continuing my review of Brain Rules
The third rule of John Medina's book is fairly straightforward. Each of our brains is uniquely wired. He spends a bit of time going into the actual physical structure of the brain. A neuron (brain cell) is like a fried egg (53). The white is like cytoplasm, the yolk like the nucleus. If you smashed the egg with your foot, the points of the resultant star would be like dendrites. Stretch out one of the points of that star and squish the end and you have an axon with an axon terminal (53-54).
This is a nerve cell, a neuron. The space between them, the synaptic cleft, is swimming with molecules (neurotransmitters) that float back and forth between neurons (55). Each of these is part of a dense forest of branches. "When we arrive at the hippocampal neuron, it looks as if we've landed in an ancient, underwater forest... Everywhere there are submerged jumbles of branches, limbs, and large, trunk-like objects. And everywhere sparks of electric current run up and down those trunks" (54).
Where is he going with this description? "These branches appear to be moving" (56). We are observing the brain learning. "As neurons learn, they swell, sway, and split" (57). "The brain is constantly rewiring itself." And the more activity you do, the more complex your brain becomes (58). For example, the brains of wild animals are 15-30% larger than the brains of their domesticated equivalents.
The human brain grows in neuron density at different points of life. Babies start with about the same number of connections as adults (58-59). Then at 3 years old, the number of connections has doubled or even tripled at some points. Then they reduce to about the same as adult again until puberty. Then once again, the number of connections spikes.
These connections are unique to every individual. Even identical twins will wire up differently, even just because they are sitting at a different place on the couch watching TV (61-62). In a fascinating example, Medina tells how one brain surgeon who works with epilepsy has to spend hours at the beginning of surgery "mapping" the brain of the person he's operating on (64-65). Each brain is wired differently, so he has to spend some time probing the patient's brain to find what he needs to cut out.
Medina talks about how a person will have a specific neuron that fires when they look at a picture of Jennifer Aniston 60-61). (On a side note, it may more likely be a specific circuit of neurons that remember Jennifer Aniston rather than a single neuron). The point is that our memory consists of "experience dependent" wiring that we create as we go through and experience life (60). This is in contrast to "experience independent" wiring and "experience expectant" wiring that is set up for things like vision and language acquisition.
Here is the fundamental principle: "Learning results in physical changes in the brain, and these changes are unique to each individual" (62). Our brains are like the United States road network. "We have the neural equivalents of large interstate freeways, turnpikes, and state highways. These big trunks are the same from one person to the next" (63). These parts are predictable from person to person. "It's when you get to the smaller routes--the brain's equivalent of residential streets, one-laners and dirt roads--that the individual patterns begin to show up."
Howard Gardner is a leader of the Multiple Intelligences movement (63). His sense of the diversity of the brain has led him to suggest seven categories of intelligence: "verbal/linguistic, musical/rhythmic, logical/mathematical, spatial, bodily/kinesthetic, interpersonal, and intrapersonal" (64). Excellence in one area doesn't assure excellence in another. Indeed, the chapter begins by contrasting how well Michael Jordan, the famous basketball player, was at basketball with how poorly he did at baseball. His brain was wired to be genius at the one and average at the other.
The take-away of the chapter is that the current set up of education, which expects certain goals at a certain age, does not sufficiently take the uniqueness of individuals into account (67). "For example, about 10 percent of students do not have brains sufficiently wired to read at the age at which we expect them to read." The solution? The first is smaller class size.
"Given that every brain is wired differently, being able to read a student's mind is a powerful tool in the hands of a teacher" (67). Medina believes that the best teachers and communicators are inevitably those who have "advanced Theory of Mind skills," by which he means those who have skills at being able to read other people's minds, as in chapter 2 over survival. "An advanced skill set in Theory of Mind predicts a good teacher" (68). But a
teacher is going to have more difficulty getting to know the unique make-up of specific
individuals if the classes are too large.
Secondly, instruction should be customized to the individual student (68). This follows naturally from the fact that each person's brain is uniquely wired. Again,
it will be virtually impossible to do anything along these lines if classes are
too large. Increasingly, computer
software can help. Medina suggests that a combination of empathetic teachers with adaptive software that fills in the gaps in an individual's competencies might be optimal for learning. Ultimately, we might "dismantle altogether grade structures based on age" (69).