Here is a brief tour of the Nervous System, which is
composed of the Central Nervous System (CNS) and
Nervous System (PNS). The CNS is composed of the brain and spinal cord.
The PNS is made up of the nerves that run to and from the body and
organs (sensory and motor fibers) to the CNS.
The sensory nerve fibers
of the PNS carry nerve impulses (information) from the various senses,
including pain, touch, temperature, etc. from throughout the body to
Sensory information from the five senses are carried
by special, heavy duty, cranial nerves and are also part of the PNS.
The eyes are extensions of the brain. They are part of the brain
and are budded off during the early stages of embryonic development.
fibers of the PNS innervate the organs, muscles, endocrine glands,
etc., of the body and cause them to respond to the CNS. There are two
types. The somatic
nerves innervate skeletal muscles. Nerves of the Autonomic Nervous
System innervate organs, the cardiovascular system, viscera, glands,
Neurons, or nerve cells, are the basic building blocks of the nervous
system. Let us first talk a little about the basic structure
of a neuron:
are composed of a cell body, which contains the nucleus and other cell
organelles (not shown). Coming off the cell body are the axon
dendrites. These transmit the nerve impulses in the direction shown.
Nerve impulses come in through the dendrites and travel down the axon.
can be very long as in extending from our brains and down the spinal
cord and down to our little toes. Dendrites are usually much shorter as
indicated. Myelin covers many axons, providing insulation much as the
rubberized (or plastic) insulation covering electrical wires. The
myelin improves the nerve impulse transmission efficiency and speed.
Here is a photomicrograph of actual neurons:
very important part of how nerves work are at the synapses (singular,
synapsis). At the synapsis there is a gap between the neurons that must
be transversed. Neurotransmitters
are biological molecules that ferry the nerve impulse across the gaps
at the synapses.
are all kinds of neurotransmitters. Two primary ones are acetylcholine
and adrenalin (mentioned below). Another important one in terms of mood
(as in depression) and anxiety is serotonin.
are two basic types of neurons we want to mention at this point, motor
neurons and sensory neurons. Motor neurons carry impulses from the
brain to muscles and organs. Sensory neurons carry impulses from
sensory receptors to the brain. Sensory receptors include the five
senses (taste, smell, auditory, touch, sight) and many others.
Nervous System (ANS)
As part of the
PNS, the ANS is composed of two parts, the Sympathetic and
Sympathetic Division mobilizes body systems during emergencies. It
activates the Flight-or Fight response system and secretes adrenalin.
Its activation response is augmented by the release of
and nor-adrenalin from the adrenal glands that sit atop the kidneys.
The Parasympathetic Division deactivates or counters the effects of the
Division and results in relaxation and recuperation (and healing). It
Central Nervous System (CNS)
CNS can be divided into the “Higher” and "Lower"
Brain. Figure 1 shows a side view of the outside or higher
the cerebral cortex.
higher brain centers consists of the Cerebral Cortex. These make up the
right and left cerebral hemispheres. The cerebral cortex is the
“executive suite” of the nervous system, allowing consciousness and
conscious behavior and makes up 40% of brain’s mass.
lobe is very important for analytic and voluntary motor activity,
logic, personality, and perception. It also houses the
emotion-cognition link with the limbic system (discussed below).
pre-frontal lobe, a subdivision of the frontal lobe, is important for
executive functions, which includes organizing complex tasks, decision
making, personality, and social behaviors. This is often the trouble
spot in our troubled teens because of its late development.
"lower" brain centers include everything “underneath” the cerebral
hemispheres. While the anatomy of the internal structure of
brain is very complex, for our purposes we can limit discussion to a
few components shown in Figure 2:
is the major relay station of the brain. It relays nerve impulses from
lower brain centers and body to the cortex. Among its many functions,
the thalamus is involved in memory processing.
is the main visceral (= internal organs) control center for the body.
It is an autonomic control center it functions “automatically”, that
is, without conscious control. The hypothalamus controls body
temperature, food intake, water balance, circadian (sleep-wake)
cycles, and control of endocrine system (via pituitary gland). Its
components also play a major role in emotional responses and behaviors.
It is the heart of Limbic System (below).
Functional Brain Systems
functional brain systems are defined as anatomically diverse systems
with specific functions. This means they are made up of several
different anatomical parts that all work together for a specific
function. They are networks of neurons (nerve fibers) that work
together and span relatively large distances within the brain. They
include the Reticular Activating System and the Limbic System.
Reticular Activating Systems (RAS)
RAS controls arousal of the brain as a whole and determines to what we
pay attention. It acts as a filter, determining to which incoming
information we will pay attention. Here is a primary area that affects ADHD.
The difficulties ADHD individuals have in focusing their attention or
focused may be due to a suboptimally functioning RAS. The RAS also in
involved in controlling the wake-sleep (circadian) cycles along with
hypothalamus. The RAS is housed in the brain stem--the upper part of
the spinal cord just before it goes into the brain.
Limbic System is Our Emotional Brain. It is closely connected to the
smell part of our brain. Hence, the strong association between odors
and emotions. It structures lie in the midbrain. The hypothalamus,
again, lies at the heart of this
system. The amygdala (not shown), for example, plays a critical
role in fear, anger, and the flight-or-fight response.
Limbic System plays a major role in psychosomatic illnesses. It
mediates the intimate relationship between our thoughts and our
feelings. Communication between the cerebral hemispheres and Limbic
explains anatomically why emotions can override logic and, conversely,
why reason can affect emotions.
This system is a key structure
in the evolutionary development from reptiles to mammals. Reptiles have
a greatly reduced limbic system, if you can speak of it at all as a
"system". About all a poor lizard has in way of emotions is your basic
flight-or-fight emotions, fear and anger.
Cerebral Cortex Lateralization (a.k.a. left brain
and right brain)
In our business (mental health) and many of areas of specialization you
will often here people talk about being left brain or right brain. They
are actually referring to the two sides (hemispheres) of the cerebral
The two hemispheres of the cerebral cortex are specialized. More recent
studies with functional MRI's has shown the picture is more complicated
than described below. However, the general description below will do
for our purposes. The situation is given for right handed individuals.
Technically, it is not actually "reversed" for left handed individuals
(about 15% of the population).
The left hemisphere is specialized for speech and linear, logical,
rational thought. It is the dominant hemisphere in language. Restated,
it is our language or verbal hemisphere. It "thinks" in a detail,
sequential, linear manner (sort of 1+1+1=3).
This is the side that most talk
therapy engages. Unfortunately, a lot of the mental health
issues are in the subconscious (or unconscious, I use these
interchangeably). this is the right hemisphere's domain.
The right hemisphere is the non-verbal, intuitive, non-linear part of
the brain. It is better able to deal with the big picture and make
intuitive jumps to solutions or relationships. For it, 1+1 ≠ 2.
Experiential therapy , focus on right hemispheric processes
which are then moved over to the left hemisphere where we can talk
about them. These include, hypnotherapy
psychotherapy, art therapy, music therapy, non-traditional
or complimentary therapies, touch therapy, spiritual healing, and
shamanism. Ancient healing methods focused
on right brain functions.
Comment: Our Left-Brain Society
Western society and education systems
are nearly entirely left-brain directed. They “educate” the left brain.
Only in the arts and humanities is more of our education directed
toward the right brain side of things. What's wrong with this picture?
Wave EEG Patterns
The brain has four basic types of brain waves, alpha, beta, theta, and
These are low amplitude, slow synchronous waves of 8-13 cycles per
(cps). They indicate a calm, relaxed state of wakefulness. These type
of waves are seen during
meditation with experienced meditators. They also play an important
role in the healing process in mental health. We talk about their role
in healing in our "Neruobiology of Healing" section. They are involved
in what is called the Integrative Mode of Consciousness, a special
is also some evidence indicating that when two people are placed in a
room together and one is in a relaxed, alpha wave state, it will
entrain the other persons brain to move into the alpha wave mode too.
Cool, no? Dr. Y uses this approach a lot with his teens.
waves are also rhythmic
but more irregular than alpha and of higher frequency—(14-25 cps).
They predominate when we are awake and mentally alert, as in
trying to solve a problem, carry on a conversation, reading, and many
of our activities during our awake hours. These are the waves of talk
waves are more irregular than either alpha or beta waves. They have a
frequency of 4-7cps. These are slow waves. They occur in children
and adults in early and REM (Rapid Eye Movement=dream) sleep.
occur during Integrative Mode of Consciousness.
These are high amplitude, low frequency (≤ 4 cps) waves that are seen
deep sleep and when the Reticular Activating System is damped as in a
coma or anesthesia.