Book Summary: Brain Rules

Book: Brain Rules

Author: John Medina

Key takeaways: See below-

Exercise: Exercise provides body access to food and blood. When you exercise, you increase blood flow across tissues. As the flow improves, body makes new blood vessels, which penetrate deeper and deeper into the body. This helps all functions, including brain function.

Wiring: Everyone’s brain is wired differently (you know this if you heard that story by Richard Feynman describing how his friend counted number by imagining a reel going in front of him vs. Feynman counting it touching his fingers). When babies are born, their brains have the same # of connections as adults. At the age of 2-3 these connections double/triple and by the age of roughly 8 are sheared back to the # that adults have. And then again, at puberty, it starts again, and by the time they’re ready to go to college, it settles back again. So, brain development has a double-humped shape.

Attention: During an emotionally charged event, amygdala releases dopamine, which helps memory and information processing. This is why we remember emotionally charged events vividly, and the brain remembers the emotional component of the memory the best (Maya Angelou was right when she said “People will forget what you said; people will forget what you did; but, people will never forget how you made them feel.”)

Short-term Memory: Here are some thoughts on how to remember ideas better –

  • The more elaborately we encode information at the moment of learnings, the stronger the memory: This is meaningfully related to the “Attention” section above. This is also somewhat related to Charlie Munger’s latticework framework, which says that things mean much more if your put them in a framework as opposed to understanding them individually. Finally, this is very important to the loci/memory palace method of remembering items.
  • A memory trace appears to be stored in the same parts of the brain that perceived and processed the initial input (not very useful to know, except it re-inforces the previous point).
  • Retrieval can be improved by recreating the environment at the time of creating the memory (again, not too useful for most of us).
  • Ideas are best remembered when real-life examples are given to substantiate the idea (very important and useful).

Long-term Memory: There are two models of long-term memory retrieval–library mode (where the brain knows where the memory is, so to say, and goes and gets it–this can work for hours to weeks) and detective mode (where brain goes in like a detective, gets a number of little clues and tries to piece a coherent story together, FILLING IN IMAGINED PARTS to make the story complete–this happens if we’re trying to remember the story after a long time). Here’s another shocking thing about the detective mode–it reconstructs the story anew with the new filled-in-parts and this becomes the new memory.

Long-term memory if formed with help from brain’s cortex (a wafer-thin layer of nerves blanketing the brain) and hippocampus (which plays a central part). Neurons leap from the cortex and snake their way to the hippocampus, which listens in and sends wires back into to the cortex. This back and forth helps form long-term memories. Here’s the amazing part–long after the initial stimuli has disappeared the cortex and hippocampus keep chatting, and after an extended period of time (when hippocampus is sure that the memory has been fully consolidated in the cortex), hippocampus lets go of the memory. How long can this process take? YEARS.

Sleep: is very important, and biological need for an afternoon nap is universal.

Stress: is no good. Our stress responses were shaped to solve problems that lasted for a short interval, not for years. They were primarily designed to get our muscles moving as quickly as possible, out of harm’s way. Under chronic stress, adrenaline causes blood vessels to scar (causing stroke/heart attack) and cortisol damages hippocampus (crippling the ability to learn/remember).

Sensory Integration: Every other sensory system must send a signal up to thalamus to get permission to contact the brain–EXCEPT smell.

Vision: “I will believe it when I see it”. Not so fast. It’s not that light strikes the retina and all that information is send to the back-office in the brain for processing to make sense of it all, and reflecting what’s out there. Instead, retina appears to begin processing information before it sends anything off to the Mission Control, packs information in “small movies” and send these movie to the back of our heads. Both of our eyes have a blind spot each. So how do we see what’s in these spots? As you can guess, our brains play a trick on us–based on 3D analysis of the areas around these blind spots the brain calculates what most likely is there and FILLS IN THE GAPS!! What does the brain fills in these gaps with–prior experiences of the person! The brain is forced to do this because it’s a 3D world and retina is two-dimensional.

Vision takes up roughly 50% of brain’s capacity (so we best close eyes as we are thinking hard).


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