OUR THREE BRAINS
Paul MacLean says that we have
three brains.
MacLean called the first, most
primitive, brain the reptilian brain.
It is focused on individual survival and knows neither friend nor family nor
fun. In humans this consists of the brain
stem, which maintains the vital functions of life, including heartbeat,
breathing, metabolic activity, and the cerebellum. Even when extensive brain
injury occurs, if these areas are preserved, life can continue. The behaviors of this part of the brain are
very resistant of change, tend to be grounded in fear, and are not capable of
learning. This part of the brain is quite limited in its response to
challenges. - Reptiles (or human operating in the reptilian mode), when
perceiving threat, only attack, flee or freeze.
MacLean called the second brain the mammalian brain. It includes the
amygdala, a more refined sentry for danger than exists in the reptilian brain.
The amygdala joins with the hypothalamus, the pituitary and the adrenal glands
to coordinate our most basic fight-flight-freeze responses to protect us from
harm. The amygdala is activated automatically, without thought. For example, you walk out your front door,
and you see a shape on the grass that looks like a snake. You immediately jump back
with fear. Then you look more closely
and you see the shape is actually a garden hose. You relax, laugh, and go on
your way. The initial reaction was the
instinct of the early mammalian brain, including the amygdala. If that’s all you had, you might have
attacked or run away from the garden hose.
Our more evolved mammalian brain has
a more sophisticated sentry, the hippocampus, capable of refined perceptions
and feelings. It was the hippocampus
that helped you realize the garden hose was not a snake. The hippocampus has the capacity for learning
and memory, which gives mammals additional abilities. Unlike a reptile, your pet dog recognizes and
responds to you, and obviously makes the distinction between you and a
stranger.
The third, highest, component is
the human brain, which includes the
large cerebral cortex, making up five-sixths of the brain. This is our thinking brain, with numerous
connections between the hippocampus and the prefrontal cortex. The prefrontal cortex connects many large neural
networks that allow for the various qualities of human thought, reflection, and
wisdom.
The cerebral cortex is involved
with most advanced mental activities including speech, rational thought,
memory, understanding fine motor control, creativity, musical ability, writing,
empathy, kindness, the ability to be part of a family or group and still be an
individual, awareness of the story of your own life, and the recognition of
time.
Most of the stress we experience
cannot be handled well by the primitive
brain, with its fight-flight-freeze
reactions, or by the ancient or more advanced mammalian brains, with their limited capacities governed by
instinct, group conformance, and pecking
order.
Only by
accessing our human brain can we step back, reflect, and take conscious action.
Taken
from The Inner Game of Stress, W. Timothy Gallwey, pages 50-53.
