Brain Rules - John Medina

Rating 8/10

My Summary:

The author takes a deep dive into what make our brains function well. The suggestions are delightfully straightforward: sleep more, stress less, eat better, exercise, and more. These lessons that we have heard from our parents many times are backed up with scientific evidence and quirky studies, leaving a feeling of ‘how could I not follow this advice’. I had no idea the adrenaline glands were down next to one’s kidneys.

Quotes:

In fact, the human brain cannot simultaneously activate more than 2 percent of its neurons at any one time. More than this, and the glucose supply becomes so quickly exhausted that you will faint.

Stated informally, we can make things up that aren’t there. We are human because we can fantasize.

Symbolic reasoning, this all-important human trait, takes almost three years of experience to become fully operational. We don’t appear to do much to distinguish ourselves from apes before we are out of the terrible twos.

This was the first real evidence that the prefrontal cortex governs several uniquely human cognitive talents, called “executive functions”: solving problems, maintaining attention, and inhibiting emotional impulses. In short, this region controls many of the behaviors that separate us from other animals. And from teenagers.

The solution? Give birth while the baby’s head is small enough to fit through the birth canal. The problem? You create childhood. The brain could conveniently finish its developmental programs outside the womb, but the trade-off was a creature vulnerable to predation for years and not reproductively fit for more than a decade.

The surgeon can’t predict the function of very precise areas in advance of the surgery because no two brains are wired identically.

The best you can say is that people who appear to be good at multitasking actually have good working memories, capable of paying attention to several inputs one at a time.

It’s a bit weird if you think about it. Making something more elaborate usually means making it more complicated, which should be more taxing to a memory system. But it’s a fact: More complexity means greater learning.

Even when I went to bed that night, the hippocampus was busy feeding signals about Austerlitz back to the cortex, replaying the memory over and over again while I slept. This offline processing provides an almost absurdly powerful reason to advocate for regular sleep.

The nap zone also is literally fatal: More traffic accidents occur during it than at any other time of the day.

Sleep loss hurts attention, executive function, immediate memory, working memory, mood, quantitative skills, logical reasoning ability, general math knowledge. Eventually, sleep loss affects manual dexterity, including fine motor control (except, perhaps, for pinball) and even gross motor movements, such as the ability to walk on a treadmill.

There is no unique grouping of physiological responses capable of telling a scientist whether or not you are experiencing stress. The reason? Many of the same mechanisms that cause you to shrink in horror from a predator are also used when you are having sex—or even while you are consuming your Thanksgiving dinner. To your body, saber-toothed tigers and orgasms and turkey gravy look remarkably similar. An aroused physiological state is characteristic of both stress and pleasure.

These hormones are secreted by the adrenal glands, which lie like a roof on top of your kidneys. The adrenal glands are so exquisitely responsive to neural signals, they appear to have once been a part of your brain that somehow fell off and landed in your mid-abdomen.

The current education system starts in first grade, typically around age 6. The curriculum is a little writing, a little reading, a little math. The teacher is often a complete stranger. And there is something important missing. The stability of the home is completely ignored, even though it is one of the greatest predictors of future success at school.

Individually, the worst kind of stress is the feeling that you have no control over the problem—you are helpless.

Author W. Somerset Maugham once said: “There are only three rules for writing a novel. Unfortunately, nobody knows what they are.”

One company tested the effects of smell on business and found a whopper of a result. Emitting the scent of chocolate from a vending machine, it found, drove chocolate sales up 60 percent. That’s quite a motivation. The same company installed a waffle-cone-smell emitter near a location-challenged ice cream shop (it was inside a large hotel and hard to find). Sales soared 50 percent, leading the inventor to coin the term “aroma billboard” to describe the technique.

We live in a three-dimensional world, but the light falls on our retina in a two-dimensional fashion. The brain must deal with this disparity if it is going to accurately portray the world.

Women tend to use both hemispheres when speaking and processing verbal information. Men primarily use one. Women tend to have thick cables connecting their two hemispheres. Men’s are thinner. It’s as though females have a backup system that is absent in males.

Men and women respond differently to acute stress: Women activate the left hemisphere’s amygdala and remember the emotional details. Men use the right amygdala and get the gist.

For little ones, discovery brings joy. Like an addictive drug, exploration creates the need for more discovery so that more joy can be experienced. It is a straight-up reward system that, if allowed to flourish, will continue into the school years. As children get older, they find that learning not only brings them joy, but it also brings them mastery. Expertise in specific subjects breeds the confidence to take intellectual risks. If these kids don’t end up in the emergency room, they may end up with a Nobel Prize.

Babies are the model of how we learn—not by passive reaction to the environment but by active testing through observation, hypothesis, experiment, and conclusion.