintaining consciousness and brain function.
• 😀 Multitasking is inefficient because the brain lacks the energy to do multiple tasks at once effectively; focusing on one task at a time is far more productive.
• 😀 Guilt over not 'using' your brain fully is misplaced; your brain is already highly optimized for energy efficiency and cognitive performance.

Q & A

What is the origin of the myth that we only use 10% of our brain?

The myth originated in the 1890s when William James, the father of American psychology, said that most people do not meet their mental potential. This was meant as a challenge, but over time it became misunderstood as a claim that 90% of the brain was inactive, which is incorrect.

Why did scientists originally think certain areas of the brain, like the frontal and parietal lobes, were 'silent' or inactive?

Scientists once believed these areas were inactive because damage to them didn’t result in motor or sensory deficits. Without observable effects, they assumed these areas served no significant function.

What role do the frontal and parietal lobes play in brain function?

The frontal and parietal lobes are crucial for executive functions, including abstract reasoning, planning, decision-making, and adapting to new situations. They enable the complex cognitive abilities that define human intelligence.

How does the energy consumption of the human brain compare to other animals?

Despite being only 2% of the body’s mass, the human brain consumes 20% of the body's daily energy in the form of glucose. In comparison, rodent and canine brains use 5% of total body energy, and monkey brains use 10%.

Why do human brains consume so much energy relative to their size?

Human brains are particularly energy-intensive because they have a high concentration of neurons, requiring significant energy to maintain electrical charges across the cells and sustain complex neural functions. This energy is necessary to support advanced cognitive abilities.

How did cooking contribute to human brain evolution?

Cooking allowed our ancestors to consume food that was softer and easier to digest, making more energy available for the brain. This freed up time and resources that would otherwise be spent on digestion, enabling humans to support a larger and more complex brain.

What is the relationship between brain size and energy expenditure in humans and other species?

Humans have a high neuron density, meaning their brains are packed with more neurons than other species relative to brain size. This density requires a lot of energy to function, which is why humans have evolved a brain that consumes more energy than other species, even those with larger brains like elephants and whales.

What is sparse coding, and why is it important for brain efficiency?

Sparse coding is a method by which only a small percentage of neurons are active at any given time, allowing the brain to process large amounts of information with minimal energy. This strategy maximizes efficiency while minimizing the energy cost of neural activity.

Why is it impossible to multitask effectively, according to the script?

Multitasking is inefficient because the brain lacks the energy resources to perform multiple tasks at the same time effectively. Trying to do several things at once spreads energy too thin, leading to a decline in performance on each task.

What does the script suggest about the brain's efficiency in terms of energy use?

The brain has evolved to balance the need for cognitive processing with energy efficiency. Only 1% to 16% of neurons are typically active at any given time, optimizing energy consumption while still allowing for complex cognitive functions and conscious awareness.