Recording-2025-03-05T00:08:06.636Z

Neurons and Brain Capacity

• The human brain contains approximately 86 billion neurons.

  • This number was once believed to be 100 billion.

  • Interesting Comparison: The Milky Way galaxy is estimated to also have about 100 billion stars.

Size of the Milky Way

• The Milky Way is roughly 100,000 light years across.

• Estimates of celestial bodies can be similar to estimates in brain cell counts, highlighting the vastness of both.

Neurons vs Connections

• Brain capacity isn't solely determined by the number of neurons.

  • Connections and density of the neurons play a significant role in brain function.

• An elephant possesses around 257 billion neurons, but is not considered smarter than humans despite having more neurons.

Glial Cells

• The human brain has approximately 86 billion glial cells.

• Types of Brain Cells:

  • Neurons

  • Glia

• Previous assumptions suggested a ratio of 10 glia cells for every neuron, but research from Susana Herculano-Kruse indicates that is not the case.

Synapses and Connections

• Total neuronal connections: estimated at 100 trillion.

• Each neuron can form between 7,000 to 15,000 connections to other neurons.

  • Variability exists based on brain region.

• In 1 mm³ of brain tissue, there can be:

  • 50,000 neurons

  • Up to 1 million synapses.

Speed of Neuronal Signals

• Signal transmission speed can reach up to 220 mph, with some sources claiming up to 270 mph.

• The brain can perform calculations at a staggering rate of up to 10^16 calculations per second.

Energy Consumption

• The brain uses around 50 calories a day.

• Major energy consumers include sodium-potassium pumps, which account for about 40% of the brain's energy expenditure.

  • These pumps help reestablish the resting potential of neurons.

Memory Storage Capacity

• Rough estimate for brain storage capacity: approximately 2.5 million gigabytes.

• This translates to enough storage for around 3 million hours of TV shows.

  • Some researchers believe the actual storage capacity may be higher, but estimating is complicated.