Teaching With the Brain in Mind

Teaching with the Brain in Mind
Cortex
FIGURE 2.3
Medial View of the Brain
Hypothalamus
Amygdala
Hippocampus
clusion that essential long-term memory traces for
motor learning are located in the cerebellum
(Thompson 1993).
Energy for Learning
Corpus Callosum
Thalamus
Cerebellum
Brain Stem
The brain is energy inefficient. It is about 2 percent
of the body’s adult weight, but it consumes about
20 percent of the body’s energy. How does the brain
get its energy to learn? Its primary source is blood,
which supplies nutrients like glucose, protein, trace
elements, and oxygen. The brain gets about 8 gallons
of blood each hour, about 198 gallons per day.
In addition, water provides the electrolytic balance
for proper functioning. The brain needs 8 to 12
glasses of water a day for optimal functioning.
Dehydration is a common problem in school classrooms,
leading to lethargy and impaired learning
(Hannaford 1995). The role of nutrition will be
10
explored in the next chapter, but for the moment
we can say that good diets do help learning.
Oxygen is, of course, critical to the brain. The
brain uses one fifth of the body’s oxygen. If the
blood supply to the brain is interrupted, we lose
consciousness in seconds. Fortunately, the brain
usually gets enough oxygen for basic functioning
because the carotid artery ensures the brain gets
freshly oxygenated blood first after leaving the
heart-lung area. Higher levels of attention, mental
functioning, and healing are linked to better quality
air (less carbon dioxide, more oxygen). Many of the
so-called “smart drugs” that boost alertness, cognitive
functioning, and memory enhance oxygen flow
to the brain. With only 36 percent of K-12 students
in a daily physical education class, are they getting
enough of the oxygen-rich blood needed for highest
performance? Many worry that they are not.
Where Learning Begins
There are two kinds of brain cells: neurons and glia.
While the majority of brain cells (90 percent) are
glia, it is the remaining 10 percent—the neurons—
are much better understood. The most studied brain
cells are neurons (Greek for “bowstring”). For the
sake of comparison, a fruit fly has 100,000 neurons,
a mouse has 5 million, and a monkey has 10 billion.
You have about 100 billion neurons. A single
cubic millimeter (1/16,000th of an inch) of brain
tissue has more than 1 million neurons. They are
about 50 microns in diameter. You lose your brain
cells every day through attrition, decay, and disuse.
Scientists differ on exactly how many; estimates vary
from 10,000 to 100,000 per day (Howard 1994).
You’ve got enough for your lifetime, though. Even if
you lost a half million neurons per day, it would
take centuries to, literally, lose your mind.