5 Things You Didn’t Know About the Brain

Image Edited from Flickr
  1. Exactly How Big and Complex is the Brain?
  2. Does Brain Size Matter?
  3. What Happens to the Brain as We Age?
  4. Can the Body Make New Brain Cells?
  5. How are Functions Represented in the Brain?

1. Exactly How Big and Complex is the Brain?

Here are some of the questions I had and some of the quick facts:

  • Weight of brain: ~3 pounds
  • Number of Cells in Brain: ~270B
  • Neurons in the brain: ~100B
  • Number of connections / synapses: ~100T
  • Average number of connections per neuron: ~1000
  • Largest node AI system: e.g. GPT-3 @ 185B (20% of brain)
  • Size of neuron: cell body (0.1mm), axon (nerve) can be 1.0m long
  • Number of neurotransmitter molecules working: Billions
  • Nerve speed: The fastest nerve cells carry messages at 120m/s (268mph)
  • Speed of pain: slow pain 2.0m/s, fast pain 20m/s (4.4–44mph)
  • Time to form a conscious thought: ~150ms
  • How much memory storage: Estimates range: ~2.5GB — 2.5Petabytes
  • Size of nervous system? Length of all nerves added up: 100,000 miles
  • Voltage of the Brain: 65mV
  • Energy used by the brain: 500 calories/day = 25% total calories/day
  • Time it would take to charge a smartphone with your brain: 70 hours
Interesting Brain Facts. Image Credit

2. Does Brain Size Matter?

Actually I assumed brain size didn’t matter so much (a sperm whale brain is 20 pounds!) but it seemed to me that having more neurons and corresponding brain complexity would be important. We add more neurons as we grow up => we get smarter, therefore more neurons => better and smarter.

3. What Happens to the Brain as We Age?

What happens to cognitive function during aging? And how to keep the mind “sharp” as we age? Scientists don’t appear to have concrete answers to these questions, but it has been widely found that brain volume shrinks about 5% per decade after the age 40 and much faster after the age of 70. It is thought, but not confirmed, that this decline is a function of neuron cell death. The hippocampus, essential in the formation and retrieval of memories, in particular deteriorates with age. Additional factors are that hormones that protect and repair brain cells decline with age, and decreased blood flow to the brain impairs memory and cognitive skills.

4. Can the Body Make New Brain Cells?

This appears to be a hotly debated topic. The classic belief was that brain cells generate and develop during youth and adolescence and then cease to generate during adulthood. In modern times (say the last 10-20 years), that historical dogma had been over-turned and the new thinking was that neurogenesis — the adult generation of new neurons / brain cells — does take place. This of course is very encouraging and means that there may be ways to stimulate adult generation of brain cells and perhaps counter age related brain decline and diseases like Alzheimers. But then, even more recent research has challenged that challenger research. I’d say its safe to say scientists don’t know — but its far from definitive and neuroplasticity and neurogenesis remain exciting and important research topics.

5. How are Functions Represented in the Brain?

Iwas curious to know if each part of our human functionality was equally represented in the brain — you know a section for hearing, a section for vision, a section for craving tacos, etc. The short answer is no. While certain functions can be substantially represented in one area, the brain often uses multiple areas in tandem to accomplish functionalities. One fascinating finding and result of evolution, is that the brain has evolved to accomplish certain number of functions and in some cases may re-use the existing hardware to accomplish some different and new goals. One example is the use of the “disgust” capability of the insula or insular cortex. Historically disgust evolved to detect bad food and for food safety (e.g. that smells disgusting!). However, overtime the same neuroanatomy has evolved to trigger and light up for the perception of disgust on moral grounds. That is why certain types of adverse or immoral behavior give us that same feeling of disgust and make us want to take a shower or wash our hands. e.g. “Come out, damned spot!” -Lady MacBeth

Conclusion

This wraps-up the brain series and my first attempt at learning more about the brain and neuroscience. If you haven’t read the earlier articles, please feel free to check them out here.

References:

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Zubair Talib

Zubair Talib

Loves Technology, Startups, and Tacos.