THE BRAIN FROM BOTTOM TO TOP
The most important job of the brain is to ensure our survival, even under the
most miserable conditions.
Everything else is secondary. In order to do that,
brains need to:
(1) generate internal signals that register what our bodies
need, such as food, rest, protection, sex, and shelter;
(2) create a map of the
world to point us where to go to satisfy those needs;
(3) generate the neces-
sary energy and actions to get us there;
(4) warn us of dangers and opportuni-
ties along the way; and
(5) adjust our actions based on the requirements of
And since we human beings are mammals, creatures that can
only survive and thrive in groups, all of these imperatives require coordination and collaboration.
Psychological problems occur when our internal
signals don’t work, when our maps don’t lead us where we need to go, when
we are too paralyzed to move, when our actions do not correspond to our
needs, or when our relationships break down.
Every brain structure that I
discuss has a role to play in these essential functions, and as we will see,
trauma can interfere with every one of them.
Our rational, cognitive brain is actually the youngest part of the brain
and occupies only about 30 percent of the area inside our skull.
brain is primarily concerned with the world outside us: understanding how
things and people work and figuring out how to accomplish our goals, man-
age our time, and sequence our actions.
Beneath the rational brain lie two
evolutionarily older, and to some degree separate, brains, which are in charge
of everything else
: the moment-by-moment registration and management of
our body’s physiology and the identification of comfort, safety, threat, hun-
ger, fatigue, desire, longing, excitement, pleasure, and pain.
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